book On Animal Electricity 1897

DUPLICATE
HX00017353
JiT^
^^*^-
COLUMBIA UNIVERSITY
DEPARTMENT OF PHYSIOLOGY
THE JOHN G. CURTIS LIBRARY
LECTUEES ON PHYSIOLOGY
FIRST SERIES
ON ANIMAL
ELECTRICITY
BY
AUGUSTUS
D.
WALLER,
M.D.,
F.R.S.
Fullerian Professor of Physiology at the Royal Institution of Great Britain
Lecturer on Physiology at St.
Marys
Hospital Medical School,
London
LONGMANS, GREEN, AND
39
CO.
PATERNOSTER ROW, LONDON
NEW YORK AND BOMBAY
1897
'
""'"f'li
DltVI
(
'
(
PREFACE.
ERRATUM.
Description of Fig. 29 (858), for negative after-
p. 65.
effect
with the twelve spoken
the fifth
it
and
sixth,
read negative
The
lectures.
effect.
move
fornicr,
especially
include matter that I should have felt
impossible to consider at length in the face of a non-tech-
audience, hut
nical
to the
I
nevertheless
further study of the subject.
largely
three
that
diluted
lectures
-with
The
regard as essential
latter iv ere of necessity
elementarv explanations,
and included
on the electromotive action of the heart, and
on the action of nitrous oxide, the publication of ivhich
reserved for
In
Britain
as
a
''
second
Physical
an organ
series."
Science
has played a
the
useful
Royal
as
of public instruction
who fashioned
the
is
future
icell
;
destinies
Institution
as
and
of
a
of
Great
brilliant
part
the great physicists,
the
Institution,
did
Preface.
iv.
not neglect
is
to
domain
tJie
which
cnltivate that portion of pJivsical science
the
of
pJivsiologist
—
tJie
pliysics
living
of
matter.
Davy, by
pointed ont
Faraday
way towards
took part
Animal
electric
tJie
in
It
of Chemistry
his physiological
indeed
is
rattier
the establishment of Ancesthesia.
foundation of onr knowledge of
the
by
Electricity
eel.
stndv of nitrons oxide,
close physiological
his
investigation
of the
through
its
Fnllerian
Professors
than through
its
Fnllerian
Professors
of Pliysiology, that the
Royal Institntion has furthered onr
knowledge of living matter.
No
clearer proof conld
dependence of any
rather than upon
ship
of
its
branch
be
ivell
upon
of Science
of the absolute
its
laboratories
The Fnllerian professor-
lecture-theatre.
Chemistry has
offered
been fruitful,
not only
in
its
own
department, but also in the allied department of Physiology.
The
Fnllerian
paratively
sterile,
Botli chairs
but
tlie
Physiology
of
within
even
its
own
has
been
com-
nominal province.
have been held by men of the highest distinction;
former has
latter— so
possess
professorship
far from
rested
resting
upon
upon
a
laboratory,
a
even one small room in which
wliile
the
laboratory — does
not
to
keep itself alive.
A. D.
Weslon Lodge, 16, Gvovc
Aumist,
1897.
End Ruad, N.W.
WALLER.
CONTENTS.
LECTURE
I.
PAGES
Currents of animal electricity are produced by animal
which injured or active protoplasm is electro-positive (" zincative "), resting
protoplasm electro-negative (" zincable ").
voltaic couples, in
The
utilisation of a
nerve as a test-object representative
of living matter.
— Current of a voltaic couple. Current of
— negative variation. Current
of injury of nerve —
negative variation.
Paral-
Experiments.
injury of muscle
its
its
lelism
between mechanical and
electrical
of ether
effects.
Action
Electrical effects of non-electrical stimuli.
and of chloroform upon isolated nerve
LECTURE
...
1-29
IL
method. Illustration of Ohm^'s law.
Dead-beat and oscillating magnet. Alcohol, soda
water, tobacco smoke.
Carbonic acid. The funcIntegration and disintegration.
tion of respiration.
Description of
Action of carbonic acid in further detail
LECTURE
...
...
30-54
III.
On
the production of COo by tetanised nerve.
Hypothesis and experiment. Three stages. Comparison between the effects of CO. and of tetanisation.
Direction of further inquiry.
case effect.
l^°stscript
Summation.
Significance of the stair" Bahnung."
33.75
Contents.
vi.
LECTURE
IV.
PAGES
Polar
law.
Pfliiger's
effects.
Illustrated
by experi-
ments on Man.
Electrolytic dissociation.
Electrolytic counter-current.
Internal polarisation.
Polarisable core-models.
Extra-polar currents in core-
models.
Extra-polar currents in frog's nerve and
nerve
...
...
...
...
in
mammalian
...
...
...
76-100
LECTURE V.
ELECTROTONUS.
" An." and " Kat."
form.
Influence
Physiological
ether and
of
and physical
electro-mobility of living matter.
polarising
and
Strength.
Distance.
extra-polar
currents
Von
Fleischl's
mammalian nerve
...
ELECTROTONUS
Influence of acids and alkalies.
acid and of tetanisation.
in
nerve.
deflection.
Extra-polar
...
...
LECTURE
The
Relation between
Action currents are counter-currents.
effects in
chloro-
eff"ects.
...
101-123
VI.
(continued).
Influence of carbonic
Influence of variations
of temperature.
The
action-currents of
electrotonic
increment
...
nerve.
Bernstein's
Hermann's
polarisation
polarised
decrement.
...
...
...
...
...
124-144
ILLUSTRATIONS.
LECTURE
Fig.
I.
„
2.
I.
--------------------
— A lump of protoplasm as a voltaic couple
—A simple voltaic couple
— Zinc electro-positive
is
„
3.
„
4.-
— Muscle currents
-
,,
5.
„
6.
— Nerve currents
— Simultaneous record
„
7-
— Simultaneous
„
8.
„
9.
-
-
-
-
mechanical and
of the
responses of muscle
-
-
-
-
-
-
-
-
-
-
-
-
-
---------------------------------
LECTURE
II.
„
12.
„
13.
„
14.
„
15.
„
16.
„
17.
„
18.— Excitant
-
-
-
-
effect
effect of
-
-
-
-
39
-
-
32^?.
„
33.
„
34.
47
60
-
61
-
in first,
-
-
-
-
-
-
-
----------
second and third stages
— The staircase effect of the heart
— The staircase effect in nerve
— Effect of tetanisation on " unfed nerve
— Effect of tetanisation on " fed nerve
„
43
47
-------------------------"
nerve
43
in.
32.
„
43
52
,,
„
33
-
„
,,
20.
23
38
expired air
LECTURE
„
18
23
-
— Effect of COo on carbonised nerve
— Hypothesis
21. — Verification
22. — A typical " dead-beat
series
23. — Three stages
24 to 31. — Influence of carbon dioxide and of tetanisation upon
„
13
-
-----
effect
19.
10
IL
— Plan of apparatus
—An application of Ohm's law. Compensation.
— Dead-beat and ordinary galvanometers
— Effect of soda water on nerve
— Effect of alcohol on nerve
— Effect of tobacco smoke on nerve
of carbon dioxide
— Excitant
—Anaesthetic
of carbon dioxide
10.
5
8
record of the electrical response of nerve
and of the mechanical response of muscle
„
2
4
electrical
— Effect of ether on nerve
— Effect of chloroform on nerve
„
HAGE
"
"
-
-
56
58
-g
64-5
68
68
-
-
-
-
74
-
-
-
-
74
viii.
lUiisfnifions.
LECTURE
nerve
„
36.
„
37.
IV.
----------
—Anodic and
t IG. 35.^
— Excitability and zincability under the Anode and Kathode
— A polarisation
cell
-
-
-
-
38.
-
-
-
39.
-
-
-
-
-
-
-
„
— Internal polarisation of the human subject
—Anodic extra-polar currents of a core-model
— Kathodic extra-polar currents of a core-model
41. — Electrolysis at four surfaces
42. — Extra-polar currents of frog's nerve
„
43.
„
„
J,
„
------
40.
-
-
-
LECTURE
„
47.
„
„
„
44.
^Schema
„
„
„
-
„
„
„
„
„
„
„
— Influence of CO2 on K.
52. — Influence of CO2 on A.
53. — Influence of CO, on A.
51.
alkali
56.
157.
58.
59.
„
62.
„
63.
„
64.
„
65.
„
66.
„
67.
-
96
-
97
.
-
-
-
-
-
-
-
-
-
-
-
-
-
102
109
115
120
VI.
-
125
125
-
61.
93
95
105
-
-
-
-
-
128
-
-
-
128
.
-
-
.
129
-
-
-
-
129
-
-
-
-
130
-
-
rise
for
-
-
for
-
-
125
-
-
55.
90
92
105
— Influence of
(KOH) on A. and K.
— Influence of acid (propionic) on A. and K.
— Influence of ammonia on A. and K.
— Influence of CO2 on A. and K.
— Influence of tetanisation on A. and K.
— Influence of CO2 on A.
60. — Influence of tetanisation on A.
— Influence of CO2 on A.
— Influence of tetanisation on A.
— Influence of
of temperature on A. and K.
— Plan of connections electrotonic decrements
— Anelectrotonus and Katelectrotonus
— Plan of connections polarisation increments
— Nerve currents summarised
54.
.
-
-
of electrolysis in a medullated nerve fibre
LECTURE
„
-
84
86
----..
-----in
------------------------------------
— An. and Kat. of frog's nerve
49. — Von Fleischl's deflection
50. — An. and Kat. of mammalian nerve
48.
-
82
V.
„
„
-
— Extra-polar currents of mammalian nerve
—Anelectrotonus and Katelectrotonus
45. — Influence of ether upon An.
46. — Influence of chloroform upon An.
„
PAGE.
Kathodic alterations of excitability of human
-
-
129
i-^o
131
-
-
131
-
-
'34
-
-
136
-
-
^37
-
-
138
-
-
143
ANIMAL ELECTRICITY.
"Wonderful as are the laws and phenomena of
when made evident to us in inorganic
electricity
or dead matter, their interest can bear scarcely
any comparison with that which attaches to the
same force when connected with the nervous system and with life." Faraday. '' Expei-imental
Researches in
Electricity.^''
LECTURE
Fifteenth series, 1844.
L
Currents of animal electricity are produced by animal voltaic
couples, in which injured or active protoplasm
is
electro-
positive (" zincative "), resting protoplasm electro-negative
(" zincable ").
The
utilisation of a
nerve as a test-object representative of living
matter.
— Current of a voltaic couple. Current of injury of
— negative variation. Current of injury of nerve
Experiments.
muscle
—
and
its
negative variation.
its
electrical
stimuli.
effects.
Parallelism between
Electrical
effects
mechanical
of non-electrical
Action of ether and of chloroform upon isolated
nerve.
The
master-key to
many
otherwise most intricate
and complex problems of animal
simple idea.
^
Active matter
is
electricity is a
very
electropositive^ to in-
This nomenclature, which is the opposite to the convenperhaps be found justified by the context
tional denotation, will
LECTURE
ANIMAL ELECTRICITY.
2
active matter
more
;
active matter
to less active matter
up
stirred
to
;
greater
matter that
activity
action
is
lowered
action
is
normal.
is
is
electropositive
by any means
rendered
matter,
towards undisturbed
positive
is
is
I.
electro-
matter whose
electronegative to matter
whose
Picture to yourself a uniform mass or strand of
protoplasm, that
Fig.
Any
A.
I.
is
to say of living matter, inactive at
—A lump of protoplasm as a
injured,
i.e.,
voltaic couple.
chemically active spot
Current in the lump
of these lectures.
is
from
B
B
is
zincative to
any uninjured spot
to A, in the galvanometer from
A
to B.
In the phraseology generally employed by
is said to be " negative," and the
physiologists the active spot
But more
term "negativity of action" is derived from this.
should
and
is
positive,
we
the
active
spot
correctly speaking
properly say " positivity of action." But to reverse these and
other derived terms in common use would lead to hopeless confusion, which I desire to escape by employing the terms zincative,
Moreover we shall soon experience the want of a
zincativity.
word to denote that a resting spot, capable of activity, is capable
of becoming positive, or has a capability for becoming positive
this will be met by the words zincable, zincability, which are by
no means to be taken as synonymous with the terms excitable,
;
all
ANIMAL ELECTRICITY.
LECTURE
what comes
same
points, or
active
at
all
to the
Any two
points.
3
I.
thing, equally-
being
points
ex
hypothesi equally active, are equally electromotive
"isoelectric,"
— and
if
connected by wires to a galvan-
But
ometer, exhibit no current.
stir
up B by pinching
or pricking or by a touch of a hot wire, and you
once obtain a current through the galvan-
at
will
ometer that indicates the presence of current
rest of the circuit as
shown by the arrows.
mass of protoplasm which
active
throughout,
A, there
but
current from
is
ometer the current
is
B
from
These two unequally
active
to
A
In the
no longer uniformly
is
more
in the
A.
at
B
than at
In the galvan-
to B.
active
B and
regions
A
form a weak voltaic couple, of which B, the more
active spot,
(we
where more chemical action
shall further
is
going on
on inquire into the possible character
of such chemical action),
is
the generating or electro-
A
spot of tissue under the influence of the anode
and more zincable. I have not been willing to
use the less inelegant words electromotive and electromobile in
place of zincative, zincable, for fear of an ambiguity in the term
electromobile which has seriously impaired the precision of the
term excitable. A tissue may be more excitable (erregbar) inasmuch as it may be aroused to action by a weaker stimulus, or
more excitable (leistungsfahig) inasmuch as greater action is
aroused by a given stimulus. A more zincable spot, as the name
excitability.
is less
excitable
suggests,
is
capable of greater electropositive action than a less
zincable spot.
ANIMAL ELECTRICITY.
4
positive plate,
and A, the
chemical action
is
LECTURE
I.
less active spot,
where
less
going on, the collecting or electro-
negative plate.
Let
me
try to fix this point in
two elementary experiments,
direction of current
by a
and copper), the second
the
your memory by
first
to specify the
typical voltaic
to identify with
couple (zinc
such a current
the current of animal electricity that passes from
more
active to less active tissue.
COPPER
ZINC
—A simple voltaic
Fig.
2.
The
surface
couple.
between zinc and fluid is the principal seat of chemical action.
Through the galvanCurrent in the cell is from zinc through fluid to copper.
ometer it is from copper to zinc.
Pj^eliminary Experiment.
slip
—A
slip
of zinc and a
of copper dipping into a glass of salt solution
and connected with a o-alvanometer
will
exhibit the
character and direction of action of a representative
voltaic couple.
The
current will indeed be so large
that with this delicate instrument arranged as
is.
for
the far smaller currents generated in living nerve,
we
must
" shunt "
it, i.e.,
only
let
pass through the galvanometer.
it
a small fraction of
it
ANIMAL ELECTRICITY.
The
direction of deflection
copper.
forget,
is
I.
5
as you see such as
from zinc
to
Whatever you may choose to remember
bear in mind that zinc is the active plate,
or
indicate current in
to
LECTURE
the voltaic
which chemical change takes
place,
cell
and electromotive
Later on when
pressure takes origin.
at
we come
to
we
deal with the electrical response of living nerve,
shall find
it
of the utmost convenience to
make
use
of language based upon this fundamental notion, to
speak of living nerve as being more or
less zincative
or zincable, as having- oreater or smaller zincativitv
and
zincability.
Second Preliminmy Experiment.
simplify matters
Fig.
3.
further
— Let
omitting the
;
— A bit of zinc wire held in the
right
us in fact
copper plate
hand and touching one terminal
of a galvanometer circuit (while the other hand rests on the other terminal) gives
current in the body from right to
The
current
and
is
is
left,
in the
directed from zinc to fluid.
(If the
by dipping the
i.e.,
left to right.
galvanometer wire, instead of ending
a metal terminal R, dips into a glass vessel of
—
galvanometer from
aroused at the contact between the zinc and the slightly moist skin,
zinc into the
same
salt solution,
solution, current
anti-clockwise instead of clockwise
and
circuit is
at
completed
would run the other way round
—being as before from zinc
to fluid.)
ANIMAL ELECTRICITY.
and substituting
in the circuit
and a
own body
for the
by laying one hand upon one
vessel of salt water,
terminal,
our
zinc rod held in the other
hand upon
the other terminal.
As
before,
you see that the current
from the zinc
is
through the body, and
to the zinc through the galvan-
ometer,
electro-positive.
You
the zinc
i.e.,
is
find in this simple observation not only
will
a stepping-stone towards the proper understanding
of an animal current, but a ready practical device for
ascertaining in a complicated circuit
any part of the
current at
what
circuit is indicated
given deflection of the galvanometer.
your body into
circuit
direction of
If
you put
by taking one end of a wire
one hand L, and touch the other end with a
zinc,
in
you
will
zinc,
If that deflection
i.e.,
from
of the
is
R
deflection
the
in
of
is
activity
L
in the
direction as
you know that
the latter was produced by activity on
reversed,
to
same
that of the deflection under question,
if
bit
get the deflection indicative of current
your body from the
figure.
by a
the
R
side
;
has been on
the opposite side.
Our
first
representative experiment
is
of the imaginary case that
we took
had best be shown
at least twice,
to
you
representative excitable, that
is
a realisation
as our type,
and
on the two
to say, living tissues
on a muscle namely, and on a nerve.
We
ment
is
will
begin with muscle, with which the experi-
easier to
make and
easier to understand.
ANIMAL ELECTRICITY.
LECTURE
I.
First Representative Experiment (on
This isolated muscle
dead frog
—
—
of a
connected with the galvanometer by
is
two electrodes touching
it
As
(fig. 4).
stands,
it
T
two points
at
tendinous end or transverse section, and
surface
Muscle),
the living muscle
is
it
7
in
is
it
—
it
has been
all
certainty
not absolutely uninjured and normal, therefore in
homogeneous and
certainty not
for life
if
is
essentially slow death
you prefer
it
more rapidly
If so
—and
may make
matter
—
L,
zincative
T
its
thick part L.
complete
it
to
stirred
less
active
first
fix
injury
matter,
was
in
its
—
giving
half of the experiment.
its
the
meaning
same
to
principle,
you.
place in the body,
The
when
has been carefully
dissected out and protected from drying so that
is
still
alive.
up by weak
contracts
—
Its far
end from the muscle
faradisation,
telling
is
electricity.
half, illustrating
and
up by
nerve throus^h which this muscle was controlled
it
be
will
on muscle that active
instance
complementary
—T
I
illustrating
This has been the
will
than at
have current as shewn
thereby a current of animal
Its
dying (or
it is
shall
relation
in
dying
purpose of making quite sure,
and we
this
in
—and
it is
so by a touch of a hot wire
it
diagram,
this
to say
any case chemically changing,
end
at its thin
for the
zincative to
by
living) in
all
electrically indifferent
It is living, that is
at all points.
its
longitudinal
its
and though
prepared as gently as possible,
and L
is
it
stirred
and you see that the muscle
you by
its
contraction that
it
and
ANIMAL ELECTRICITY.
e5
nerve are
its
still
alive
—and
LECTURE
at the
I.
same time you see
way by the current
other way [i.e., under-
that the spot of light deflected one
of injury from
T
to L,
moves the
goes a negative variation) when the muscle contracts.
This negative movement of the spot means that the
chemico-physical
FiG.
4.
change taking place
the
in
con-
— Muscle currents.
The "current
of injury"
action " (negative variation
from
is
T
to
L
The "current
in the muscle.
of the current of injury)
is
from
L
to
T
of
in the
muscle.
tracting muscle
is
greater at
L
than at T, or that
L
has become zincative to T.
A little reflection
fact falls
under our key
a current of injury
L T
;
by exciting
and
clue to
was active and
of further activity,
T
will
L
its
We
principle.
this
started with
a difference between
T
and
zincative, therefore less capable
i.e.,
less zincable
we stirred up
we obtained a
nerve,
included,
soon convince you that
than L.
When
the whole muscle,
greater augmenta-
ANIMAL ELECTRICITY.
LECTURE
I.
9
tion of activity at L, the resting part, than at T, the
The
already active part.
at
T
was due
current of injury generated
T
between
to a difference
and L,
its
diminution of that difference.
L was due to a
And there must be
a difference before there
be a
negative
generated at
variation
can
of
diminution
there must be a current of injury for you
difference;
to get a negative variation of
If the
it.
muscle had
been chemically homogeneous throughout, whether
rest or in action, with therefore
at
T L
any two points
equally zincable or equally zincative, there could have
been no (or
L when
little)
T
between
difference aroused
and
both are equally (or nearly equally) altered.
Second Representative Experiment (on Nerve).
In the
first
experiment (on muscle) the nerve was
used merely as an instrument to
and the muscle spoke
movement
of
its
change revealed
in
two ways
substance,
in the
stir
up the muscle,
— by
an actual
by a chemico-electrical
galvanometer.
In this second experiment (on nerve) the nerve
is
to
be used by
itself,
of expression, which
points
T
and
L
is
cut off from
its
natural organ
muscle, and connected by the
with a galvanometer that
will
serve
as an artificial organ of expression.
We
shall
begin by testing the nerve for current
of injury, expecting to find
in
it
directed in the nerve as
the muscle from disturbed Transverse section to
undisturbed Lono-itudinal surface.
Now,
let
And
us arouse the whole nerve
so
it is.
—and
for the
ANIMAL ELECTRICITY.
lO
LECTURE
purpose of a distinct demonstration,
to
let
do so otherwise than by
may
I
hardly hope
electrical stimulation
—and
us watch for a neofative variation of our current
The
of injury.
mistakable
it
I.
to
two
(and while
;
5.
the
tests,
explained later
Fig.
variation
— the
is
we
not large, but
are about
it
it
of which
significance
will
and the
test of direction
un-
submit
will
I
is
be
test of
—Nerve currents.
The "current
of injury"
is
from
T
to
L
in the
The "current
nerve.
action" (negative variation of the current of injury)
is
from
L
to
T
of
n the
nerve.
distance.
I
have now reversed the direction of the
electrical stimulation,
and the variation has remained
negative and of unaltered magnitude.
I
have now
brought the exciting electrodes much nearer to the
leading out electrodes, from a distance of about 3 cm.
to
one of about
i
cm, and
repeat the test with both
I
directions of stimulating current
variation remains negative
tude.
effect
We
;
still
the
negative
and of unaltered magni-
are thereby entitled to conclude that the
was a "true negative
variation,"
and not due
ANIMAL ELECTRICITY.
to current escape
LECTURE
II
I.
nor to du Bois-Reymond's electro-
tonic current.)
The
value
you
which
at
be disposed to
will
estimate the electrical signs of physiological activity
be greatly enhanced by the closer consideration
will
of the
in
Here you have
experiment (on muscle).
first
the mechanical effects of muscular contraction, an
measure
obvious
of
physiological
its
muscle shortens much or
siological activity
asks
trical
A
or
himself whether with
mechanical effect there
—the
its
phy-
and one naturally
little,
greater or smaller
this
a greater or smaller elec-
is
effect.
very simple variation of the experiment
answer us
the
in
beyond
all
will
and the records of
affirmative,
more prolonged observations
ative
according as
little
much
is
activity
confirm that affirm-
will
doubt.
Let us go back to the experiment on muscle, and
make
much
the muscle contract
or
watching by
little,
the oralvanometer to see whether the size of the electrical
effect corresponds.
things at once, so
It is
place
in
show you the end of a
difficult
acted
muscle and marking against a
runs
indicator,
cator.
spot
the lantern
past
;
and the galvanometer
If
while
now you
the
strongly, you
will
muscle
is
watch
itself
I
upon by the
smoked
the lever
watch two
muscle
of the
lever
to
plate
that
the contraction
is
the current indi-
is
the
stimulated
will see that the spot
galvanometer
more or
less
makes a greater
ANIMAL ELECTRICITY.
12
or
smaller
you
and
niovement,
see that
will
LECTURE
turning
I.
muscle
the
to
muscle has contracted more
the
or less strongly.
This
as
a very simple but very important
is
a link
in
arorument
the
that
muscular action involve more and
change,
current
a
and
larger
smaller
More and
you get
quiescent muscle
of
the
arousing
the
negative
a
chemical
less
diminution
And whereas by
of injury.
chano^es
electrical
are a measure of physiological activity.
less
fact,
of
variation
the current of injury, you would get a positive variation of the
same by "quelling" an
To
assured of this correspondence between
be
and
mechanical
the
cause
— chemical
record,
tions
of
fully
electrical
activity,
where the white
and the black
electrical
effects
muscle.
active
effects
of
one
this
pray look at this double
line gives series of contrac-
line
the
one
of
corresponding
series
and the same muscle
(fig. 6).
Each of
the two series exhibits a declining effect
the expression of muscular fatigue
decline
is
nearly the
the same, however
at all critically,
;
tell
although the point
I
is
in
more
evident divergences
precisely the
same
story
not one upon which
may observe
accurate.
Not
both cases.
that of the
the mechanical and the galvanometric
the
the rate of
quite
you examine the twin record
if
there are
two records do not
dwell now,
same
— and
It
gives
the
;
and
;
we need
two versions
—the
a declining
latter
is
series
oi
ANIMAL ELECTRICITY
LECTURE
I,
13
U^U^IumaaMi'
EiG. 6 (2462).
— Simultaneous record of the mechanical and electrical responses
of a gastrocnemius muscle (frog), excited by tetanising currents for 7^ seconds (60
to 70 interruptions per sec.) at intervals of I minute.
The upper
The lower
on black) gives the series of lifts of a weight of 10 grms.
on white) gives the corresponding series of electrical
effects ; the large deflections at beginning and end of the series are standard
deflections made by yi^ volt.
Dead-beat galvanometer (shunted).
In the first and second pairs of responses the strengths of stimulation were 4
and 5 units ; in the third and subsequent pairs the stimulation was at 10 units.
line (white
line (black
ANIMAL ELECTRICITY.
14
which the tops
line
and
;
method
made
tension against that
its
you would have witnessed a declining
little)
much more like the
But we shall come back to
of tension
series
to record
method by which
spring which allows the muscle to shorten
stiff
but very
a curve convex towards the base
lie in
(the so-called "isometric"
is
I.
had adopted a rather better mechanical
if I
the muscle
of a
LECTURE
vanometer
series.
point in dealing with the subject of fatigue
present
I
am
only concerned
opinion that the galvanometer
modifications
physiological
convince you
that
it
this
for the
;
establish in your
to
a good indicator of
is
later
;
in
is
and most accurate indicator
To watch
gal-
effects
hope
shall
I
respect
this
the
to
best
at our disposal.
the alterations of physiological activity
taking place in fatigue or under other influences
matters
regards
as
little
the
muscle
itself
it
whether
you make use of a lever or of a galvanometer as
Each record
your indicator.
is
almost a replica of
the other, and contrary to your expectation perhaps,
method by galvanometer, once the
the less obvious
preliminary difficulties have been overcome,
to
work,
as
well
as
far
more
delicate
is
easier
and more
accurate than the mechanical method.
More than one very
from
ment
this
simple observation, but
upon
electrical
muscle,
significant
one
effect
at
is
an
this
exact
and may therefore
measure of action
in
stage
nerve.
I
—
inference
shall only
to
measure
be
arises
wit
of
appealed
comthe
that
action
in
as
a
to
— LECTURE
ANIMAL ELECTRICITY.
There
I.
I
5
however, one preliminary objection to
is,
the unlimited admission of this conclusion that must
be taken at once.
We
arouse
action
"stimulation," and our
we
convenience
nerve
artificial
stimuli
mechanical,
chemical,
trical,
the
in
most
artificial
may
be elec-
As
&c.
a
this
apparatus
of
stage
An
?
aroused
effects
with
certainly be
and
;
while
that
been used,
has
even when produced by
electrical
is
shall
I
electrical
may sometimes
be coarse
when
they can
yet
produced by non-electrical
nomena proper
our
to
general most pronounced
in
stimulation
electrical
saying
nerve
in
and are
fallacies,
due
means by which the answer
the
myself
be sure
exhaustive examination at
obtained would lead us too far afield
content
electrical
May we
coil.
that the animal electric effects are not
electrical
matter of
employ
frequently
stimulation from an induction
by
and
stimuli,
stimuli,
phe-
are
to the living state of nerve.
Reasons
for admitting this will be offered presently
by means
of anaesthetics, as soon as
the
bearing
of
in
which an
L and
from
usual
as
T
T,
to
giving as
L
(in
nerve by pinching
contracts
with
the
it,
the
The muscle
the
muscle).
current
I
now
non-electrically
and the current of injury
time diminished.
first
galvanometer
usual
i.e.,
our
experi-
electrical effect results
from non-electrical excitation.
nected
clearly appreciated
of
variation
this
ment (on muscle),
we have
is
;
at
con-
is
by points
of
injury
excite
the
the muscle
the
same
I
ANIMAL ELECTRICITY.
6
That has been
excitation,
electrical
an
LECTURE
electrical
and
I.
might with a
I
non-
a
of
effect
little
care
and a rather more sensitive galvanometer demonstrate a similar effect
I
might proceed a step
electrical
electrical
fluous
show
do
to
electrical
we
it
was
therefore
by the
not determined
stimulus.
Later,
retina,
we
shall
convinced of
when we
manifested
effects
trical
see
stimulation
few
a
use
of
you should
it,
rare
and
realise
nature of the effect
electrical
shall
nature
be
to
of
examine the
by the heart and
cause
is
be so nicely
in
make
that
essential
simply to
not indispensable
except
at the outset that the electrical
is
is
applied, can
systematically
shall
is
Electrical
effect.
and graduated, that
cases
which
stimulus
however so conveniently
timed
would be super-
this
present purpose,
that an electrical
an
to
my
impulses aroused by
whether these be or be not of
But
origin.
to
finally,
and show that an
further,
as the
as well
stimuli,
artificial
;
accompanies a natural discharge of
effect
nerve-impulses,
all
on the isolated nerve
elec-
by the
more
still
the
fully
this.
In recollection of the fact that as regards muscle
the mechanical and electrical response to stimulation
run a nearly parallel course, and utilising the fact
ascertained
first
by du Bols-Reymond that an im-
pulse aroused at any part
in
both directions
may
establish
a
from
of a
the
nerve
is
stimulated
comparison between
conducted
point,
the
we
changes
ANIMAL ELECTRICITY.
in
I
I_.
7
a nerve and those in the attached muscle, stimu-
lating the
nerve
chanical
the
contraction,
of the nerve
done
the middle of
in
of
indicator
as
its
of
state
carrying a small
which
of
fig.
mestate
the
is
7
attached
to
a lever
paper flag that threw
its
shadow
upon a photographic
slit
its
This has been
electrical response.
The muscle has been
through a
muscle
the
using
course,
its
and as indicator of the
experiment
the
in
record.
plate,
which
at
same time received the impression of a galvano-
the
metric
spot
of
light
changes
electrical
is
LECTURE
,
in
moving
the
nerve
stimulated once a minute
of
the
nerve
to
the
The nerve
itself.
the muscle at one end
;
the
contracts,
obedience
in
galvanometer
at
the
other end of the nerve exhibits a nerative variation.
The
pointed
shadows of the
moved by
flag
the
muscle, give on the developed plate a record of the
behaviour of the muscle
give
spot
Now
a
;
the excursions of the bright
behaviour of the nerve.
record of the
By
the obvious points are these.
excitation
of one and the same nerve there has been a declining
muscular contractions and a uniform series
series of
negative
of
muscle, to
exhibits
all
variations
appearance,^
As
the
is
no sign of fatigue.
that muscle does
^
of
will
not
nerve-current.
fatigued, while the nerve
It
thus
is
faithfully express
be shown in a future lecture,
terminal (end-plate) than the muscle that
it
is
has nothing to do with the present argument.
2
The
is
very clear
the state of
more the nerve-
fatigued
;
but this
ANIMAL ELECTRICITY.
15
the
nerve
itself,
but
only
LECTURE
that
of
I.
the
combined
organ formed of the nerve, the nerve-terminal and the
muscle.
It is
equally clear that to follow the changes
taking place in the nerve, the galvanometer
able
the
to
muscle.
And,
finally,
if
is
prefer-
once we are
'
•
'
PS
/
kyjkiyjiik^kwyiiijikLLLi,
ANIMAL ELECTRICITY.
tions, effected or
and physical
But
LECTURE
not effected, by
do
interference.
very regularity of response has a suspi-
this
to
is
and the
to
make
The
employ
sure whether or no
step to take
first
vapours.
1
kinds of chemical
all
The
ciously non-physiological appearance.
to
I.
best
for this
Experiment
it is
to test
is
it
first
thing
physiological,
by
anaesthetic
and most expeditious anaesthetic
purpose
— The
is
ether (diethyl oxide).
nerve
resting
upon two pairs
of unpolarisable electrodes, one pair for the exciting
the other servino- to lead off the current of
current,
injury
and
shown
{as
chamber
negative variation to the galvanometer
its
in
figs.
5
which
into
can be blown.
and
is
10),
enclosed in a glass
air saturated
The
with ether vapour
negative variation having been
provoked once or twice by completing the
circuit,
and
and having been found
sufficiently regular, ether
nerve chamber.
at intervals
is
The
exciting-
to be sufficiently large
vapour
is
blown
negative variation
is
into the
tested for
during the next two or three minutes
seen to diminish and to disappear.
of the negative variation
by ether
is
;
it
This abolition
not permanent
;
at
the end of five or ten minutes the negative variation
reappears and gradually increases up
to,
and
it
may
be,
beyond the normal.
This experiment
(fig.
8),
which
represents
the
regular and unfailing consequence of the etherisation
of a nerve,
proves that the electrical effect we are
dealing with
is
a physiological
phenomenon.
ANIMAL ELECTRICITY.
'20
The
LECTURE
thought that suggests
first
I.
when one
itself
has seen by what a surprisingly regular series
electrical
nerve
the
effects
interrogated at regular
intervals,
satisfied oneself further that
physiological,
is
that
responds
we
by which
excellent
test
chemical
reagents upon
of
regularly
if
and when one has
such electrical response
is
are in possession of a most
recognise
to
the
of
action
properties
the physiological
of nerve.
For the
There
is
test is applied to
not, as
nerve and to nerve only.
when muscular
contraction
used as
is
the indicator, any question as to the share borne by
The
muscle or by motor end plate.
isolation of the object of observation
does not move.
The
excitation
its
excitability.
does not exhaust
but by no means
slight,
is
experimental
complete.
by which
It
is
it
It
tested
is
a subsidiary,
advantage, that the photo-
graphic record of each and every observation can be
and preserved
easily taken,
for future reference,
be as authoritative a century hence as
The nerve has
recorded
own
its
during any treatment to which you
to submit
that
it
;
It
cannot give a
may happen
answer
A
that
it
may
its
fail
to
of answers
series
may have chosen
answer
;
give some
to a spurious question, or that
moment
'which
is
false
correctly interpret
to-day.
is
it
and
the worst
spurious
we may
the
for the
language
in
answers are returned.
good instance
to take in illustration will
compare the action of
different anaesthetics,
and
be to
I
will
ANIMAL ELECTRICITY.
at
2
I.
1
once set ooina- a chloroform observation on nerve
manner now
the
in
time
allow
cogent
than
chloroform
that
ether,
come a matter
what
I
recovery
that
significance,
of urgent
have
shall
fact
more
toxic
be
final,
My
a point of great
this
is
may
at
any moment be-
the
to
;
and
in
be impossible not
will
practical appli-
experiments were not,
marily addressed
to
any reasonable
within
it
subject,
powerfully
make statements having immediate
cations.
the
in
personal anxiety
to say
to
sufficiently
apt
is
order
in
be
to
effect
full
Obviously
lapse of time.
practical
far
is
its
by
you,
to
one main
regards
followed
not
familiar
observation
the
for
as
that
viz.,
to
LECTURE
practical
however,
issue
;
pri-
they were
instituted solely for the purpose of testing the value
of
nerve towards
further
its
object.
And
infringe
upon medical matters
after
medical audience,
I
in
shall prefer
the inference as
late
anxious
all,
it
presents
as
I
a
as
utilisation
am
test-
not
to
presence of a nonto
explicitly formu-
itself
to
my
mind,
thinking on the non-medical lines of a purely scienstudent,
tific
rather than
and popular inference
to
to
leave
be drawn
and cautiously than might seem
This
of the
first
January
first
the jubilee year
is
trial
19,
to
less
guardedly
be desirable.
— the jubilee day
in fact
of chloroform as an anaesthetic.
1847, Sir
operation
a perhaps hasty
James Simpson performed
under chloroform
anaesthesia.
On
his
The
manifestly beneficent effects of this powerful anaesthetic
ANIMAL ELECTRICITY.
22
led to
its
widespread preference over
subsequent
so
rivals,
synonymous with
Lord Lister
that in
head
—put
all
other anaesthetic
Nevertheless,
—potent because they are toxic
most potent drugs — chloroform, while
drugs
like all potent
perhaps above
conferring quickly and effectually the great
unconsciousness, exacts heavy
if
are other,
toll.
Not
boon of
too heavy,
chloroform were the only anaesthetic in the
but far too heavy
field,
least,
and many surgeons
agents aside in favour of chloroform.
perhaps,
and
prior
all
has almost become
"
''anaesthetist,"
at their
I.
country at
this
" chloroformist
designation
the
LECTURE
if
less
when we
consider that there
potent anaesthetics to hand, amply
adequate to the needs of nine-tenths of the cases for
which chloroform has been used with
It
fatal results.^
has been said that experimental physiology has
afforded no gruidance in the use of anaesthetics
clinical
experience
is
our only guide.
I
demur
— that
to this
statement, and shall at once exhibit to you a contrast
experiment representing, as
tive efficacy of these
^
in
a nutshell, the compara-
two principal re-agents.
Dr. Lauder-Brunton, although pleading emphatically
in favour
of chloroform as against ether, expresses himself as follows in his
Text-Book
"
The
of Pharmacology (3rd Ed., 1893, P- 801)
operations in which death during chloroform chiefly
:
" occurs are short and comparatively slight, though painful, such
" as extraction of teeth, and evulsion of the toe-nail operations
—
"in which the introduction
of deep chloroform anaesthesia
might
" be regarded as superfluous, and involving a waste of time."
ANIMAL ELECTRICITY.
Ether.
Before.
8 (576).— Effect
Fig.
LECTURE
of
responses of isolated nerve.
23
I.
After.
ether
The
(diethyl
oxide,
Et^O) upon
the electrical
electrical response is abolished for
about five
then gradually recovers, and becomes somewhat larger than it was
before etherisation.
The excitations and responses of the nerve are at intervals
of one minute.
minutes
;
it
Before.
Chloroform.
After.
—
Fig.
Effect of chloroform (Trichlormethane, CHCI3) upon the
9 (552).
electrical responses of isolated nerve.
The electrical response is definitively
abolished
;
there
is
no recovery during the period of observation.
LECTURE
ANIMAL ELECTRICITY.
24
The
action of ether you have just witnessed
was quite
effect
I.
consummated
typical
—an
about
in
;
the
aboHtion of excitabihty
and
minutes,
three
lasting
another five minutes.
But how about chloroform
vapour
?
on testing
;
it
its
Those
"
was promptly
its
excitability
strikino-
—you have
slight differ-
contrast.
There are
considerations to
viously a question of this
single experiment.
in
How
each case a
moment
be weighed
is
chloroform.
cent, of ether
And
to
ob-
The nerve
about quantity?
maximum
;
not settled by a
dose,
i.e.,
for a period
of one minute, air saturated with the drug,
about 50 per
abol-
— no
are the facts in the rough
accessory
has had
strong
"death by chloroform."
ence of decree, but a
many
in
now, you see that nothing happens
the nerve has definitively lost
witnessed
it
one minute nearly half-an-hour ago, and you
for
then saw that the " excitability
ished
applied
I
i.e.,
with
and about 12 percent, of
what extent may you argue from
a naked tag of nerve to the complex human organisation?
We shall
have
seen
effects
that
there
is
;
We
a similarity between the
of anaesthetics on a
living organism
some
not settle these matters off'hand.
living nerve
our next task
will
and on a
be to examine
of the cases in which their effects
differ.
ANIMAL ELECTRICITY.
LECTURE
I.
25
HISTORICAL NOTE.
Animal electricity " {i.e., the electrical phenomena maniby animals), is now a century old. In its biography
the names of Galvani, Volta, Aldini, Matteucci, du BoisReymond, Hermann, and Bernstein, stand out as the principal marks, together with three somewhat bitter but fruitful
controversies between Galvani and Volta (about 1794), between Matteucci and du Bois-Reymond (about 1850), and
between du Bois-Reymond and Hermann (about 1867).
"
fested
An admirable account of the Galvani v. Volta polemic is
given by du Bois-Reymond in his " Untersuchungen iiber
Thierische
Elektricitat "
(Berlin,
favourable
verdict there
passed upon the part played by
Aldini
in
1848-49-84),
"these troubled waters,"
is,
in
my
but the unopinion,
not
borne out by the evidence.
"
Animal
electricity "
may
be considered as having taken
by Luigi Galvani (or, according
wife Lucia), of spasms occurring, to
origin from the observation
to
all
some
writers,
by
his
appearance spontaneously,
in
the legs of frogs prepared
and suspended by copper ("copper" in 1791,
"iron" in 1786) hooks to an iron railing. Did the act of
discovery arise from Luigi or from Lucia ? Which of them
on noticing the frog twitch first said " ecco " might be
interesting to know, but is of little moment.
There are,
for the kitchen
!
however, certain points relating to the Galvani household
that call for mention.
At this period, Aldini, a nephew of
Galvani,
who was
his studies in the
professor of Physics in 1793, was pursuing
University of Bologna, and was living in
Galvani's house.
The memoirs bearing on
De
the subject are
:
motu musculari
1.
Galvani.
2.
commentarius. Bologna, 1791.
Do., ristampate a Modena, 1792, con note e una dissertatione del Prof. G. Aldini (De animalis electriccX
theorke).
viribus
electricitatis
in
ANIMAL ELECTRICITY.
26
LECTURE
I.
3.
Deir uso e
4.
Anonymous. Bologna, 1794.
Bologna? 1794.
Do., Supplemento.
The two representative experiments are
dell' attivita dell'
arco conduttore nelle con-
trazioni dei muscoli.
:
The contraction with metals.
2. The contraction without metals.
The principal difference between Galvani and Volta was
1.
that according to the former the contraction with metals in
the circuit, was due to animal electricity conducted by the
metal, while according to the latter
by ordinary
tion
The
metals.
electricity
it
was due
not prove the
with metals did
contraction
to an excita-
aroused by contact of dissimilar
This could only be done by
which none but animal tissues were in
existence of animal electricity.
an experiment
in
origin of " Animal Electricity
fixed at the " contraction without metals."
Thus the
circuit.
This experiment
is
mentioned
first
in
"
becomes
anonymous
the
Trattato of 1794, not in Galvani's Commentary of 1791.
Who was the author of the anonymous " Trattato," and
was the author of the " Contraction without
metals"? Aldini in his "Essai sur le Galvanisme " alludes to
But there is nothing to indicate
the experiment as his own.
whether Aldini or Galvani was the author of the Trattato.
who
therefore
On
"
the other hand, Gerhardi
Opere
Bologna,
ed
edite
1841,
inedite
and
del
in
his annotations to the
Professore
Du Bois-Reymond
Elektricitat," unhesitatingly attribute the
in
Luigi
Galvani,"
"
Thierische
his
anonymous
Trattato,
including the important experiment, to Galvani alone as the
"
vero ed unico autore."
The manuscript of this
Reymond to be preserved
at
the
Bologna, and to be
in
Galvani's
partly in
another's
With regard
probabilities,
to
partly
Trattato,
handwriting,
this,
and these
we
in
is
not
are therefore
my
said
by du Bois-
University
Library of
handwriting and
now to be found.
thrown back upon
opinion, indicate at least a joint
authorship of the Trattato, certainly not the exclusive authorship of Galvani, and certainly not a plagiarism by Aldini.
ANIMAL ELECTRICITY.
— LECTURE
27
I.
In 1794 (the date of its publication) Galvani was 57 years
of age, professor of obstetrics and rector of the University
having previously held the chair of Anatomy, and published
the following memoirs de Ossibus 1762 de Renibus 1767
de Manzoliniana Supellectili 1777; de Volatilium aure 1783
:
;
;
;
and de Viribus
Electricitatis in
motu musculari Commentarius
1791.
While at the same date Aldini his nephew, who had long
been a member of his household, was 32 years of age, and
professor of physics in the University.
his Dissertation "
De
In 1792 he published
animalis electricae theoriae ortu atque
In 1796 it is he who demonstrates the new
experiments to Napoleon during his Italian cam-
incrementis."
electrical
paign, and
it
is
to Aldini, not to Galvani, that
all
Volta's
was addressed.
controversial correspondence
Matteucci's contributions to the subject are numerous and
scattered
—
in
French and English
Italian,
"
His
time, 1830-50.
des Animaux," Paris, 1840,
du Bois-Reymond, was the
"
literature of the
Phenomenes electriques
placed by Miiller in the hands of
Essai sur les
starting-point of the latter's
life-
was expanded to a " Traite des
phenomenes electro - physiologiques des Animaux," Paris,
1844, and to his "Cours d'Electrophysiologie," Paris, 1858.
Matteucci's permanent legacy to the subject is " the Secondary Contraction " described by him in the Philosophical Translong labours.
This
Essai
''
actions of the R. S. for 1845, under the
title
of
"
The induced
by du Bois-Reymond to an excitaof the secondary nerve by the negative variation of the
contraction," and referred
tion
primary muscle.
The differing points of view of the two men are thus given
by du Bois-Reymond in the Preface of his " Thierische Elektricitat": "According to him [Matteucci] there are no elec" trical currents in the nerve.
The
muscle-current circulates
" in the
muscle only after certain modifications due to pre"paration, and is in no relation with its contraction.
The
" so-called nervous principle is to him from first to last a
" special
hypothetical
mode
of motion, which he chooses to
ANIMAL ELECTRICITY.
28
"
— LECTURE
I.
represent under the figure of the ether vibrations, holding
it,
"
under all conditions, absolutely distinct from electricity. I,
on the contrary, am in favour of a diametrically opposite
"view.
If I do not greatly deceive myself, I have succeeded
" in realising in full actuality (albeit under a slightly different
" aspect) the hundred years' dream of physicists and physio"
" logists,
to
wit, the
identity of the nervous principle with
" electricity."
Yet du Bois-Reymond was no vitalist
his animating
thought was to analyse the "vital forces" and to find their
physical and chemical components.
His endeavours con;
centrated
themselves upon
muscle, of their electrical manifestations
laid,
perhaps, undue
presenting them
as
stress
and
the study of living nerve
upon
these
in
He
particular.
manifestations
evidence of an identity between
nervous principle and electricity.
by
the
In his view a filament of
nerve was a string of dipolar electromotive molecules, positive at their
middle and negative at their two ends; between
longitudinal
(current
and transverse end a current exists
which undergoes a diminution (negative
surface
of rest)
variation) during excitation of the nerve or of the muscle.
In the electrotonic state (Lecture V.) the molecules are readjusted with negative poles towards the anode and positive
poles towards the kathode.
Hermann's presentation of matters
in several particulars.
differs
from the above
Electrical differences of potential
do
normal nerve or muscle, but are the consequence of injury and of physiological activity. Injured
Physiologically
points are electronegative to normal points.
not pre-exist
in
active points are electronegative to resting points.
negative variation
is
an action-current.
tonic currents are the effect of electrolysis.
Du
Bois'
Du
Bois'
electro-
ANIMAL KLECTRICITV.
— LECTURE
29
I.
REFERENCES.
The
controversy between du Bois-Reymond and
is
through several
scattered
mond's case
is
Du
memoirs.
Hermann
Bois-Rey-
given in his Gesainnielte AbJiandlwigen,
Leipzig, 1877, p. 319 (reprint of paper of 1867).
Hermann's case is given in his Handbuch der Physiologie,
A
vol.
ii.,
vol.
i.,
235 (Leipzig, 1879).
p.
compromise between the two theories
proposed by
Untersuchungen aus dem PhysioiogiscJien
Halle, 1888, reproduced in Bernstein's LehrbucJi
Bernstein
Institute
is
in
der Physiologie (1894), pp. 359, 449.
ture of the whole subject is given
The newer
in
litera-
Biedermann's
jtndi, 1895, English translation by
Macmillan & Co. The theory of the
" current of injury," or "demarcation current," was first
given by Hermann in 1867, and is very fully described
Eiektrop/iysiologie,
F. A.
in his
The
Welby
:
Handbuch der
Physiologie, vol.
i.,
p.
235.
negative variation of the currents of muscle and of nerve
was discovered by du Bois-Reymond
Elektricitdt, vol.
i.,
p. 425).
It is
now
in
1843 {^Thierische
frequently referred
to as the " current of action^
The
of
very
extensive
one.
the best general accounts of the subject
may
literature
Among
anaesthetics
is
a
be named Claude Bernard's Lecons
siir les Ancesihetiqiies
"
"
sur VAspJiyxie, Paris, 1875, and Snow's
(edited by Richardson), London, 1858.
et
Chloroform
LECTURE
II.
CONTENTS.
Dead-beat
Illustration of Ohm's law.
Alcohol, soda water, tobacco
and oscillating magnet.
smoke. Carbonic acid. The function of respiration. InAction of carbonic acid in
tegration and disintegration.
Description of method.
further detail.
The
all
value of experimental results depends above
upon the method by which they may have been
obtained, and the great end of any
shall stringently insulate
sibilities
the particular
observed, and
It is
of the
first
if
method
is
that
it
from amid a crowd of pos-
phenomenon
to
be qualitatively
practicable, quantitatively measured.
importance that the method of inquiry
should be precisely given,
for
that
method
gives
measure of the degree of simplicity and therefore of
cogency
to
have been
And
which experimental analysis and
criticism
carried.
short of
even
this,
for the simple interchange
of information, such as students of particular branches
of science might desire from each other,
that the
reads his
instrumental
little
bit
clearly understood.
it is
necessary
means by which each expert
of natural
knowledge should be
Each province of knowledge has
ANIMAL ELECTRICITY.
indeed
its
verbal,
and
own
language,
3
II.
instrumental
as
I
as
well
only happens too often that students of
it
phenomena
closely allied
LECTURE
to
fail
exchange
no
lights for
other reason than that they do not understand each
other's jargon.
The
dullest
language are generally the
steps in a
first
and most
repulsive,
but
only
by reason of
those steps taken does any language bear
message
its
Where can be the interest of black marks on
paper if we cannot read them, or of a spot of light
wanderino- alono- a scale if we do not know what it is
to us.
saying.
"Current," "Pressure," "Resistance," "Galvano-
some of the
meter," are
some meaning
proceed
a
ABC
labels that
must have
we may be permitted to
otherwise than as sham
for us before
step
further
students.
Well, these labels havino- a meanino- for us
not say their
next ask you
full
to
and complete meaning
make
meant by saying
sure that
—
I
—
do
I
should
we understand what
that "current varies
is
with pressure
and inversely as resistance," and then being sure of
my
ground,
I
should invite you to follow
me
in
the
not very complicated details of the special case here
figured.
The
central object
is
pairs of electrodes, inside
the nerve, lying upon two
a glass chamber, through
which gases and vapours can be driven.
must not
dry, therefore gases
are
made
The nerve
to
pass
in
ANIMAL ELECTRICITY.
32
through a wash-bottle half
the
T
electrodes
L
and
LECTURE
II.
Through
of water.
full
of
injury
of
current
the
the otherwise undisturbed nerve passes to the key-
The
board.
other
connected with an
of
pair
induction
coil
;
are
iyExc.^
electrodes
a circular com-
mutator revolving once a minute sets up excitation
and each time
happens there
at
minute
is
a negative variation of the current of injury.
intervals,
this
A
reverser enables the direction of the exciting currents
to
be changed at
will.
The keyboard
made up
is
of four keys,
nected with the nerve, K3 with
K^ con-
a galvanometer, K^
with a compensator, K^ with a second galvanometer.
When
four keys are closed, the board
all
When
a square of metal.
made by which
When
square.
made by which
K^
in addition
K3
the
is
square,
is
are
On
same
opened, a standardising current
the
into
is
principle
is let
into
and thence through the nerve and the
such galvanometer
if
need be the fourth key, K^,
in use,
K^
is left
;
if
there
is
is
no
closed.
galvanometer, by which your nerve currents
measured,
system of
mirror,
is
out of the
let
the
connected with a second galvanometer
are
let
opened, a mouth
the nerve currents are
galvanometer, and
The
simply
opened, a mouth
the nerve currents
square to the galvanometer.
when K^
is
is
little
which
The nerve
consists
essentially
magnets fixed
reflects
a
beam
of
to the
a
suspended
back of a
light
of light on to a scale.
currents traverse a coil of fine wire sur-
ANIMAL ELECTRICITY.
LECTURE
IL
^erj:i:^^
Fig
io.
Plan of Apparatus.
(This figure
is
repeated on a fly-leaf at the end of the volume.)
33
ANIMAL ELECTRICITY.
34
LECTURE
II.
rounding the magnets, deflect them, and with them
beam
mirror and
the
and
left
on the
amount of
amount of
which
deflection,
with a horizontal
;
light
replace
the
moves
and
right
by a screen
scale
arrange a photographic plate
slit,
descend vertically behind the screen, darken the
to
galvanometer room, and your pointer of
its
right
an indicator of the
is
The
current.
moves
hght which
serving as a pointer to the
scale,
on the scale
left
of
mark, and
all
its
makes
light
movements come out on the
developed plate as black
lines
on a clear background
;
you have a recording galvanometer.
It
is
a great convenience to have such
strument by
coils
itself in
and keys and moving people, and
started.
what
is
But
going
it
on.
is
happening
a scale
in the
in the usual
it
is
This
is
K^,
effected
well
once adjusted
also very convenient to
galvanometer attached to
is
in-
a dark room well away from
to leave the recorder severely to itself
and
an
know
by a second
upon which
all
that
dark room can be watched on
way.
The
resistance in circuit
added by the second galvanometer
that of the bit of nerve between
T
is
of no moment,,
and
L
is
already
100,000 ohms, that of the second galvanometer
is
perhaps 10,000.
In the figure the galvanometer (and mirror) are
as
if
you.
viewed from the back, the sensitive plate faces
Imagine K^ and K3 open, so that the nerve
current passes through the galvanometer, and trace
A^NIMAL
ELECTRICITY,
T
the current from
S
be from
wise
N
be from
I
am
to
that
find
will
the
35
will
it
galvanometer,
negfative variation from
L
like-
T
to
will
and when we see the record that
S,
convenient and natural that the plate
be turned to show deflections up and down
should
instead
of
left.
The
neo-ative
downwards, the current
reads
negative
and
riofht
reads
then
through
you
II.
about to take during the next half hour, you
realise as
will
to
variation
which
it
is
upwards.
have not yet noticed the apparatus connected
I
K^
with
you
the
that
N
to
L,
to
— LECTURE
for
"Graduation
readily appreciate
will
or
its
Compensation," but
use
if
you know that
current increases as pressure and inversely as resistance.
Take a
case like this
ment with carbon
you have made an experi-
:
dioxide, let us say,
and on measur-
ing out the record you have a negative deflection of
10 before and 20 after carbon dioxide.
The
current
has doubled, but this might be by doubled pressure
or
by halved resistance, or from a mixture of the
two changes.
You do
you would do so
at
once
parison the deflections
before and
pressure
not
if
know where you
made by a convenient standard
after
carbon dioxide.
If
known
they
to
be
and the augmented deflection was due
to
pressure only.
be able
but
you had as terms of com-
were found equal, then the resistance
unaltered,
are,
to,
And from any
correct
for
is
inequality you
resistance.
If
the
would
standard
ANIMAL ELECTRICITY.
36
had
deflection
— LECTURE
from 10 to 9 then your deflection
fallen
20 indicates a pressure of 20
from 10
to
if
it
we
volt (for muscle
^-^
the retina by
volt, for
pressure of the
risen
cell
is
—
volt,
i
shall take
Say
volt).
enough
any
at
resistance of the
it
that the
be done by
this will
taking two resistances in the proportion of
(large
had
convenient to take as a standard
is
it
the deflection by
,-^„
",
'-^,
For nerve,
by
x
then the deflection 20 indicates pres-
12,
X
sure of 20
II.
i
and 999
rate to let us neglect the internal
connecting the
cell),
with the two
cell
extremes, and the key K^ with the two ends of the
This
smaller resistance.
because the difference of
is
pressure at the two extremes being
volt,
i
and
falling
progressively from beginning to end in proportion with
resistance,
if
we
two points (say
take a given resistance between any
ohm),
i
we
shall
have a difference of
pressure between those two points equal to
^ of the
For
Leclanche
our purposes
cell
sistances (i
\
it
will
be
(assumed as 1*45
and
1
sufficient to take
volt)
and fixed
volt.
4 ^SO ohms) to deliver -^
1000
I
'
as a matter of practical convenience,
which
found a convenient ear-mark for reading our
we
shall put
up connections so as always
standard deflection
left
or
or
ggg
between the two extremes
total
all
+
,
in
S or negative
one direction,
viz.,
side of the scale,
i.e.,
a
re-
And
will
be
plates,
to take this
towards the
downwards
on the completed record.
The
usual
way of measuring
pressure or potential
is,
ANIMAL ELECTRICITY.
LECTURE
however, by compensation, and you may,
use the resistance boxes r
have only
R
3/
II.
desired,
if
You
for this purpose.
to see that the current
from r opposes the
nerve current at the keyboard, and by successive
value of
that
find
,rq!^,
at
through the galvanometer.
which there
The nerve
no current
is
current
Say,
scale-pan.
when
Leclanche
is
^^
cell
at
0"0i5
that the nerve current
e.g.,
is
,-^-
current
balanced by an equal weight
is
then
i
one
in
another
in
is
then
is
compensated or balanced just as a given mass
scale-pan
trials
balanced
—taking the pressure of the
— the pressure of your nerve
volt
'5
volt.
has been customary to take observations of the
It
excitatory changes (negative variation, &c.) of nerve,
with such compensation
observations this
such as these
current
in the
it
in its
;
nerve
is
is
force,
its
for
rheotome
for observations
a mistake to use a compensating
we have opposing each
the injury current from
the compensator current from
current has
and
But
necessary.
presence
{a)
in
anode
at L.
L
We
to T,
T
to
L
and the
other
;
{U)
latter
shall find later that
a foreign (polarising) current increases the zincability
of living
The
tivity
nerve at
its
point of entrance or anode.
negative deflection due to excitation and zinca-
aroused at
L
reinforced by what
we
tion increment of the
^
therefore unduly exaggerated
is
shall recognise as the polarisa-
compensating current.
See below, the polarisation increment,
p. 135.
ANIMAL
38
We
II.
neglect compensation, and
shall therefore
the nerve current
-LECTURE
ELECTRICITY
so large as to send the spot
is
scale" or "off plate," readjust the deflection by
of a controlling
case of
We
Thomson
shall
r
sistances
tion increment.
(Kelvin) galvanometers.
when we come
We
the nerve, pressures
shall
do
this
means
as that fixed above the
magnet such
have yet another use
R
if
" off
to
make
of the re-
to study the
polarisa-
shall then require to deliver
of,
say,
ot,
0*2, 0*3, &c., volt,
to
and
without altering the connections, by ad-
justment of the resistances,
I
the
will illustrate the
use of these resistances, and at
same time give an example of the
principle that
and
deflection (by current) varies directly as pressure,
inversely
as
experiments.
by
resistance,
This
Fig.
is
II.
the circuit
—A
not be separately put up;
superfluous keys K^ and
fig.
10,
the
following
(fig.
11);
pair
it
of
need
Compensator.
it
is
sufficient to close the
K^ of the
circuit as
leaving only K3 and K^ open.
given
in
ANIMAL ELECTRICITY.
I
R
take r small and
will
LECTURE
IL
39
large, so as to take
R
as a sufficiently accurate denominator of the fraction
R
Taking-
^R,
successively
at
i,
deflections are
100,000,
200,000,
i^,
2,
4,
2,
i,
4 ohms, and
say,
at,
300,000, 400,000, the
i.e.,
as
i,
that
r
the
current varies directly
i.e.,
4,
3,
you see
4 ohms,
3,
Taking r
as pressure.
are
i,
2,
and
100,000 ohms.,
say,
at,
\, i.e.,
\, \,
inversely as resistance, which you
R
at
deflections
current varies
may
recognise as
an instance of the fundamental principle known as
Ohm's Law.
Fig.
12.
(partially
The
— Records
of
deflections
by the dead-beat and by the ordinary
damped) galvanomeler.
time-records are in quarter-minutes; the
beat magnet
is
about 15 seconds;
plete oscillations in
i
minute,
i.e.,
of the
"falling time" of the dead-
partially-damped magnet
has 7 com-
an oscillation period of 8j seconds.
In the galvanometer
movements
the
now
work before you the
at
magnet are
damped
partially
;
see that at each deflection the spot swings to and
above and below
its
position of rest,
diminishing oscillations.
Many
by a
of the
you
fro,
series of
records
you
ANIMAL ELECTRICITY.
40
LECTURE.
II.
have seen have been taken with a galvanometer of
character
this
damped
others have been taken with a fully-
;
magnet
or dead-beat instrument, in which the
comes slowly
to its position of rest without overshoot
or oscillations.
Each
instrument
the
adapted
by
plicated
nerve
an
oscillation
oscillation to
is,
and
say,
electrical
change
abruptly,
will
in
or about
07
more
and
is
sensitive,
and
;
fro,
for
uncom-
effects
The
time of
or " oeriod " of the partially-
and the range
double that of the next swing,
A
2.
is
lasting
the
an
and ending
seconds
instrumental after-
direction
of,
say,
And
swing.
original
i.e.y
by
caused
swing,
four
opposite
the
the
in
after-effects
each other.
be followed by an
of
duration,
short
of
say, eight seconds,
is,
"decrement"
deflection
dis-
effects
supplement
damped magnet
the
advantages and
show more prolonged
they
of a swing
show
to
to
latter
its
The former
advantages.
best
has
if
^,
the
change, instead of ending abruptly, either goes on
of the
same
after-change,
way
character, or give.s
we
shall
have the
to
an opposed
after-oscillation either
checked and reduced, or helped on and augmented.
If this reduction or
we
shall
augmentation
be justified
in
is
very pronounced,
saying that within the four
seconds immediately after an excitation has ceased,
the after-state of the nerve has been like or unlike
its
state during the excitation.
lay too
much
stress
on
slight
It
would not do
alterations,
to
but coarse
ANIMAL ELECTRICITY.
alterations such as those
LECTURE
exempHfied
4T
II.
in figs. 26
and
27 are not ambiguous.
With a dead-beat magnet, which moves
as
plunged
if
The
different.
a sticky
in
time
Any
it
is
of an
the after-state
state.
It is
are
quite
" rising
"
or " falling
"
time.
it
may
to
a position of rest at the
effect,
receive
lost
;
and
show whether
not
will
it
is
positive or negative to the previous
is
only
the after-state
if
comparison with the
that the
we
back
falling
termination
in
is its
brief impulse that
while
matters
fluid,
takes to pass from one posi-
it
tion of rest to another
sluggishly,
magnet
will
is
very prolonged,
falling time, fifteen
indicate
its
seconds,
presence, and then
practically only get signs of the after-state
from
the end of the falling time onwards.
Thus, however, the two kinds of magnet supple-
ment each other as witnesses
;
both indicate the state
during excitation, the swinging magnet indicates the
immediately
state
magnet the
after
the
excitation,
dead-beat
state during a later period after excitation.
Let us now turn to perhaps more familiar matters,
and make use of
this
apparatus to test the effects upon
nerve, of alcohol, soda water and tobacco smoke.
A
nerve
chamber
is
lying
(fig. 10).
soda water,
spot
is
all
at zero.
upon
The
its
electrodes in the moist
wash-bottle
is
half
full
of fresh
the keys are closed, the galvanometer
I
open K, (from the nerve) and K3
the galvanometer) and the spot
moves
(to
half across the
ANIMAL PXECTRICITY.
42
What
nerve.
the
L
and
r^
volt
o-ives
coils,
Now
deflection that
chamber
this
am
I
not
is
answer.
i.e.,
much
Is
^
o'oois
unaltered
to
;
We
o-reater
let
minute
it
due
deflection
The
?
soda
after
but a minute later
is
to
it
augmented
raised
standard pres-
deflection
is
due
go through the same steps with tobacco smoke
And now
we
will
precisely similar
is
previous experiment.
in the
is
a stimulant.
to bring these trivial
experiments to a
try the effect of strong alcohol, driving
The
The
vapour as before into the nerve-chamber.
response of the nerve
is
promptly abolished.
nerve seems to be dead, but
"
is
not to diminished resistance.
pressure,
Like soda water, tobacco smoke
than
is
about
by opening K^
into the circuit
even more marked than
its
for the
deflection
first
on a fresh nerve, and the result
close,
by a pres-
into the nerve-
it
at the third
therefore the
augmented
Now
volt.
The
altered,
and
this
volt
is
a fairly good one
It is
pressure or lowered resistance
sure, of
find that
us start the excitation by
passing air through
distinctlv laro-er,
doubled.
let
one minute.
for
?
questioned, and watch the negative
is its
about li deoTee.
water.
is
current
and
current of injury that gives 8 degrees,
which the nerve
L
decree deflection, therefore the
i
sure of ^' volt.
to
pressure
giving that
open K, from the graduation
the:
T
value of the
the
is
T
between
difference
I
IL
by reason of the current of injury from
scale
in
LECTURE
dead-drunk
"
;
I
is
have
in
little
reality
doubt
no more
of
its
ANIMAL
Fig.
13 (2466).
ELB;CTRICITY.
— Effect
of
LECTURE
"soda water" upon
IL
43
the electrical responses of
isolated nerve.
The
The
by ToVo
vertical
dark bar indicates when the "soda water" acts on the nerve.
deflections at beginning
and end of the
series are standard deflections
volt.
Fig. 14 (2464).
— Effect of alcohol vapour (ethylic alcohol,
ElOH).
i
.%.••
n \!
)!
i
1
i
f
Li
-i
!M
Fig. 15 (2468).
hours
later.
— Effect of
tobacco smoke on the same nerve (2464) twelve
ANIMAL PXECTRICITY.
44
LECTURE
IL
recovery within a few hours, almost certainly by to-
morrow morning.
Let us pause now
to consider the effects of these
experiments, which are chosen on purpose to
three
enforce the principle insisted upon at
my
last lecture,
that living matter in the shape of a nerve,
us
some
may
give
clue to the action of drugs on the living body.
The soda water has
acted evidently by reason of
dissolved gas, which
is
smoke has very
carbon dioxide.
active, since
I
have not yet
Alcohol (that
its
I
am
not prepared
is
is
tried the effect of tobacco
CO^.
to say ethylic alcohol,
EtOH we
;
on some future occasion have something
about other alcohols) has,
as
still
;
same
no other constituent of tobacco smoke
smoke deprived of
shall
tobacco
acted by reason of the
likely
constituent, carbon dioxide
to say that
The
its
in
to say
way we used it, acted
If we had been very
the
a profound depressant.
we might have witnessed on the nerve its
preliminary exhilarant effect.
As to how it acts, I
do not wish to be positive, but may remark that it
careful,
not improbably acts by depriving the nerve of water
— the
effects of alcohol
much
alike,
vapour and of drying are very
and so indeed
is
that of prussic acid
point that might perhaps be very effectively
of
by a temperance advocate.
would probably omit
to
—
made use
But such a person
comment upon
the effect of
pure water, which very promptly puts an end to the
nerve.
Here, however,
we come
to a point of diverg-
ANIMAL ELECTRICITV.
ence between the
— LECTURE
45
of nerve and the entire organism
bit
pure water has certainly no such toxic
it
IL
on man as
effect
has when directly applied to one of his tissues.
Of
the several materials just alluded
the most interesting and important
dioxide.
I
in
fell
It
into
has perhaps been a
the investigation, for
great,
the
hints
its
dioxide
vented
claimants upon
other
all
me from
it
an inquiry
is
been
my
the
which
in
infancy
the
mode
could
I
number
of
period
of
necessary preliminary to
and deeper analysis of the
so
and pre-
time,
pursuing as extensively as
reagents
early
has crushed out
wish that superficial survey of a large
chemical
so
allurements have been so
significant yet so mysterious, that
nearly
unfortunate that
little
vouchsafed have
has
it
far
the gas, carbon
is
hands of carbon
the
by
to,
further
of action
of
a
few chosen substances.
considering
Nevertheless,
one of the two
all
living
disintegration
principal
matter
—the
carbonic
that
vehicle
of
export of carbon from the organism
—
acid
is
products
of
the
respiratory
that
it
produces
with unmistakeable clearness effects that might have
been predicted a priori were we only endowed with
sufficient
imaoinative wit
from these data we
as to
shall
;
considerinof
further,
that
be able to draw inferences
the existence and nature of physical changes
effected within the nerve
ences to the
test
itself,
and put those
of clear-cut experiment,
I
infer-
cannot
LECTURE
ANIMAL ELECTRICITY.
46
regard
much time
matter for regret that so
as
it
11.
should have been necessary to investigate
acid at
And
thoroughly.
all
two years
after all
not so very long, but the investigation
its
carbonic
is
is
not near
end.
Let
me
entering upon any
at once, before
analysis, exhibit to
you two observations that represent
the regular and typical action of carbonic
nerve.
The
close
upon
two figures shows that
of these
first
acid
carbonic acid in small quantity acts as a "stimulant."
The
next figure shows that carbonic acid
as a narcotic.
quantity acts
anaesthetic
— excitant when
when
depressant
It
to
of carbon
matter,
to
if
action
order
dioxide in
me
of the
I
to
the
invite
you
recognise
economy of
the view
respiratory
you
function.
It
a few years ago to overhear a con-
versation in a conservatory between a
man and
a typical
ly).
(fig.
at this stage
in
large
slight (fig. i6),
is
complete
is
fact
in
is
and perhaps broaden
may have formed
happened
its
digression
a brief
relations
living
action
not be amiss
will
make
the
its
It
in
a young lady.
They were
young gentlediscussing the
and the two disputants (they were of quite
tender years, nine and eight respectively) took up
plants,
what struck
man-child
could they
child
said
The
"of course plants breathe, how
said
the womanlive if they didn't breathe "
"of course plants don't breathe, how
me
as
very typical standpoints.
can they breathe without lungs."
;
Well, of course
ANIMAL ELECTRICITY.
Before.
CO^.
LECTURE
II.
After.
Fig. i6 (674).— Effect of "little" COo.
Primary Excitation.
After
CO,
Fig. 17 (627).— Effect of " much " CO,.
Secondary Excitation.
Complete Anesthesia followed by
47
ANIMAL ELECTRICITY.
48
woman
the
man was
do
and
right,
gave
evidence,
We
our personal friends
all
by
breathe
fishes
II.
got the best of the argument, but the
superior imaginative power.
so
LECTURE
gills,
and protoplasm, devoid though
of
breathe by lungs,
among
animals
by
breathe
plants
think,
I
it
;
but
leaves,
be of diverse parts
or organs, breathes by direct take and give between
and
itself
the
w^here
units
living
atmosphere, lungs or
intermediate
the
are
And
atmosphere.
the
gills,
heart vessels and blood
instruments
give between protoplasm and
directly or indirectly, takes
gives
tion
to
is
the
air
organism
away from the
buried
are
an
in
take and
of this
Protoplasm, then,
air.
from the
air
oxygen, and
carbon dioxide, and such respira-
the primitive essential function to which the
instrumental
means
— organs
of circulation
—are
secondary and accessory compli-
cations.
It
of
respiration,
-^
It
has been said that "respiration
bustion,"
organs
a slow com-
is
and Black, a century and a half ago,
fifty
years before the discovery of oxygen by Priestley, and
the
identification
closer
respiration
with
combustion, showed that
product of respiration
bustion.
by the Lavoisier school of
And even
is
the
end-
identical with that of
com-
to-day,
if
we bear
in
mind
that
the carbon dioxide produced by respiration (as indeed
that
produced by combustion)
direct oxidation
— that
is
not
a product of
carbon and oxygen do
not, so to
speak, meet and join hands directly, either in the lungs,
ANIMAL ELECTRICITY.
LECTURE
and straightway run
or In the blood, or in the tissues,
down
is
together
hill
—
think the phrase "respiration
I
a slow combustion
49
II,
"
is
Oxygen, the
permissible.
incoming "food"
—
diately necessary
"food" than water, bread and meat
for
oxygen
climbs a mountain where
first
member
of that mysterious
are the expression of
non of
its
its
The immediate
chemical change
which
at
Living tissue
is
heat which
is
that
a sine qua
the
is
its activity.
antecedent of physiological activity
—a
disintegration of "inogen," of
is
carbon dioxide.
deoxydative or reducing towards the
oxygen- yielding blood by which
at the
call
which by acting
body movements
one end-product
least
we
and carbon dioxide which
action,
token and measure of
is
life,
of atoms
to act,
are expended, yielding to the
a
lost to view, as
is
it
company
have power
"proteid,"^ which
even a more imme-
is
it
is
traversed
same time oxydative and synthetic
the formation of
its
own working
;
it
is
as regards
balance of inogen,
deoxydative and analytic as regards expenditure of
that balance.
It is
a
imports equal exports
organism and
maintain
to
itself
maxim
;
of political
a similar
maxim
economy
applies to the
any portion of the organism that
in
the
physiological
that
economy.
is
to
If
a
Perhaps it would be better to say " inogen," in order not
seem to prejudge the vexed question whether the forceproducing compound that disintegrates is proteid or carbo^
to
hydrate.
4
ANIMAL ELECTRICITY.
50
LECTURE
II.
muscle works and does not diminish, carbon and oxy-
gen must come
to
as carbon with
it,
oxygen leave
There must be integration reparative of
And
tion.
action the disintegrative
disintegra-
doubt during heightened
no
although
it.
movement
is
hastened, and
during subsequent repose reintegration, yet
we must
not too absolutely imagine as independent and dissociated these two opposite
movements
— they are rather
concomitant aspects of one complex process of
the
metabolism, although, no doubt, action gives promi-
nence to the negative movement of expenditure, and
rest favours the positive
Turninor back
action,
as
it
we
movement
the
to
of recuperation.
electrical
find this opposition of
sig^ns
of
movements mirrored
were by the currents during and
after action.
During action we have a negative
effect, after
we have
To which
statement
a
I
positive
after-effect.
may add
nerve
action
double
that in certain states of nerve
we may witness even during action a positive effect
that may possibly signify that even during action
integration may predominate over disintegration.
But however that may be, we shall find in the
empirical study of reagents that this positive variation contributes
series
of
some very
significant
arguments upon which we
items
are
to
the
about to
enter.
To sum
up,
we
shall
have as elements of study
three principal effects upon a nerve set up for experi-
ment
as
shewn
in fig. lo.
ANIMAL ELECTRICITY.
(i)
due
The
LECTURE
II.
5
I
negative variation of du Bois-Reymond,
to disintegrative activity at L.
(2)
The
positive
movement
to reintegrative chemical
(3)
The
due
Hering,
of
after-variation
at L.
positive variation to which
I
have alluded
above, present only in certain states of nerve,
butable
augmented
activity at L.^
In the
case zincativity at L, deoxidation of
first
inogen, rejection of CO,, acidificatory
In
attri-
movement during
chemical
integrative
to
and
second,
the
possibly
effect.
third
cases
anti-
zincativity at L, oxidation of inogen, deacidification.
But
I
cannot interpret matters at this stage with
any degree of assurance, and
Let
from the attempt.
fact
that nerve
rather emphasise the bare
Here
CO^.
is
a fresh nerve, giving
a by no means impressive response, but
through the
little
refrain
an extraordinarily sensitive reagent
is
to the presence of
me
shall therefore
vessel that contains
it,
I
breathe
and there
will
be a perfectly obvious improvement of the response
within one or two minutes, due to the carbonic acid
contained
in
expired
most sensitive reagent
The nerve is by far
know of to carbonic acid
air.
I
;
the
left
a minute or two in a tube of one cubic centimetre
for
The conceivable changes at T are left out of count there
however, evidence to support the view that the negative
^
;
is,
variation
is
zincativity at
often
L
and
the
sum
of
two homodromous
anti- zincativity at
T.
activities
52
ANIMAL ELECTRICITY.
capacity containing
LECTURE
11.
per cent, of carbonic acid,
i
unmistakeably altered.
Thus
it
has
reacted
hundredth of a cubic centimetre (or about one
of a
miHigramme) of CO^, and no doubt
this
it
is
to
a
fiftieth
has not
been a minimum hmit.
Fig. i8 (598).— Effect of expired air (Excitation by "little " CO,).
In conclusion let
me
place before you the record
of a complete experiment such as that of which
have just witnessed an
an instance of the
initial
effect of
stage.
Plate
you
589
is
expired air in an obser-
vation lasting about forty minutes.
The
series of re-
ANIMAL
sponses to the
LECTURE
ELECTRICITY.
of the hght bar gives the normal
left
expired air was
— the
— and
blown
thirty responses
give token
of this particular nerve
expired
air
the
of the
to
was neither due
anything else
in
CO,, and
altered
this
state of
it
for
CO, and was
two minutes.
was ascertained that the
to altered temperature nor
the expired air but CO^.
then evident that nerve
to
next twenty or
contained 3 per cent, of
other experiments
alteration
when
next twenty or thirty minutes.
blown throuorh the nerve chamber
By
bar shows
light
in
the nerve during the
The
53
II.
clear
is
extraordinarily
fact will
It
is
sensitive
form the point of
departure of our further study.
REFERENCES.
The
general notion of
"
internal respiration," the functional
protoplasm, as distinguished from " external respiration," the accessory means, alluded to on
his Lecons
p. 48, is developed by Claude Bernard in
et
aninianx
sur les Phenomenes de la Vie comvnins mix
The notion of the
aiix vegetaiix, vol. ii., Paris, 1879.
attribute of
all
double aspect of functional changes in living matter,
analysis and synthesis, breakingin the terms
expressed
down and
—
building-up, dissimilation
and
assimilation,
ANIMAL ELECTRICITY.
54
LECTURE
II.
katabolism and anabolism, disintegration and reintegration
—
is
developed at length by Claude Bernard in Pheno-
menes de la
Zur
TJieorie
Vie, vol.
ii,,
by Hering
in "Zc/^j-," ix., 1888,
der Vorgdngein der lebendigen Substa?iz, and
from the particular standpoint of electrical phenomena by
Hering's pupil Biedermann,in several papers summarised
Hering's paper of 1888 is
in his Elektrophysiologie.
translated in the current
volume (1897) of
'^
Brain."
55
LECTURE
III.
CONTENTS.
On
the production of CO, by tetanised nerve.
Hypothesis and experiment. Three stages. Comparison between
the effects of
CO2 and
of tetanisation.
Significance of the staircase effect.
Direction of further inquiry.
" Bahnung."
Summation.
Postscript.
It
was comparatively early
in these
during the month of October, 1895
experiments
—^hat
the nerves
under study presented some puzzling features
mode
of response, that for
came
to
vanished
nerves said
"check,"
month (February) they are again saying
just as this
My
"check."
some time were a grievance
The
and a stumblino"-block.
in their
its
disgust
their
at
enigmatical
conduct
climax on October 27 with plate 672, and
the evening of the
in
same day with the
appearance of plate 675.
for
venture to
I
will
I
think that
it
tell
the story of these two plates,
illustrates
what so often happens
the course of an inquiry as almost to be the rule,
in
viz.,
course of some otherwise smooth
that
"check"
and
glib interrogation, although at first disliked as a
in the
stumbling-block, ought in reality to be welcomed as a
stepping-stone in disguise, a sign that
bit of truth
I
some unexpected
has cropped up.
had undertaken
to
action of carbon dioxide,
show a
friend the stimulant
and had announced
it
as an
ANIMAL ELECTRICITY.
56
unfailing experiment.
a frog
is
cession,
killed
and
I
IIL
had previously noticed that
two
its
LECTURE
sciatic
if
nerves used in suc-
the second nerve always gave larger varia-
tions than the
first.
had also noticed that
I
case of a nerve that had been
left
in the
lying for twelve
hours in the killed animal, the variation was extraordinarily large
But
I
— four
had never
upon such a
or five times
tried
its
the effect of
usual value.
carbonic
variation.
—
Effect of COgUpon a "carbonised" nerve, i.e., a nerve
Fig. 19 (672).
24 hours subject to the reducing action of the surrounding muscles.
Wanting
to
possible with a
make
good
nerve that had been
and got the
to
my
variation to start with,
left
for twelve
result recorded
considerable disgust.
my
friend
left for
the demonstration as clear as
hours
on plate 672
The
took a
I
in the frog
(fig.
19),
stimulant action of
carbon dioxide was conspicuously poor, and
think
acid
watched the experiment
I
don't
out, in fact,
ANIMAL ELECTRICITY.
I
week
57
III.
experiment of which you saw the
recollect that the
record last
LECTURE
i6, plate
(fig.
674) was
made upon
a
fresh nerve immediately after his departure.
Later
in the
day the
failure
(which was the
had met with) came under discussion.
nerve had been very
much
towards carbonic acid.
A
But has
nerve
this
Who
CO3 ?
I
Clearly this
altered in
its
disposition
reducing- action of the sur-
rounding muscles must have been at work
course.
first
CO^
;
of
been only muscle CO^ or also
and how
decide
shall
That
?
question must wait, but the obvious question whether
exaggerated activity of nerve
is
or
is
not attended with
an increased production of CO^ can be tested
since the nerve itself
at once,
such a delicate reagent to
is
A
presence from outside.
little
expired
the nerve by reason of a quantity of
air,
its
acting on
CO^ much below
what can be detected by orthodox chemical
tests,
pro-
duces a great change of the galvanometric response
(see
fig.
18)
;
surely
tetanised nerve,
duced within
it,
if
we
of response.
tion
if
any change takes place within
one single molecule of CO^
shall
have the characteristic
Let us do
this
:
take
is
pro-
altera-
say
five
normal responses, then tetanise the nerve continuously
for five minutes, then take
one single molecule of CO^
we
shall
some more
is
responses.
If
evolved within the nerve,
have an augmented response, diminishing
minute by minute with the disappearance of CO,.
A
blackboard sketch
(fig.
20) accompanied
rather extravagantly expressed argument,
this
and the slope
ANIMAL ELECTRICITY.
58
LECTURE
III.
of the chalk line, indicating the state of things during
the proposed five minutes' tetanus,
was dictated by the
thought that with the imagined progressive evolution of
CO3
there should be a gradually increasing negative
variation, giving a gradually increasing departure
the general base
line.
Such was the
Fig. 20.
when
675
half an hour later,
(fig.
I
watched the
the
series
to
I
be the
my
it
was
found the greater
sole
difference
between the autographic record of the nerve
and
yet,
lines of plate
21) appearing in the developing dish,
of
—
— Hypothesis.
with something of astonishment that
regularity
forecast
from
itself,
rough blackboard drawing.
Well, this
evidence.
is
And
not proof, but
it
considering that
is
very remarkable
we have no
previous
ANIMAL ELECTRICITY.
evidence of
any
nerve,
tetanised
chemical
it
LECTURE
seems
me
to
not
pausing to deal with the criticism that
but " somethino- else" that
has
Moreover, the evidence
change
physical
or
59
III.
worth
it
is
not
in
while
CO^
Qriven the result.
corroborated in a very
is
remarkable manner under a considerable variety of
conditions.
Fig. 21 (675).
But
before
we
are
— Verification.
in
a position
appreciate this further evidence,
it
will
to
properly
be necessary to
enter into a digression, speculative from one point of
view, empirical, however, as regards our experimental
survey of the
effects
of carbonic
acid
acting from
without and presumably acting from within.
The
typical
electrical
freshly excised nerve
is
effect
of excitation
of
a
the negative variation of du
ANIMAL ELECTRICITY.
6o
LECTURE
Bois-Reymond, and the hardly
the
is
positive
after
-
less typical after-effect
of
variation
Hering.
state of nerve after excitation
electrical
III.
is
The
for a short
period the reverse of that obtaining during excitation
and
if
we
call
the latter
former "positive."
"
;
negative," v^e must call the
Here, for example, recorded by a
quite dead-beat galvanometer,
a typical series of
is
negative followed by positive after-effects, the former
Fig. 22 (2177).
undiminishing, the
latter
progressively
That progressive diminution of the
positive after-effect
presently be clear to us as a characteristic change
will
produced by carbonic acid
The
— more so as a
little stale,
I
anticipate.
rule in nerve that
more or
is
less
becoming
or that has been trifled with by previous
experiments.
Sometimes the
pronounced as greatly
that
— but
positive after-effect presents itself
obviously
a
diminishing.
precedes
it.
As
to
positive after-effect
exceed the negative
a matter
of
is
so
effect
convenience
I
distinguish such nerve as being in the second stage.
ANIMAL ELECTRICITY.
LECTURE
6l
III.
neither undoubtedly fresh nor unmistakeably staletransitional in short.
Finally
witness,
it is
not
uncommon
—nor
even during excitation, what
common
yet
I
—
to
have been led
to regard as characteristic of stale or experimentally
maltreated nerve,
viz.,
a positive electrical
has generally prolonged
nounced degree as a positive
excitation,
is
chiefly for
the
for
stages
—
subsequent to
to a negative
this last point
;
indeed,
convenience of description that
moment
empirical,
fresh, transitional,
and
division
stale,
I
into
I
it
make
three
of which the three
characteristic features are respectively
effect, (2)
less pro-
few seconds after excitation.
however, no stress upon
this,
after-effect
and has rarely given place
state during the first
lay,
more or
itself in
which
effect,
—
(i) a negative
a positive after-effect, (3) a positive
effect.^
r>^^^
IL
III.
Fig. 23.
^
I
have argued elsewhere what cannot be argued here, viz.
above referred to has not been produced
that the positive effect
by an ordinary Anelectrotonic current.
LECTURE
ANIMAL ELECTRICITY.
62
III.
Let US now take nerves of these three stages,
types
three
the
respectively
giving
of
electrical
response just enumerated, and examine upon them the
by carbonic
alterations of response brought about
The
produced
alterations
The
already witnessed.
in
transitional
nerve, especially the latter, are under
more uncertain
tion of the
we cannot
desired
it
tion that
may
the worst
make such
result
and
stale
circumstances
all
unfailingly obtain a varia-
and even when we have
type,
— we cannot
obtained
is
;
nerve you have
negative variation was aug-
Those produced
mented.
in fresh
acid.
confidently predict the altera-
And
from our interference.
month (February)
which
in
this
to attempt to
delicate demonstrations.
But the records of past experiments are of equal
value
with
experiments
the
examples already alluded
and
to
which
the regular
all the
now
I
to
return,
and
themselves,
in
my
are
second
the
lecture,
representative
of
of several hundred experiments,
results
records of which
are
indexed and
open
to
your inspection.
Here, then,
is
the effect of
nerve of the second stage
effect is increased,
(fig.
carbonic acid
26).
The
the positive after-effect
upon
negative
is
dimin-
ished.
Here
is
third stage
the effect of carbonic acid upon nerve of the
(fig.
28).
The
and replaced by a negative
positive effect
effect.
is
abolished
ANIMAL ELECTRICITY.
Here
—-LECTURE
63
III.
another and less pronounced
is
carbonic acid upon nerve of the third stage
The
positive effect
is
— either
upon the same nerve, or
activity
is
that
in
at least
artificial
each separate
similar to the effect of
Considering the conditions of the
carbon dioxide.
— that the a
— by prolonged
recognise
will
case the effect of
case
these three typical and charac-
a similar state
in
You
activity.
30).
of carbon dioxide, the effects produced
teristic effects
upon nerve
(fig.
diminished.
Compare now with
upon nerve
of
effect
J>7'io7'i
carbon dioxide, we
probable product of activity
are,
I
is
think, entitled to conclude
that the similar series of effects has been due to a
common
out
cause
—
to
one series
in
evolved from within
itself
;
known CO^ introduced from withto the hitherto unknown CO^
in the second series.
The nerve
has served as
presence of the
Here
the
reagent indicative
of
the
latter.
the nerve giving a small negative deflec-
is
tion followed
by a large
after-deflection,
altered
as
you have seen by CO^ from without, and similarly
altered
figs.
26
consequence
in
&
Here
of
tetanisation.
27).
is
the
nerve giving a positive deflection,
reversed to a negative deflection by
and here
reversal
figs,
28
in
Here,
the
is
&
(Compare
same nerve
CO^ from
without,
a
similar
exhibitiiiof
consequence of tetanisation.
(Compare
29).
finally, is
the
nerve of which the positive
First
LECTURE
ANIMAL ELECTRICITY.
64
III.
Stage.
tthout
Fig. 24 (869).
—Augmented
negative
effect.
Second Stage.
Fig. 26 {710).
— Augmented
negative
effect.
Dimin-
ished positive after-effect.
Third Stage.
Fig. 28 (859).
— Positive
converted into negative
effect.
Third Stage.
Fig. 30 (985).
— Positive
effect
diminished.
Influence of Carbon Dioxide on the Electrical Response of Nerve
IN ITS three stages.
ANIMAL ELECTRICITY.
First Stage.
LECTURE
III.
65
mm*
1
CC,from
within
Fig. 25 (675).
—Augmented negative
effect.
Second Stage.
—
Augmented negative effect (other
Fig. 27 (762).
observations exhibit diminished positive after-effect, e.g.,
%•
33)-
CO^ /ro/>.
Third Stage.
'
III!
I
!
!
>^
^w^'NIs^ 't^^*^*^-^
after
I
Fig. 29 (858).
Third Stage.
— Positive converted into negative
after-effect.
(!!!'!!
^v
m>:i0m':ii
I
i
I
1
ij
Fig. 31 (984). ^Positive effect diminished.
Influence of Tetanisation on the Electrical Response of Nerve
IN ITS
5
Three Stages.
ANIMAL ELECTRICITY.
66
deflection
is
only diminished by
is
the
consequence
30
&
brought to your
of
very
CO^ from
without, and
fatigue
(Compare
last plate
this
if
taken
diminution
to the
be
to
a
effect.
Provisionally admitting as an established
that carbon dioxide
is
datum
one of the products of nerve
our next question
activity,
first
you would
traversed,
the
figs.
had been
and without reference
notice,
have
similar diminution as
tetanisation.
considerations just
likely
common
of
Indeed,
31).
group
III.
same nerve giving a
here
the
LECTURE
is
what becomes of
:
it ?
can venture upon no positive answer to this
I
question.
moment
For the
seems
it
to
me
that
there are two possible answers open to our further
investigation.
It
is
diffusion
may be
I
possible that the
CO^ may be
from the nerve, but
it is
also possible that
reintegrated within the nerve
it
itself.
have not yet found means of deciding between
these two alternatives, which
felt
dissipated by
it
I
unprofitable to state and briefly consider.
Obviously the
first
what more natural
alternative presents itself
fate
can
we imaoine
into
lymph and
for
first
CO,,
;
if
by
dif-
the surrounding atmosphere or into
the
produced within a nerve, than
fusion
have nevertheless not
its
dissipation
blood, as in the case of the
within a muscle
?
I
have nothing
obvious probability, and can
CO^ evolved
to say against this
only point
out
as
a
ANIMAL ELECTRICITY.
remote
LECTURE
III.
6/
possibility,
suggested indeed by one or two
peculiar features in the behaviour of
isolated nerve,
that CO, evolved in the process of
disintegration may
conceivably be reinvolved
tion
;
in
a process of reintegra-
that, in short, baseless as the
present, there
tion of
may
be
in
CO, analogous
taking place
in
idea
may seem
at
an animal tissue an assimila-
with the assimilation of
vegetable protoplasm.
We
have
CO,
rea-
son to associate the negative effect with
a dissimilatory
evolution of CO,, we may some day
find reason to
associate the positive after-effect with
an assimilatory
reinvolution of CO,.
But at present this is a mere
flying conjecture for which I have
no positive base.
Putting this conjecture aside, let us turn
to another
less imaginary, yet still distinctly
conjectural point.
Contractile tissue -that of the heart
in particular,
but also the contractile tissue of
jelly-fish, as well as
voluntary
muscular
known
physiologists as
to
tissue
— exhibits
a
the "staircase
peculiarity
phenome-
non."
Stimulated at regular intervals, not
too long nor
too short, by strong induction
shocks, such
con'trac-
tile
tissue gives a series
of responses, each of which
the greatest effort of which the
muscle is capable at
the time, but each of which is
a little greater than its
predecessor.
Such an increasing series is called
a
is
staircase,
and we have seen that a
series of electrica
responses of nerve exhibits a similar
staircase
increasing in the case of a series
of negative effects,
decreasing in the case of a series of
poskive effects or
—
LECTURE
ANIMAL ELECTRICITY.
68
after-effects.
effect
of
Remembering
CO, from
the
that
without,
III.
characteristic
and presumably from
an augmentation of negative response and
a diminution of positive response, we have no diffiwithin,
is
culty in admitting that the electrical staircase of nerve,
whether ascending or descending,
brought about by
is
carbonic acid evolved at each step in a series.
pretty obviously a
It is
CO^ phenomenon.
Fig. 32.
— "Staircase"
of contractions
of a frog's heart.
m0m
Fig. 32 A.
— " Staircase "
of electrical responses of nerve.
Staircase effect, then,
clearly applies to nerve
tissue,
it
clearly
produced by CO^.
notion
is
definite
effects
not confined to contractile
is
To my mind
a welcome addition
psychological
obtainino' in
Summation of
notions
central
stimuli
lation of a series of
where
to
is
equally
this
precise
it
our somewhat less
concerning
staircase
nervous action.
i.e.,
the gradual accumu-
individually insufficient
into an effective excitant
—
is itself
stimuli
conceivable as the
expression of augmenting excitability by augmenting
evolution of COj.
The
establishment of paths of less
LECTURE
ANIMAL ELECTRICITY.
resistance
nervous system
—
logists
or
this
in
— the
"
some
transmission along
and
nerve-impulses,
our
"
due
a
with
imao-ination
mass
carbonic acid
;
the subsequent
is
conductile
form
of
of action
That
lines.
"
Bahnung
"
within
such
this line,
and
will
will
in
be
my mind
to
the
a knowledge of the
tween carbonic acid and nerve makes
familiar,
relations
this
the result.
there
idea
is
as
more
I
had
mechanism of
there has been a disintegration,
same
line a reinteo'ration of
also
We
functionally constituted.
followed,
carbonic
know
that
acid.
reinvolved in
that
I
one of the products of wear
wonder
does
;
may
this
it
is
;
is
carbonic acid
not perhaps be
some storage combination,
perhaps, that
know
and more than made good, by repair
become altogether dissipated
fat
—
be-
by which the nerve-path becomes organically
as well
we
if
follows alono- the
matter,
wear
And
—physico-chemical
with
sense
concrete and tangible by suggesting a possible
almost said probable
in this
have been a
which Spencer's writings have made us so
and
a
Picture to your-
action
of
within
tissue
evolved along
discharge
rather than in other
primitive
excitability
its
may even be tempted to
much further back — to the
discharge
linear
first
by
We
mass of homogeneous protoplasm.
a
of
facilitation
line previously traversed
very origin of specially
self
central
German psycho-
of
to
therefore
sharpened by CO,.
cast
Bahnung
conceivably
is
the
direction of
that
69
III.
as the nerve-
so prominent a constituent of fully
ANIMAL ELECTRICITY.
yo
Such nerve
evolved nerve.
and
fatty sheath
nerve-cell
is
—
the axis
;
LBXTURE
III.
consists of proteid axis
— which
is
the offshoot of a
the specially conductile part, the sheath
is
a developmental appendix, not directly connected
with any nerve-cell.
well
as
which
as
undergo
axis
evident
is
Yet, cut the nerve, and sheath
proof of a
between sheath and
that such nerve
Wallerian
degeneration,
functional
You have
axis.
seen
inexhaustible, yet that
is
commerce
it
further,
exhibits
very clear symptoms of chemical change after action.
my
these things, to
All
mind, reconcile themselves
with the notion that the active grey
down and
uses up
its
own
fatty sheath,
inexhaustible, not because there
but because there
ture,
This
is
is
—and
imagination
this,
nor claim for
motive for further
it
I
is little
both lays
and that
it
is
or no expendi-
an ample re-supply.
wild hypothesis
the
axis
— an
shall
unbridled excess of
be the
first
to
admit
any value other than as a possible
trial.
leaving aside the imaginary reinvolution of
Still,
CO2 and
the imaginary origin of specially conductile
strands, let
me
urge that the staircase
at least
a general phenomenon gains value
in
effect as
a definite and
concrete sense, both as a physiological and as a psychological idea,
is
when we have admitted
that carbonic acid
a product of nerve activity and that carbonic acid
facilitates
point
it
nerve activity.
seems
factor of
to
me
From
a physiological stand-
preferable to admit as an effective
"summation
"
and of
" staircase effect
"
and
LECTURE
ANIMAL ELECTRICITY.
of " Bahnung," that
which
7
III.
augmented mobility of protoplasm
a characteristic effect of carbonic acid,
is
product of previous activity, than
principal
I
the
say
to
"that excitation arouses a tissue to a state of greater
expectancy as well as of greater activity."
And
in this
connection one
is
tempted
to at least
ask oneself whether the converse phenomena
us as
may
*'
fatigue," the "refractory state,"
effect,
— whether
"inhibition,"
may
not
ansesthetic action, which
its
come
these records.
little
me
briefly
to
do not
answer two questions
have been very frequently put
means
I
enter at present.
In conclusion, let
that
its
But upon the considera-
tion of this negative aspect of nerve activity
feel able to
is
into play with exaggerated
or with culminating activity.
I
will
my own
me
answer them
satisfaction,
with regard to
briefly,
the
for
and by no
answers are
more than counter-questions.
What
tive
to
not also be connected with the evolution of car-
bonic acid
full
known
interpretation do
and positive
What
is
the
effects
you place upon these nega-
?
meaning of
that remarkable alteration
of base-line caused by carbonic acid
As
to the first question,
I
?
ask myself whether the
negative and positive effects are to be regarded as
signs of opposite chemical
neo-atlve
is
to
be taken as a
movements, whether the
sIo;n
of disinteo[-ration and
the positive as a sign of integration, in the sense of
Herine's
dissimilation
and assimilation
—or
whether
LECTURE
ANIMAL ELECTRICITY.
72
they
are
be
to
considered
and anodic
kathodic
IIL
respectively
effects
sums
algebraic
as
of
— resultant
from the predominance of one or other factor
alternating
series of
the
currents used
Further investigation
the nerve.
will,
in
to stimulate
perhaps, decide
this point.
As
regards the second question,
indeed, for no one
it
know what
saying that
zero,
it
which
this
I
get
means an
it
and
I
have
am
to me,
alteration
away from
very tired of
and
it
base-line
of
galvanometer
"answer."
to apologise for the
to say that
remarkable
uncompromising method of recording that
in
me
ought to be attended
may
case
are
be,
significant, but
of.
I
am
I
out of trouble, and
to,
that the rise or
very significant.
don't
know what
has
But
it.
am
I
told
as the
fall,
Yes,
they are
they are significant
quite aware of the fact that carbonic acid
from without always drives the zero up at
carbonic
it
ordinary galvano-
metric observations one does not attend to
that does not get
that
If
has only been by reason of
been made so prominent, and that
it
do not
I
the question by
alteration of the
a pretty obvious
is
does not answer,
alteration,
put
remarkable
the
Sometimes
means.
fails to
I
acid
first,
from within {by tetanisation)
drives the zero^ downwards, but
I
while
always
do not know what
that means.
^
By
zero,
I
mean
the position of rest of the permanently
deflected magnet, not its position of rest
passing.
when no
current
is
ANIMAL ELECTRICITY.
Postscript.
made on
— The
— LECTURE
dubious
tone
of
III.
the
J
T^
remarks
arose from the fact that the rehearsal
p. 62,
experiments carried out during the week preceding
the lecture were so unsatisfactory that
all
I
abandoned
hope of obtaining any clear demonstration of the
The
experiment.
principal
nerves persistendy said
"check," giving only a very small augmentation of
response
in
consequence of prolonged tetanisation,
so small indeed as to be liable to escape detection
on the demonstrating galvanometer, except
For
close scrutiny.
meter was put up
theatre,
meter
in
(as
circuit
shown
in
to
very
reason a recording galvano-
this
a dark room behind the lecture
with
in fig.
the
demonstrating galvano-
10),
so as to have a record
of the experiment actually made, to be put into the
witness-box at the end of the lecture.
i\s
it
turned out, however, the lecture experiment
came out with remarkable
after
distinctness
;
the response,
prolonged tetanisation (ten minutes), appeared
be about three times as great as before, and the
photographic record was subsequendy brought in as
to
a
somewhat superfluous piece of evidence.
This
which was more surprising
result,
lecturer than to
any of
his audience,
by Miss Sowton, who acted as
arose as follows
From
to
the
had been secured
lecture-assistant,
and
:
previous experiments
the possible nutritive action
made
in
order to test
upon nerve of proteids
and of carbohydrates, we had found that lactose, among
— LECTURE
ANIMAL ELECTRICITY.
74
Others,
appeared to have a considerable,
lutely certain, "nutritive" action.
therefore, without
experiments
allowed
Fk;. 33.
Fig. 34.
to
the
soak
(2478.)
(2501.)
my
day
in
not abso-
knowledge, made tetanisation
before
saline
lecture
solution
typical
of
upon
nerves
lactose,
and
on an ''unfed" nerve.
Effect of 10 minutes' tetanisation
effects
were considerably augmented.
The
on a " fed
in
" nerve.
such nerves
lecture
ment had been made upon a lactosed
like
if
Miss Sowton had,
Effect of 5 minutes' tetanisation
had found that the
III.
experi-
nerve,
and,
the experiments of the previous day, contrasts
very markedly with the other rehearsal experiments
made
at this period
on
" unfed " nerves.
ANIMAL ELECTRICITY. —LECTURE
III.
75
REFERENCES.
A
account of the subject of this lecture is given in Pliil
Trans, of the Royal Society for 1897 (Observations on
full
Dioxide.
with Particular Reference to Carbon
Croonian Lecture for 1896).
"
"
Nerve
Isolated
The
Staircase
;
phenomenon,
first
pointed out by Bowditch
and by Romanes
Medusa, is cona general
from
length
some
as being characteristic of heart-muscle,
as occurring in the contractile tissue of
sidered
by Romanes
standpoint in
at
and
Jelly-Fish
Star-Fish,
International
Scientific Series, p. 54.
The
notion of
"
canalisation
"
or "
Bahnung
"
is
developed
by Herbert Spencer in the Principles of Psychology, and
alluded to by Romanes (loc. cit., p. 87), who gives
references to earlier statements in a similar sense by
Lamarck
76
LECTURE
IV.
CONTENTS.
Polar
effects.
Pfliiger's
law.
by experiments on
Illustrated
Man.
Electrolytic dissociation.
Electrolytic counter-current.
Internal polarisation.
Polarisable core-models.
Extra-polar currents in core-models.
mammalian
Extra-polar currents in frog's nerve and in
Polar
effects.
— In
studying the
manifested by living matter,
we
nerve.
electrical
effects
shall repeatedly
occasion to employ electrical stimuli.
have
important
It is
at the outset to avoid a perhaps natural confusion of
ideas,
and
to expressly distinguish
applied from without by
nate as
tricity
leading-in
arising
animal or
or
within
tissue,
way
between
what we
of
or
aroused
and conducted
within
to the
way
electricity,
and
the fornier
is
the
of what
not,
elec-
living
galvanometer
The
designate as leading-out electrodes.
animal
shall desig-
exciting electrodes,
or other electrical indicator by
is
electricity
we
shall
latter alone
although
it
is
often used to arouse within living matter that chemico-
physical action of which the deflection of a galvano-
meter
is
an outward and visible
sign.
ANIMAL ELECTRICITY.
This
is,
to
some
inasmuch as the
former
title
of these lectures
title
is
But seeing that we
Strictly speaking, the
categories
— being
trical
currents;
and that we
mechanical
ordinary
very shortly have
responses
electrical
between such
relation
shall
phenomena which belong
both
shall
have
convenient
The
if
we
and
responses
necessary,
but
elec-
examine
to
significant
of
is
not merely
logically
defensible,
are to be restricted to animal electricity.
polar reactions of living matter are, as regards
physico-chemical
their
mechanism,
of
nature as those of inert matter, but in
the
to
to
responses and
electrical
physiological excitation, the digression
even
Animal Elec-
covers only the electrical effects derived
to deal with polarisation
the
"]"]
animals, not the effects of electricity applied to
animals.
the
IV.
extent, a preliminary digression
not Electro-physiology.
tricity,
from
LECTURE
former exhibit
characteristic
of
features
the
must recognise that
that are
living
state.
same
the
many
respects
peculiar,
And
electrolytic disruption,
while
and
we
whether of
living, or of dead, or of inert matter, is of .one nature
in
its
essentials,
we must
correspondence with varying
diminished
chemical
recognise
also
stability,
conditions
varying
of
that,
in
greatly
degrees
of
greatly increased polarisability will be found in living
as
compared with dead matter.
lectures
I
shall
of living matter
show
is
modifications that
In the course of these
that the electrolytic polarisation
extraordinarily sensitive to chemical
may
certainly be
termed
slight, that,
e.g.,
LECTURE
ANIMAL ELECTRICITY.
78
IV.
the electrolytic changes within a nerve are modi-
by
fied
poison
and by sedative drugs, and that a
irritant
that
reagent
a
standpoint,
protoplasm
kills
is,
from
our
immobilises
that
the
present
living
electrolyte.
The
polar
questions arising in the consideration of the
reactions
of nerve are partly electro-physical,
partly electro-physiological,
partly physiological,
in
this
respect
last
distinctly
province of purely animal
and
overlap the narrower
electricity.
Without, then, entering into details such as would
be required under the heading of electro-physiology,
and considering merely the general features of
excitation
trical
reactions
and
their
these are
actions,
so
in
far
as they involve electrical
relations
the
elec-
main
to
physiological
points
to
be
re-
insisted
upon.
down by du Bois-Reymond that
nerve is excited by a constant current, when that
"
current begins and ends, i.e., at " make " and " break
but not while it flows, i.e., between the make and
has been laid
It
—
break
It
effects.
was thereupon further proved by
(i)
That the "make"
Pfliiger
excitation
arises
at
the
excitation
arises
at
the
kathode.
(2)
That the
"break"
anode.
(3)
That during the passage of the constant current
excitability
Is
raised at
and near the kathode.
ELECTRICITY.
.-\NIMAL
— LECTURE
79
That during the passage of the constant current
{4)
excitability
is
depressed at and near the anode.
These four
nerve, express
particularly
propositions,
specially
a very general
exception
in
case
the
applicable
to
and cover more
law,
the case of muscle
as of ordinary muscle.
well
IV..
— of
heart-muscle
Subject
a
to
as
possible
of non-fibrillated protoplasm,
they express the law of response of living matter to
electrical currents.
have been
I
some
at
loss
how most
briefly
to
present to you an experimental illustration of these
two pairs of
The obvious and orthodox
principles.
object of experiment, a nerve-muscle preparation of a
not serve the whole purpose
frog, will
would do well enouq"h
to exhibit
and diminished anodic
direct
while
for,
it
auo-mented kathodic
excitability,
would afford no
it
and evident proof of kathodic make excitation
and of anodic break
I
—
excitation.
shall, therefore,
have recourse
and, in one particular,
to a less orthodox,
more complicated
object, viz., a
nerve-muscle preparation of a man, selecting for the
purpose the ulnar nerve of
muscles to which
it
is
my own
distributed
forearm and the
— these
are,
amono'
others, several of the flexor muscles of the wrist
and
fingers.
Experiment.
tery
I
have connected myself with a bat-
by means of a large
the neck
its
—
;
flat
electrode at the back of
with the knob of the other electrode held by
insulating handle in
my
right hand,
I
feel
about for
LECTURE
ANIMAL ELECTRICITY.
8o
IV.
the ulnar nerve at the back of the elbow
knob
felt
is
kathode at that
its
gradually increased, the effect of
its
A
being- tested for occasionally.
spot,
is
make and break
strength
is
reached
which each make of the current gives a sharp flexor
movement
of wrist
make,
at
cites
and
fingers
i.e.,
the current
—
you hear
but, as
you
is
made
see,
strength.
break
The
effect
—
is
changed
to
an
without producing any effect
But neither does
low current-
at least at this rather
current must be increased before any
appears with the anode over the nerve,
and then there
is
also a
make
effect
contradicts the statement that the
at
is
as before at the key, as
the anode does not excite at make.
excite at break
excitation
reversed, so that the
is
kathode pressed down on the nerve
anode, and the current
the kathode ex-
make
otherwise, the
or,
Now
kathodic.
it
the
be comfortably applied, the current,
to
directed so as to have
at
when
;
— which apparently
anode does not excite
make — that on the contrary it quells excitation.
The contradiction is apparent and not real, yet, as
regards the course of our main channel of thought,
any
full
astray.
consideration
Let
me
then
of
point would
the
us
say rapidly that in this em-
bedded nerve, current, having a
(=
lead
fairly
narrow way
in
anode), just under the electrode, has also a com-
way out (= kathode) into the surrounding tissues, at some little distance from the actual
The make effect is due to this extra-polar
electrode.
paratively broad
kathode
—please do not
regard
it
further
;
it is
a com-
ANIMAL ELECTRICITY.
LECTURE
plication clue to the fact that the nerve
but embedded.
at break,
which contraction
due
is
nerve just under the anode, and
that the
anode excites
contraction
make and
mented by
to excitation of the
that the
i.e.,
the
the
—
anode
double
break
at
—
statement
at the kathode, decreased at the
And
to be demonstrated.
way
to
do
which
through the
is
made anodic
the electrode
will
be supple-
that
during the
by a
increased
is
—which
is
easily
the clearest and least ob-
be by an apparently
by
viz.,
medium
light
of the
blows to the
electrode
or kathodic at pleasure.
somewhat
regularly tapped
anode
this will
very clumsy proceeding,
nerve,
break
kathode excites
that the
passage of a constant current, excitability
jectionable
you
anodic.
is
These two statements
at
a contraction
is
let that signify for
at break,
carefully
itself,
Pressino-
upon the nerve,
light mallet, just
it
hard enough
give distinct twitches of the hand and fingers.
is
to
While
the taps and twitches are proceeding regularly, a key
is
closed,
rendering the electrode kathodic, and the
twitches are evidently
more pronounced, whereas with
reversed current
abolished.
and an anodic electrode they are
This double experiment of which the
—
principal virtues are that
chanical,
i.e.,
normal nerve
it
non-electrical,
is
employed
is
simple,
stimulation
—
is
and that meof perfectly
good and
sufficient
evidence of the double statement that excitability is
increased under kathodic influence and diminished
6
I
not isolated,
is
Notice only that there
8
IV.
LECTURE
ANIMAL ELECTRICITY.
82
under anodic influence.
experiment
andum
(fig.
of the
35)
fact.
Here
that
will
Anodic diminution of
WW
desire further
is
the
wmmmMm
During K.
After.
excitability.
—Influence of a polarising current
nerve.
settlement,
tion
memor-
After.
Kathodic augmentation of
from
a
excitability.
vfW
iiefore.
Fig. 35.
as
and complications of
During A.
Before.
human
serve
very domestic-looking experiment
this
1-14-lW
the record of an
is
Anyone who may
acquaintance with the doubts
which
IV.
upon the electrical excitability of
(From Waller and de Watteville, Pk?7. Trans. R. S., 1882),
may
which
it
refer to the literature of the subject,
may be
gathered
that
a
verifica-
on human nerve of Pfluger's universally-admitted
principles re isolated frog's nerves
was by no means a
matter of course, but had to be cleared before
clearly visible.
it
was
ANIMAL ELECTRICITY.
It
not
is
is
law of response
this
form part of a future course of
necessary, in order to
between the
only to
warn you
mobility
"
in
is,
avoided
is
in
Erregbarkeit and
new
root
"
ability
attributes
English, subject
— that
me
that
adopt
to
if
term
the
the terms
" zinc" as
substantive "zinc-
its
of being
now,
and that one
Leistungsfahigkeit,
capability
relation
an ambiguity
to
German by
the richer
word has been
[i.e.,
it
and "electro-
that "excitability"
of the several reasons leading
a
you the
should allude to them
I
But
lectures.
clear to
that
;
and the electro-mobility of
are not parallel
excitability
that
make
excitability
matter, that
living-
83
IV.
purpose to enter into any
present
examination of
detailed
will
my
LECTURE
aroused to action
analogous with that of the zinc of a voltaic couple)
does not naturally
wide open to ambiguity, as do
lie
terms excitability and electromobility.
the
"more
terms "greater excitability,"
may
By
the
excitable," there
be implied "more easily excited," or "capable of
greater reaction."
"more
bility,"
the terms " greater electromo-
electromobile
aroused to
easily
By
"
might be implied "more
electromotive
action,"
or
capable
of beino- aroused to oreater electromotive action.
By
able
"
it
most natural
is
it
is
used
in
these lectures
the zinc
to
understand
—and
at
zinc-
any
the sense in which the expression will be
rate
greater
"more
terms "greater zincability,"
the
— capability of
being aroused to
electromotive action, analogous
in
a voltaic couple.
That
is
with that of
the sense in
ANIMAL ELECTRICITY.
84
" zincable "
which the term
the
legend
of
this
intended to serve
LECTURE
to
is
diagram
as
by the action of the galvanic
which
is
(fig.
36),
to
the polar
current.
Kathode
Aiwdt
Fig.
"Excitability''
36.
and
''
Zincability"
Less zincative.
More
More
More
Less zincable.
Less excitable.
may
in
and of electromobility effected
alterations of excitability
We
be understood
memorandum
a
IV.
zincable.
excitable.
zincative.
tentatively proceed a step further in the
and
direction of general expression,
the grey axis
is
—admitting
that
the essential part of a nerve-fibre
recognise as a possible series of associated facts
(i)
the
kathodic
the liberation
excitation
of the
grey axis
of electro-positive elements
reduction of deoxydisable " inogen
"
(?
;
;
(3)
:
(2)
the
carbohydrate)
;
(4) the evolution of carbonic acid.
The
point mentioned on
confirmatory of this view.
p. 74, is in
The
some measure
sugar appears in this
case to have played the part of an oxygen-giving food,
ANIMAL ELECTRICITY. —LECTURE
and
it
85
IV.
conceivable that by the reducing action of
is
Hving matter upon sugar, a deposit of
might be
fat
effected.
There would
thought seem to be very
at first
little
continuity of ideas between the experiments
we have
am now
turning.
just witnessed
and those
In point of fact there
is
of simple
which we are about
cules,
admit us
them
;
chemical mole-
touch upon,
is
in
that will one
all
day
deeper comprehension of the manifold
to the
and
disruptions
to
phenomenon
the key
probability
I
a close relation between
electrolytic disruption
the
which
to
complex chemical
reunions of the
molecules that compose living matter.
It is
a
step in that direction to
first
ourselves that the
phenomena
and
above
inhibition are
(that
is,
same
of polar and electrolytic
It will
be a further
direction to recognise that electro-
movements, which stand out with comparative
clearness
excitatory
that
clear to
of electrical excitation
of chemical) mechanism.
step in the
lytic
all
make
we
amid
from
phenomena
are at
loQfical
—are
conditions,
— with
such
sight tempted to
first
logical character
unexplained
the
and
jungle
clearness
deny
of
indeed
their physio-
nevertheless subject to physioat the
same time
accessible to
chemical modifications.
But
I
shall not apply
visionary castle
grovel
—
it
is
my
myself
;
I
allude
a
purpose rather to diligently
among phenomena
fundamental
to the building of
more
that are
elementary and
especially to electrotonic
86
ANIMAL ELECTRICITY.
currents,
which underlie the electrotonic alterations of
touched upon
excitability
LECTURE
previous paragraph,
in the
and which are undoubtedly the
IV.
effects of electrolytic
polarisation.
Preliminary
Experiment.
— The
two
platinum
electrodes of a battery of two or three volts dip into
a rectangular glass vessel containing a mixed solution
Fig. 37.
The
of dextrine and potassium iodide.
the potassium iodide
is
composed of a
molecule of
basic moiety
potassium, and an acidic moiety iodine, and the latter
as soon as
it
is
set free
by the
of the molecule, will signify
a red colour with dextrine.
in
electrolytic disruption
its
presence by striking
[I
have taken dextrine
preference to starch because
iodine
with starch, and to most of us there
of thouo-ht
base.]
The
between redness and
circuit
is
you see that the anode
now
is
is
acid,
strikes
blue
an association
blueness and
completed, and at once
becoming surrounded by a
red halo, indicative of the presence of free iodine, the
ANIMAL ELECTRICITY.
acidic moiety of the
molecule
appear
al the
may
take
signifying to us
electro-
:
Anode
at the
Kathode
acid
base
oxygen
chlorine
hydrogen
sodium
electro-negative ions
electro-positive ions.
These
tively
We
I.
Sy
IV.
and consequent
that with passage of current
lysis there
K
memorandum experiment
our
this as
LECTURE
electrolytic products at the
are themselves, so long
two poles respec-
as they are in statu
electromotive against the current that pro-
nascendi,
duces them
;
thus oxygen, produced at the anode, and
hydrogen, produced at the kathode, constitute a voltaic
couple
current
of which
by
the
which
current
they
are
obstructs
the original
giving
generated,
a
secondary or polarisation counter-current that amounts
virtually to a resistance against the original current.
A
voltaic cell in action, like living matter in action,
surrounds
itself
with products of
And
obstructive of that activity.
might be
and reintegration of
But
activity,
polarisation
and
and the disintegration
living matter,
not very far-fetched nor
all
cell,
own
the analogy that
drawn up between the
depolarisation of a voltaic
are
its
would perhaps be
much more
inaccurate than
analogies.
let
me
formally exhibit to you this fundamental
fact of the polarisation
counter-current.
deed already exhibited
itself
[It
informally in a
has
way
in-
that
ANIMAL ELECTRICITY.
88
is
rather
only at the anode
;
IV.
During the passage of the
instructive.
original current the
LECTURE
reddening of the
but
now
i.e.
occurred
fluid
moments
a few
after
the original current has been cut out, and only the
counter-current has been in play
reddening of the
wire,
fluid
— there
is
also a slight
round the other wire
;
this
which was kathode or way-out from liquid as
regards the original current,
is
now anode
or way-in
to liquid as regards the counter-current.]
Experiment.
— Beginning with K^ closed
©) and K^
the battery
key
the galvanometer
open,
K.^,
to
I
first
(to cut
out
open and shut
see that there
is
no
Fig. 37
current
from the as yet unpolarised wires
polarisation
Leaving K3 closed
cell.
in
the
(to protect the
galvanometer from the comparatively large battery
current
about
through the
meter
as
electrodes
I
to
cell
shown
for
a
be
used,
and
which
will
be
and would be through the galvanoby
the
arrows)
I
moment by opening
polarise
K^.
switch off the battery by closing Kj, and
the
Finally,
switch
LECTURE
ANIMAL ELECTRICITY.
in
galvanometer by opening K.
the
89
IV.
the galvano-
;
meter indicates current against the direction of the
from the now polarised electrodes.
arising
arrows,
The key K^
with which
these
open throughout
remained
the
connected has
are
The
experiment.
electrodes have been so to say charged at K, from the
and discharged
battery,
may have
meter, and, as you
and has diminished with
polarisation,
magnitude
noticed, the
increased with the duration of
has
of the deflection
K. through the galvano-
at
the
interval
between closure of K^ and opening of K3
i.e.,
with
the time during which depolarisation has proceeded.
We
seem
to
be a long way off from the case of a
living nerve, yet the distance
that of the polarisation cell
Two more
gap
the
experiments
— or
at
electrolysis that
is
at the
is
Of
seems.
think, suffice to bridge
serve
of
it
and
as
stepping-stones
phenomena
— from
the
purely physical to the electrolysis
— from
the dis-
matter to the disruption of living
:
these two experiments one
trate the fact
—
first
that the interface
may be
I
same time physiological
ruption of inert
matter
to
two orders
between the
that
least
this case
not so great as
is
will,
between
is
established by du
between
intended to
Bois-Reymond
different moist electrolytes
the seat of electrolytic polarisation
to illustrate the physical
illus-
mechanism of the
;
the other
electrotonic
or extrapolar currents to which such polarisation gives
rise.
ANIMAL ELECTRICITY.
90
In illustration of the
LECTURE
first
IV.
of these two points
I
cannot do better than show you an extremely simple
experiment that suggested
itself
only two or three
days ago as a possible lecture demonstration, and
of which nevertheless
it
does not
never tried
an
fail.
I
already venture to say that
only
I
wonder how
is
it
that
I
it
before,
for
I
have frequently wanted
illustration
of the
kind,
and wondered whether
the living tissues of the
human body
traversed by a
Counter- Current
Current
<
— Plan of apparatus for the demonstration of " internal
>
Fig. 38.
of the
human
'
polarisation
subject.
galvanic current give rise to any demonstrable internal
polarisation,
too well
or whether
washed by the
they are so to speak kept
alkaline blood traversing their
capillaries.
Experiment.
R
and
L
— Here are two
vessels of salt solution
connected with the two poles of a battery.
Here are two other
vessels R'
and L' of
connected with a galvanometer, which
is
salt solution
shunted to
such an extent that on completing circuit through
my
LECTURE
ANniAL ELECTRICITY.
any
finger into each vessel,
body by dipping a
9I
IV.
acci-
dental inequality on the two sides does not affect the
Such being the case
instrument.
polarise myself for
I
an instant by dipping a pair of fingers into the battery
vessels
R
L,
fingers
to
the galvanometer vessels,
you
is
and quickly
transfer the
external, at the way-in
in
which
it
exists.
proper
—
it
merely serves
meter
That
left.
show the
to
direction
to expect the effect of internal polarisation
To
I
end
this
—and
this
make
same way
the
in
R
and
sure of the effect
;
L,
but
then
I
into the galvano-
possibly polarised tissues
by dipping another pah' of fingers
circuit
if
the experiment
is
myself again
polarise
for a little longfer to
my
and as
L'
and way-out of current between
through the same fingers dipped into
put
pair of
may be wholly
a mixed effect of polarisation that
;
R'
sharply deflected to the
see, the spot is
skin and fluid
same
into
the vessels R' L', thus avoiding the external polarisation of the
There
pair of fingers.
first
now
is
a
considerable deflection, not quite so sharp as before,
but
in
the
polarisation
same
the
at
skin,
without
and
significant of internal
skin.
Finally
experiment with reversed direction of
current, a reversed effect
this
independent of external
the tissues below the
polarisation in
repeating the
direction,
fail
it
is
is
obtained.
necessary to
for a rather longer time in order to
let
But
to
show
the current flow
wipe out the
effect
of the previous polarisation.
I
shall
not
now
enter into any details as to the
ANIMAL ELECTRICITY.
92
LECTURE
may
possible seat of this effect, which
at
many
sorts of interfaces
IV.
obviously arise
between the various
tissues
traversed by the current, but give the experiment as
an internal polarisability of
stands, in evidence of
tissues taken en bloc.
Obviously
it
living-
gives no specific
it
information as regards the polarisability of any one
particular tissue.
The second
of our two stepping-stones towards
the case of nerve
is
a purely physical experiment
indirectly demonstrative of a peculiar distribution of
JUUIUIUUI
-S
current,
— z-^/ A—^K
4-^3
Fig. 39.
— " Anelectrotonic
by
effected
nerve, which
is
" current
one
which polarisation
tissues in
and characteristic of
polarisation,
just the
from a core-model.
among
tissue
is
most
all
other
easily produced,
yet most difficult to directly demonstrate by reason of
its
extreme evanescence.
by which
to
living nerve.
fact
the
I
know
of no direct
means
demonstrate an internal polarisation of
The
peculiar
chief evidence of polarisation
extrapolar
distribution
of
ness upon
a polarisable
platinum wire surrounded
sulphate.
we
in
current
along a nerve, termed an electrotonic current, and
a similar extrapolar current that
is
it is
are about to wit-
core-model consisting of a
by a
fluid
sheath of zinc
LECTURE
ANIMAL ELECTRICITY.
Experiment,
[fig.
39]
is
from
— The
A to
original
93
IV.
or polarising current
K. In consequence of
electrolysis
entrance and exit between liquid
at the surfaces of
sheath and metal core, counter-current
is
aroused, acting
and
as a resistance, causing the surfaces of entrance
to spread
along the model.
In the figure
exit
you must
imagine that the anodic or electropositive state shades
that
I
and
then
2,
Fig. 40.
o"et
2
and
3,
then 3 and
value, so
vanometer from
2 to
I,
3 to
Precisely
4,
you
will
— " Katelectrotonic " current from a core-model.
three diminishingr values for
from
minimum
to a
you connect a galvanometer with extrapolar
if
points
maximum
from a
off to the left
i
to
2,
current in the
2 to 3, 3 to
2,
4 to
4
(in
oral-
the wire core
3).
similar effects
would
be
observed on
connecting the galvanometer with a series of points
on the side of the kathode to the right of the polarising current
in
fig.
40.
But
it
will
obviously be
simpler to reverse the poles of the polarising battery,
giving
all
currents with arrows
instead of to the right.
pointing to
the
left
ANIMAL ELECTRICITY.
94
These
anode
fig.
40,
in
extrapolar
fig,
imitate
the
siologists as
of the
And
kathode
what are known
Anelectrotonic and
currents of nerve.
IV.
on the side of the
currents,
on the side
39,
precisely
LECTURE
it
is
in
phy-
to
Katelectrotonic
highly probable that
the latter like the former are of electrolytic origin.^
But now as regards any possible future
tion of ionic products in nerve,
guard.
At
then leaves
at
we must be on our
the anode the current
it
to enter the
the interface between
kathodic or basic.
identifica-
enters the fluid,
metal core
;
the ions arising
sheath and core are
Similarly
the
ions
of the
thus
fluid
sheath round the core under the battery kathode, are
not kathodic, but anodic or acidic.
This point
will
come up again
in
the case of
medullated nerve-fibres, where core as well as sheath
is
a moist non-metallic electrolyte.
Meanwhile,
to-
wards the avoidance of a confusion not seldom made
here between anode and kathode, way-in and way-out,
I
give a formal experiment on a core-model,
in
which
^
Similar experiments can be made on core-models without
any central wire, on e.g. a clay pipe soaked in salt solution and
du Bois-Reymond infilled with a solution of copper sulphate
deed showed long since that the surface of separation between
two different electrolytes traversed by a current, gives birth to
electrolysis (hydrogen and base in the electrolyte behind the
Monatsber.
current, oxygen and acid at the electrolyte in front).
d.Berl. A kad., I y. ]u\i, 18^6. Gesammelte Abhandlungen. Ueber
Polarisation an der Grenze ungleichartiger Elektrolyte, vol. i.,
;
p. I.
— LECTURE
ANIMAL ELECTRICITY.
the anodic surfaces will be
tig.
at
41,
the
and
4,
I
In the
character.
acidic
battery
anode
fluid
to
to fluid
is
95
by
visible to us
experiment
electrodes
fluid
at
platinum)
(of
2
at
and
i,
3.
Taken
at
2,
The
4.
i
and
41.— Experiment
3,
and you
will
illustrating the entrance
The
latter
not
and
fail
to
4.
remark
exit of current to
current in the direction
i and 3, leaves the fluid at 2 and
and 4 are " kathodic " as regards the fluid.
enters the fluid at
the
effect of
apparent as a reddening at the
is
the sheath and axis of a core-model.
at
at
fluid
fluid
we
a mixture of dextrine and potassium iodide,
two surfaces
that
are
order
in
kathode from
kathode from
3,
anodic electrolysis
2
by
illustrated
soon after closure of the battery current the
Fig.
their
the electrodes between fluid sheath and
platinum core are at
have anode
made
l\.
i
and from
i, 2, 3, 4,
and 3 are thus "anodic,"
of these the effect
is
most pro-
nounced immediately under the battery kathode, but
shades off in diminishing degree
to
a
considerable
distance along the wire in an extrapolar direction.
The
core-model used
in
the experiment of
p. 92,
ANIMAL ELECTRICITY.
96
LECTURE
consisted of a platinum wire in
and
sulphate,
difference of
in
case
that
IV.
a solution
there
of zinc
was no marked
magnitude between the anodic and the
kathodic extrapolar currents.
Here
is
another core-model, composed of a zinc
wire in a solution of sodium chloride
On
the effects are unequal.
OT
;
in
this
case
closure of the polarising
volt
0-3
0-6
=
—
Fig. 42 {2369).
Extra-polar (
"electrotonic") currents of frog's nerve,
At
produced by polarising currents of increasing strength, from 0"i to 0*6 volt.
each strength the A. and K. currents are taken twice. Their magnitude may be
approximately estimated by reference to the standard deflection of O'OOi volt re-
corded
at the
commencement
of the observation.
current in one direction (to the right), there
marked anodic extrapolar current
closure
of
the
direction (to the
left),
there
extrapolar current to the
is
a
much
be the rule
in
the
On
opposite
smaller kathodic
left.
These two core-models reproduce
shall find to
a well
(to the right).
current
polarising
is
to us
in the case of the
what we
nerves of
ANIMAL ELECTRICITY.
LECTURE
IV.
97
cold-blooded and warm-blooded animals respectively,
and
I
will
bring this group of introductory considera-
tions to their conclusion
by a cursory demonstration
—^upon the nerves
kitten respectively — laying them
of this contrast
of a frog and of a
in turn
by which polarising current
of electrodes
the nerve
upon two
and extrapolar current
is
pairs
led
into
led out to
the
is
galvanometer.
With
(to
the
the frog's nerves the anodic extrapolar effect
right)
is
comparatively large, the
—
kathodic
(=
" electrotonic ") currents of kitten's nerve,
Fig. 43 (2383).
Extra-polar
produced by polarising currents of increasing strength from 0-5 to 2-0 volts. (The
standard deflection by o-ooi volt had a value of 40 mm., so that e.g. the A. and
K. currents at 2 volts have an E.M.F. of about 0-0007 volt).
extrapolar effect (to the
These extrapolar
lor
they are, as
left)
is
effects are not
you
see,
pinching the nerve between
comparatively small.
due
to current-escape,
completely abolished by
the
two pairs of
elec-
trodes.
With the
7
kitten's
nerve the anodic and kathodic
LECTURE
ANIMAL ELECTRICITY.
98
extrapolar
They
magnitude.
pinching
completely
are
between
nerve
the
and of
well-marked
are
effects
IV.
equal
by
abolished
two
the
of
pairs
electrodes.
These
nerve
of
last
experiments
in particular
my
—
of
extrapolar
currents
"physiological"
the
—
at
and
therefore,
little
to
say.
At present
it
is
it
frog's
little
know-
Isolated
mam-
" negative variation,"
was thereby deterred from taking
systematic study.
case of
have
I
fully
of these
nature
the
in
least
malian nerve gives no
frog's
to
become
then
shall
Of mammalian nerve
nerve.
relating
form the point of departure
We
next lecture.
convinced
ledge,
will
—that
and
I
as an object of
to
me
a rather
mysterious stranger.
ISote.
are
— Electrotonic
much
less
currents, according to
Biedermann,
marked on non-medullated than on medullated
nerves, the katelectrotonic current in particular being absent.
This however
is
denied by Boruttau
(Pfliiger's
Archiv,
Ixvi.,
p. 285, 1897).
The presence
nerves
is
of electrotonic currents
on non-medullated
in apparent contradiction with the view taken in
these lectures, that the interface between grey axis
sheath
place.
is
fatty
the surface at which electrol5^ic polarisation takes
But the non-medullated
non-medullated
continuously
nerves
myelinated nerves.
in the
are
myelinated,
diffusion appears to be
cance
and
more or
and
much
state is
in
less
any
not absolute,
less
many
distinctly
case
and
electrotonic
pronounced than on
There may prove to be some
fully
signifi-
relation that apparently obtains in the
com-
ANIMAL ELECTRICITY.
parative
LECTURE
IV.
99
magnitudes of anelectrotonic and katelectrotonic
effects in the different classes of nerves, viz., A.
much
greater
than K. in non-medullated nerves, A. greater than K. in
medullated nerves of cold-blooded animals, A. equal to K. in
medullated nerves of warm-blooded animals.
But
I
am
nature of the
mammalian
in
still
doubt concerning the " physiological
extrapolar A.
nerve, nor
do
I
and K. currents
yet
know whether
of " negative variation " on such nerves
is
in
of
isolated
the absence
any way con-
nected with the equality of these currents.
REFERENCES.
" Polar effects "
"
were first fully described by Pfluger in his
Untersuchungen uber die Physiologie des Electrotonus."
Berlin, 1859.
The
polar effects on Man are described by Waller and de
Watteville in the Phil. Trans. R. S. for 1882. (Influence
of Galvanic Current on the Excitability of Motor Nerves
of Man.)
Polarisable
core-models were
gated by
Hermann
first
systematically
{Pfliiger's Archiv, vols,
v.,
investivi.,
vii.,
Handbuch, vol. ii., p. 174). They have recently
been still more closely studied by Boruttau. PJluger's
1872-3.
Archiv, 1894-6.
These three topics are
duction to
Human
briefly
summarised
in
my
" Intro-
Physiology," 3rd Ed., pp. 364, ^66, 370.
Internal polarisation
first
alluded to by du
the "Thierische Elektricitat
" in
Bois-Reymond
in
1849, and again in 1883
ANIMAL ELECTRICITY.
lOO
in his
monograph
cheinungen
LECTURE
IV.
" iiber seauiddr-elektroniotoriscJie
am Muskeln, Nerven und elektrischen
Ers-
Organen.
Berliner Sitzungsberichte, 1883.
In connection with the italicised words on
sentence
is
of particular interest
warum
:
p. 91,
"
the following
Ich begreife aber
den Versuch so abanderte,
dass beispielsweise mit den Zeigefingern der Schlag
genommen, von den Mittelfingern die secundar-elektroheute nicht,
ich nicht
motorische Wirkung abgeleitet wurde." (Loc.
cit., p.
371).
lOI
LECTURE
V.
ELECTROTONUS.
" An." and " Kat."
Physiological
Influence
and physical
currents
Fleischl's
and
ether
The
chloroform.
electro-mobility
Relation between polarising and extra-
of living matter.
polar
of
effects.
in
Strength.
nerve.
deflection.
Action currents
Von
Distance.
are counter
-
cur-
Extrapolar effects in mammalian nerve.
rents.
To-day's chief experiment presents to you a demonstration of
du Bois-Reymond's electrotonic currents,
commonly
referred to by physiologists as Anelectro-
tonus and
Katelectrotonus, but
which
shall
often
take the liberty of calling by the shorter and
more
familiar
the
still
workshop names of An. and
upon two
(Fig.
44.)
The nerve
p p'
to give off
ing circuit
to
is
resting
the polarising current from a battery (in
through
e e'
is
i
'5
volt),
and
the electrotonic current which
be indicated by the galvanometer.
made
and by
pairs of unpolarisable electrodes, to receive
the present instance at the pressure of
will
Kat.,
shorter pen-names A. and K.
Experintent.
through
I
completed at
pass in one or
will
The
polaris-
by the key, and
the other
direction in
it
is
the
nerve by means of a reverser, rev.^ parallel with the
transparent scale of the galvanometer.
^ For
prolonged experiments a revolving key is used, by
which the polarising current is made through the nerve at
regular intervals in opposite directions.
ANIMAL ELECTRICITY.
I02
The
nerve
such that
the
direction
the
represents
nerve.
facing you
is
Closing the key,
p'
deflection
to
your
from e to
ElG. 44.
the
nerve.
which
the
spot
through
current
the
I
make
a polarising cur-
;
there
is
a considerable
the nerve in the
in
moves
indicating the presence
right,
an extrapolar current
and the connections are
of
direction
rent in the direction p
tion
in
;
LECTURE Y
same
of
direc-
or towards the polarised region of
e',
— Diagram of
This
is
experiment to demonstrate A. and K.
an Anelectrotonic current, so-
on the Anodic side of p p'.
Turning over the reverser to the left, and again
called because
is
it
closing the key,
I
make
opposite direction p' p
pronounced deflection
the polarising current in the
;
to
there
your
is
left,
presence of an extrapolar current
now
a rather less
that indicates the
in the
nerve to your
ANIMAL ELECTRICITY.
from
left,
This
it
e' to
<?,
LECTURE
or from the polarised region p'
on the Kathodic side of
You have now
trials
p.
a Katelectrotonic current, so called because
is
is
103
V.
rapid
in
seen
p' p.
—and
I
will
repeat the two
in
each case the
— that
succession
extrapolar or electrotonic current, whether A. or K.,
passes in the nerve in the
by which
ising current
Your
I
first
ment.
story,
a
repeated
it is
aroused.
perhaps
is
Is that all
which you
?
Yes, that
is
the gist of the whole
will find set forth at great
long series of memoirs
—
direction as the polar-
—as was mine when
the experiment —
one of disappoint-
thought,
first
same
length in
extending over the
last
at such length indeed that without
some
definite assurance of the simplicity of the facts,
even
fifty
years
a careful reader might pass
point altogether, or as
by, either missing the
it
was the case
text-book a few years ago, confusing
sarily with
fusion
mind
it
quite unneces-
at the
very out-
work, but the confusion that remained in
for at
preserved
every English
Indeed, this con-
was made by du Bois himself
set of his
his
the current of injury.
in
in
most a few months, was scrupulously
the
text-books
upwards
for
of
fifty
Why
this
years.
Your next thought
is
is
one of suspicion.
mere current-diffusion along a conductor,
just like
what would happen along a hank of wet wool.
is
a perfectly reasonable thought
diffusion
might well take place
;
;
it is
That
ordinary current-
indeed a
common
ANIMAL ELECTRICITY.
I04
fallacy
we must
;
exclude
— LECTURE
V.
observe
in the first place
care to
all
and then we must take means of assuring
it,
ourselves that
has been excluded.
it
But even before
this
is
done you
have noticed
will
a point that hints at something in the nerve other than
The A.
ordinary current-diffusion.
K. deflection are unequal
— A.
and the
deflection
greater than K.
is
If
the two deflections had been by current-escape they
would have been
This
does
equal.
indeed
not
current-escape,
for
the
exclude
may be
latter
the peculiar something else that
to us.
So we
use
shall
all
is
present with
becoming apparent
means
further
thought of
the
try
to
point.
Let us anaesthetise the nerve by a
chloroform vapour, that
will
little
ether or
presumably distinguish
between a "physiological" and a "purely physical"
factor in the
physical.
phenomenon, which
That which
is
in toto
is,
of course,
" e.^,,
"physiological
depen-
dent on the physico-chemical conditions peculiar to
the
living
purely
be suppressed
state will
physical,
dependent
i.e.,
that which
;
on
the
is
physical
properties of the dead nerve will persist.
Ether, Chloroform.
experiments
in
which
from which you
may
— Here,
then,
this test
has been applied, and
recognise the propriety of dis-
tinguishing two factors in the entire
physiological factor,
anaesthetic
influence
are a couple of
phenomenon
true An. and Kat., subject
—a
purely physical
factor,
—
to
the
ANIMAL ELECTRICITY.
Fig. 45.
f
1
n
[
!
i
•
f
LECTURE
IQ:
V.
— Effect of ether on the anelectrotonic current.
'fi
f
'
M
^
'
'
'
»
i/J
:\
m)
Fig. 46.
— Eflect of
chloroform on the anelectrotonic current.
»
,
!
i
ANIMAL ELECTRICITY.
I06
"physicaP electrotonus
"
of
LECTURE
V.
German monographs, not
we shall designate
suppressed by anaesthetics, which
by the colourless and non-committal expression "residual deflection."
This residual deflection
in fig,
46
mainly
I
—
itself
think,
—particularly well
marked
gradually declines in course of time,
by reason of the drying, and therefore
increasing resistance, that you recollect to be one of
the effects produced by anaesthetics.
detail
upon which we need not
connection
obvious
is
it
But
this
and
dwell,
in
is
a
this
hardly necessary to insist upon the
fact that in this case, as in that of the neo-a-
tive variation, chloroform exercises a
and ether a temporary
permanent
effect
effect.
There are other signs by which we can recognise
that the extrapolar currents. An.
How much
and Kat., although
Hering, and
sometimes turns upon a word
Biedermann, speak of "physiological" and
"physical" electrotonus, and by physical electrotonus I for a
long time supposed that they meant to designate a phenomenon
intermediate between the physiological effect proper to living
nerve and physical current-diffusion an electrotonus in fact
proper to dead, but otherwise anatomically perfect nerve. And
in this belief, although explicitly stating that in my hands
anaesthetics had served to distinguish between electrotonus and
^
!
his chief Heutenant,
—
current-escape,
I
nearly succeeded in persuading myself of the
existence of a physical electrotonus distinct from current-escape.
Hering, however, has since informed me that " physical electro-
tonus " arose as a laboratory term meaning neither more nor
less
than current-escape.
LECTURE
ANIMAL ELECTRICITY.
in last resort physical, and, as
shall see, of electro-
nevertheless, entitled to the rather
are,
origin,
lytic
we
IO7
V.
indefinite qualification "physiological."
Interrupt the physiological continuity of the nerve
between the leading-in and leading-out electrodes, by
crushing
the interpolar region
in
it
by touching
better
44),
used), but the extrapolar effects
if
or
The
the physical
abolished,
is
enhanced
intact (or
is
(fig.
p
with a drop of strong acid.
conductivity
physiological
conductivity
it
e'
acid has been
A. and K. are com-
pletely abolished.
Raise the temperature of the nerve above
lower
it
to say
—the
least
—
5°,
and although
—
in
the
40°, or
case at
first
physical conductivity has been enhanced,
the extrapolar currents, A. and K. are abolished, either
temporarily or permanently.
There
properly
is
made temperature
fig. 6T)
(and
me
that
to
tious
hot
no time to-day
trial
it is
only as
me
to
show you a
observation, as given in
am
I
for
speaking that
we might have made a rough and
by merely dropping the nerve
salt solution),
but
I
occurs
it
expedi-
some
into
can at once show proof that
the A. and K. effects you have just witnessed did not
depend
upon current-escape.
with
forceps,
that
they are
Pinching
and then testing as before,
completely
deflection whatever,
i.e.,
abolished.
nerve
the
we
There
is
find
no
no current-escape.
These currents depend therefore upon the physiological state of the
nerve
— upon
its
"vitality"
—and
I
ANIMAL ELECTRICITY. — LECTURE
I08
may
vary with variations
add,
that
in
nerves give bad currents, and that
case at this
season
of the
V.
Bad
state.
specially the
is
when
year
(February)
little
doubt that these
nerves are at their worst.
There can
extrapolar
be,
think,
I
currents
an
are
effect
This interpretation,
polarisation.
by Matteucci, elaborated
ated
of
electrolytic
which was origin-
Hermann,
by
and
more recently by Boruttau, has completely displaced
who
the original interpretation of du Bois-Reymond,
discovered the facts
I
think
consideration could only complicate the question
its
to us
it
—so completely indeed that
;
if
you are curious
argued
vol.
ii.,
at length in the
will find
" Thierische Elektricitat,"
289 to 389.
p.
Nerve,
electrolyte,
fibre
you
in the matter,
made up
or
medullated
of
fibres,
is
Each
a pair of electrolytes.
rather
an
consists essentially of a central grey core sur-
rounded by a sheath of white matter.
composed of such
the fact that nerve
only^ tissue of the
currents just
electrolytic
And
fibres
from
is
the
body that exhibits the extrapolar
we may conclude
described,
interface
is
that the
the surface of separation be-
tween grey axis and white sheath.
The
electrolytic
effects
are
as
follows
:
current
entering the nerve by the anode, traverses the white
sheath
'
to
the
grey core
;
at
the interface
between
Subject however to some reservation, as indicated in the note to Lecture IV.,
p. 98.
ANIMAL ELECTRICITY.
sheath and core
It
has
its
—^LECTURE
exit
109
V.
from sheath where
Hberates the positive ions (base, hydrogen), and
entrance
core
into
where
it
Hberates
the
it
its
neoative
Leaving the nerve by the
ions (acid, oxygen, &c,).
kathode, the current passing from grey core to white
sheath has
to
exit
its
from the core and
its
entrance
the
sheath,
and consequently positive ions are
Fig. 47.
— Diagram
illustrating the theory that extra-polar currents of medull-
ated nerve are due to electrolysis at the interface between
sheath and axis.
Following the direction of the polarising current from copper to zinc through the
nerve fibre we have
:
(i)
Anode
I
(2)
Kathode from sheath
I
(3)
Anode
to sheath
to axis
3 (4)
Kathode from
t (5)
Anode
(6)
axis
to sheath.
Kathode
to sheath
Acidic electrolysis.
Basic
,
no
ANIMAL ELECTRICITY.
added resistance
to
which a
the
at
LECTURE
The
on each side of each electrode.
and kathodic currents witnessed
physiological
"
which
to
;
is
not physiological."
as
it
I
this
physical, not
is
should reply
It
is
"
:
yes cer-
mean
that
it
physiological in so far
depends upon physiological conditions, upon the
state of
nerve that we
physico-chemical
the
in
living,
a state of peculiar
subject
to
—temperature,
influences in
to consider
call
lability,
modifying influences
all
commence-
at the
physical, but that does not
is
it
extrapolar anodic
lecture are thus accounted for.
Again you say perhaps "but
tainly
by reason of
interface,
spreading of current takes place
lona"itudinal
ment of the
V.
kinds
moisture,
we
short that
all
of
drugs,
are accustomed
terms of their unanalysed
on
effect
living matter.
Yes, the
phenomena
also physiological
unless
exclusive,
for
phenomena
;
are physical
reserve
of which
the term physiological
we
are
the physico-chemical mechanism.
mena
is
unable
The
to
venture to hope that
to express physiological
enterprise
we
a good deal
shall
detect
chief aim of
terms of physics and chemistry.
in
shall not
they are
the two terms are not mutually
we
physiological study
but
;
pheno-
And
be able to push
further in
this
be disappointed or surprised
if
direction
much
I
this
;
I
of our
study of living nerve should turn out to be a study
of the simple
if
phenomena
the depressant action
of electrolytic mobility, and
upon nerve of
anaesthetics
ANIMAL ELECTRICITY.
and
and
narcotics,
alkaloids,
prove to be a chemical
this
may be
tinct
stage to
pursue
I
do
the argument
aim of physiological endeavour
in
terms
of
the
I I
1
ultimately
of normally
however, wish
not,
necessary to convince you that
"physiological"
V.
should
&c.,
immobilisation
electro-mobile protoplasm.
at
— LECTURE
further
it
is
than
the dis-
to express
the
"physical" and
" chemical."
L.
o"i
o"ooi volt.
R.
volt
—
Extra-polar (= "electrotonic") currents of frog's nerve, proFig. 48 (2369).
duced by polarising currents of increasing strength, from O'l to o'6 volt. At each
Their magnitude may be
strength the A. and K. currents are taken twice.
approximately estimated by reference to the standard deflection of o'ooi volt
recorded at the
And
examine
nomena
commencement
it
all
of the observation.
will
be part of our immediate task to
the
accessible electro-physiological phe-
of nerve with a view to determine whether
or no they are reducible to the somewhat less mysterious
form of electro-physical and chemical phenomena.
ANIMAL ELECTRICITY.
112
LECTURE
V.
In this connection the next effects to be analysed
be those
will
Hermann,
discovered by Bernstein and by
first
the
viz.,
decrement
electrotonic
and the
polarisation increment.
But before doing
I
points
further
three
or
this
should like to take up two
relating to
the
electrotonic
currents themselves.
I
by means of a few
shall recapitulate these points
how
simple experiments, showing
the extrapolar current varies
of the
polarising current
magnitude of
with the magnitude
(i°)
and
the
with the distance
{2°)
between leading-in and leading-o.ut electrodes.
(1°)
The nerve
trodes p p' and e
is
e'
resting
as
upon two
shown
in fig.
pairs of elec-
A
44.
polar-
ising current of o*i volt gives rise to an electrotonic
deflection of
and
"5
i
;
with the polarising current at 0*2
o*3 volt, the deflection
(and perhaps
in fig. 48),
we
still
is
3
and
4-5.
better from the record reproduced
learn that the magnitude of the extra-
polar current led off at e
e'
varies
directly as
magnitude of the polarising current led
This
quite
is
From which
in
extrapolar current
in
harmony with the view
is
an electrolytic
effect,
at
p
that
the
p'.
the
and with
the fact that electrolysis varies directly with current
density.
Now
for the effect of distance
and leading-out
(2°)
2
A
between leading-in
electrodes.
nerve
is
resting upon six electrodes
;
i
and
are to remain throughout electrodes of the polar-
ANIMAL ELECTRICITY. — LECTURE
ising current,
of about
I
which
volt
'5
current by 6 and
that
5,
constant value
the
at
shall lead off
then by 5 and
I I
the extrapolar
then by 4 and
4,
3,
with distances between leading-in and
to say,
is
we
;
be
to
is
V.
leadinof-out electrodes at
q.
2
and
centimetres.
i
654321
We
begin with e
e'
at
6 and
the polarising current through
deflection
tonic
5
cm. of scale.
5
and 4
;
30 cm, of
and
3,
is
just visible
We
make
and
i
We
a second
make
a third
the electrotonic deflection
right off scale,
tion the
and
to get a
2
the electro-
;
being about
you,
to
with e
trial
the electrotonic deflection
scale.
and complete
5,
is
trial
is
larger,
with e
much
measurement of
e' at
about
e'
larger
at
4
still,
this deflec-
galvanometer would have to be shunted.
From
table, we
these data, and
see that
still
more
the magnitude
Distance between leading-in electrodes
Polarising current by
Length of nerve between leading-in and leading-out electrodes.
i
leclanche cell
(=
from
this
of an electrotonic
=
=
Distance between leading-out electrodes
clearly
cm.
i
i
cm.
i"4 to i'5 volt).
ANIMAL ELECTRICITY.
114
This
is,
in
— LECTURE
V.
the one obvious distinction between
fact,
an electrotonic current proper and a negative variation
the latter
;
independent of the distance between
is
No
leading-in and leading-out electrodes.
phenomena
an
are
expression
of
former of a stable polarisation, the
stable
as a
doubt both
of an un-
latter
and fugitive polarisation that propagates
wave along
the
present juncture
compound
it
is
electrolyte^
not necessary that
I
it
itself
but at the
;
we should
study this rather complicated question, and
reserve
the
polarisation,
I
shall
for a future occasion.
wish rather to exhibit some further definite data
concerning the polarisation phenomena of nerve
of which
cannot
I
planation,
propose any
at present
which are evidently pieces
but
—-data
final
ex-
of
that
particular puzzle.
One
is
a fact
has figured
first
by
The
their paradoxical
call
other
is
a
little
years
bunch of
me
for
the last ten years
bearing.
I
have not hitherto
have tantalised
ventured to
in
Fleischl, that
v.
in physiological literature for several
past as a sterile item.
facts that
pointed out by
attention to them, and
I
do so now
They are fragdo not know what
a very dissatisfied frame of mind.
ments, evidently significant, but
they signify,
I
I
cannot even imagine what they signify.
Boruttau hag placed the finishing touch upon the identifiphenomena in nerve and in core-models by
showing that in the latter as in the former a diphasic negative
wave is aroused by a single induction shock whatever the
^
cation between the
direction of the latter.
LECTURE
ANIMAL ELECTRICITY.
Here
is
von
V.
II5
coil
are in one
Fleischl's experiment.
maJk.^
Fig. 49.
Nerve, galvanometer, and secondary
Without the nerve in circuit
circuit.
circuiting
key down)
I
right,
if
The make
the break deflection
see, the
with a short
test for the direction of the
and the break induction currents
and galvanometer.
{i.e.,
is
to
deflection
your
make
secondary
in the
left,
is
to
coil
your
and, as you
two deflections are equal and opposite, so that
make and break
a series of rapidly alternating
currents
is
passed through the galvanometer there
But when
no deflection.
to put the nerve in circuit,
currents, there
is
is
open the nerve-key so as
I
keeping up the alternating
a deflection to your
left,
i.e.,
in the
direction of the break current.
To what
is it
is
this deflection
physiological
?
It
sation counter current
answered that
might have
it
is
;
is
in
But
I
?
Is
it
any case due
a few years ago
I
physical or
to a polari-
should have
physical, not physiological,
illustrated the
and
I
answer by reproducing the
experiment on a polarisation
all.
due
cell
without any nerve at
should have had to take stronger currents,
and with various
deflection,
now
electrolytes
physiological,
is
by
But now
it
not
that
the
fore
till
when
the nerve
is
in
traversed
As you
spot remains unmoved,
even
;
these are raised to an excessive strength
begins to
spot
which
effect
and
into hot water
considerably strengthen the induced currents
I
is
it
statement
series of alternating currents.
the galvanometer
when
answer that
I
no longer any deflection
is
the direction of the break
see,
it
in
on the electrodes), and showing that on
the dead nerve there
by the same
make, now
shall illustrate this
nerve (dipping
killing the
replacing
and
V.
might have shown
I
in the direction of the
the direction of the break.
it
LECTURE
ANIMAL ELECTRICITY.
Il6
I
shift.
This
do not understand, and
make no attempt
easy to distinguish
to
explain.
a physical
is
It
there-
shall
however
is
from the deflection afforded by
living nerve.
Well then, admitted that the deflection
direction of the break
is
the
in
"physiological," present with
the living nerve but absent from the dead nerve, and
dependent upon the polarisability of living nerve
we
are
able to proceed
analysis
I
further,
with any legitimate assurance;
Fleischl gives a highly
shall not
^
V.
our explanatory
?
Not much
V.
further in
reproduce to you.^
Fleischl's experiment
given in the
complex explanation which
"Wiener
and
Hermann
regards
his interpretation
Sitzungsberichte, 1878.
of
it
it
are
LECTURE
ANIMAL ELECTRICITY.
as a polarisation increment/
am
I
not satisfied with
either of these explanations, but think
that the
witnessed
a
is
designated as
"positive
Hermann
and
du
what
of
case
more probable
it
which you have just
Fleischl's deflection
v.
II7
V.
Bois-Reymond
Hering
and
polarisation,"
subsequently showed to be an after-
These
anodic action-current."
are the several currents,
of which on this view only the after-anodic actioncurrent
apparent to you as a deflection
is
the
in
direction of the break.
Seeing that the nerve and
galvanometer scale
facing
are
connections are such as to
you,
make
^
Hermann, Handbuch,
There
is still
direction of the
break.
may be due
after make over
Although
exceeds that by the
under
the
the nerve (you
p. 167.
a fourth possibility,
experiment,
physical
ii.,
break
polarisation current
after
vol.
the
that
deflections on the
scale signify directions of current In
'•*
and
the
that the effect in the
i.e.,
superiority of
a
to
the
the polarisation current
ordinary
by
electrolysis
a
conditions
corresponding make-current,
ceivable that the polarisability of living matter
of
break-current
it
may
is
con-
be such
may produce a greater electrolysis
than the shorter break-current.
The so-called "positive polarisation" or post-anodic action-
that the longer make-current
current, which
is
is
in the
same
direction as the exciting current,
very readily intelligible as the effect of a post-anodic zinca-
tivity.
It
is
easy to demonstrate.
Its
theoretical
part during the passage of an exciting current,
counter-
and opposed
to that current, is equally readily intelligible as the effect of
kathodic zincativity.
of direct demonstration.
It is,
as far as
I
can see, insusceptible
ANIMAL ELECTRICITY.
Il8
may
is
LECTURE
moment imagine
an enormous nerve) we have
i.e.,
indeed for the
V.
the
that
scale
:
to the rioht +
1.
The make-current
2.
Its
3.
The
4.
Its
5.
V. Fleischl's current to the left
counter-current to the
break-current to the
left
left
—
>-
^
-
^-«
—+
—
>-
counter-current to the right
-<
as an after-anodic action-current of current No.
3,
which alone
is
" zincativity "
on the side where the arrow-tail has
been figured.
post-anodic
But
it
am
the
each
four currents
or
other,
the
in
Considering
78),
3,
4
sorry to dwell so long upon this apparently
still
let
me
state in a
me up
sentences the reasoning that brought
(p.
2,
any difference
if
2.
small and dubious point,
it.
i,
should be to the right by reason of an
excess of 4 over
I
to
rise
for this arrow-tail representing a
zincativity
would neutralise
occurred
and which gives
exciting,
make
that
that excited tissue
is
excitation
is
against
kathodic
zincative (p. 84),
make and break induced
that
being equal
currents
quantity and unequal in potential,
few
will
therefore
be unequally excitant, while neutralising each other
on the galvanometer,
and galvanometer
to
one
argued that with the nerve
circuit,
it
might be possible
obtain a deflection in the direction of the
owing
In
in
I
the
to
an action-current opposed
event
I
obtained
and reproduced what
I
just
the
make
the
break.
opposite
effect,
to
recognised to
be
the effect
LECTURE
ANIMAL ELECTRICITY.
II9
V.
in
the direction of the break previously observed by
V.
Fleischl,
perfect
My
reasoning had evidently been im-
from
starting
;
no doubt theoretically
the
any exciting current should
correct assumption that
arouse an action-current of the nature of a polarisation counter-current,
it
upon nerve, and
I
sought to obtain evidence of
failed to
do
so, partly
by reason
of the fact that the excited state in nerve does not
remain localised but spreads rapidly, partly by reason
of
unknown
then
the
action-current,
after-anodic
which on the contrary appears to be a prolonged and
Direct evidence
localised state.
during the passage
of an exciting current of an opposite action current
did not and does not exist,
standpoint,
I
it
was and
is
yet
from a theoretical
a rather crucial point, and
intend as soon as possible to try the point upon
more slowly reacting
nerve,
nearest
the
by
afforded
considered
Meanwhile as regards
approach to direct evidence
" polarisation
the
next
tissue.
this
;
in
my
increment
view
variation of a latent action-current
Indirect evidence
polarising current.
is
the
"
to
be
negative
opposed
is
is
to
the
also afforded
by the abterminal and atterminal or abmortal and
admortal
will
be developed
Let
and
of Eno-elmann and of
effects
me now
puzzling
Hermann,
as
in a future lecture.
ask your attention to another curious
fact,
concerning
glimmering of an explanation
to
which
offer.
I
have
no
LECTURE
ANIMAL ELECTRICITY.
I20
Instead of a froe's nerve there
V.
now a
is
kitten's
nerve upon the two pairs of electrodes p p' e e' (fig.
the frog's nerve, so
is thicker than
it
44, p. 102)
;
by ^^
that our standard deflection
a
this is
the
There
detail.
current
now
I
test
variation in the usual way, and none
though the resistance
the galvanometer
in
circuit
is
large, but
nothing remarkable about
is
of injury.
volt
for the negative
is
to be seen, al-
the exciting as well as in
is
small,
and although the
0-5 volt
1-5
„
2'0
,,
—
Extrapolar (=" electrotonic ") currents of kitten's nerve,
Fig. 50 (2383).
produced by polarising currents of increasing strength from 0*5 to 2 'o volts. (The
standard deflection by o'ooi volt, not here reproduced, had a value of 40 mm.,
so that e.^. the A. and K. currents at 2 volts have an E.M.F. of about 0*0007 volt.)
strensfth of excitation
be
has been no exceptional result
nessed
a
true
I
;
have never yet
from
action-current
malian nerve, placed upon
This
further increased.
still
isolated
wit-
mam-
electrodes within
the
a
few minutes after the death of the animal, whereas
frog's
to
nerve under similar conditions has continued
exhibit
the
after excision.
action-current
The
contrast
for
is
hours and
glaring,
days
and out of
LECTURE
ANIMAL ELECTRICITY.
all
measure with the more enduring
blooded
compared with
as
that
12
V.
1
of cold-
vitality
warm-blooded
of
animals.
Turning our attention
tonic effects,
most
within
which
obvious
the
to the extrapolar or electro-
evidence
we
nerve,
you have just seen, the
as
are,
of
shall
electrolytic
speedily
find
see,
opposite on the side of the
respectively,
Anode and
instead of greater
but the extrapolar
ordinary current diffusion,
on the side of the
effects
for
and
Kathode
of the
Anode than on that of the Kathode as in the
Of course you think of ordinary
frog's nerve.
diffusion,
obtain,
are equal
that
extrapolar currents
ourselves
We
confronted by some paradoxical results.
as you
polarisation
are
not
case of
current
due
to
they are abolished by
crushing the nerve between the leading-in and leadingout electrodes, or by dipping into hot water either the
end of the nerve that
on the leading-in electrodes,
lies
or the end that lies on the leading-out electrodes.
we
put the effects
down
in
phenomena, and
logical
anaesthetic vapours,
So
the category of physio-
proceed
to
test
them by
which as you remember produced
unmistakeable modifications of the extrapolar currents
of frog's nerves.
The
result
by no means satisfactory
we
are most familiar
—
;
is
a
the anaesthetics with which
ether, chloroform, carbonic acid
— do not modify the extrapolar effects
And
as
surprising and
little
in
the least.
there the matter must stand for the present
regards isolated
mammalian nerve.
No
negative
ANIMAL ELECTRICITY.
122
LECTURE
Equal extrapolar currents,
variation.
Kathodic,
Anodic and
judged by the
as
physiological
V.
of
tests
crushing and of hot water, not physiological as judged
by
the
of
test
vapours.
anaesthetic
thoroughly unsatisfactory position of
which, although
I
short
matters
a
from
;
see no issue at this moment, an
must be found.
issue
In
All that
feel
I
you
entitled to say
at this
perplexed stage
how
it
has happened that
that
answered by "yes" and "no" have been many,
is
that
my
will at least realise
experiments on nerves
while on nerves that give no clear answer at
And
experiments have been few.
may
serve
to
throw
into
my
perhaps at this
mammalian
juncture the negative results afforded by
nerve
all
clearer
the
relief
positive results obtained on frog's nerve.
REFERENCES.
(i)
Reymond
289)
("
;
1843 (" Thierische Eiektricitat,"
explained as being polarisation effects by
p.
in
Pfluger's Archiv," v., p.
1872-3
(2)
and named by du Bois-
Electrotonic currents discovered
;
Summary
in
"
vol.
264 vi., p. 312 vii.,
Hermann's Handbuch,"
;
ii.,
p.
Hermann
;
p.
301
vol.
;
ii.,
174).
''Positive
polarisation''
Reymond
and more
in
the
"
first
mentioned
by du
Thierische Electricitat," vol.
fully described
in
the
"
i.,
Boisp. 240,
Berliner Sitzungs-
ANIMAL KLECTRICITY,
berichte," 1883, p. 343
action-currents by
berichte," 1883,
p.
;
LKCTURE
T23
V.
explained as being after-anodic
Hering in the "Wiener Sitzungs445, and by Hermann in " Pfliiger's
Archiv," vol. xxxiii., p. 103, 1884.
[These three
Sanderson's
"
memoirs
are
given
Burdon-
Me-
Oxford, 1887].
moirs."
Vo7i FleiscJil's deflection described in the "
berichte," 1878
;
considered by
sation increment ("
(3)
in
Translations of Foreign Biological
Wiener Sitzungs-
Hermann
Handbuch,"
vol.
ii.,
to be a polari-
p. 167).
means of distinguishing between "physical"
and " physiological " electrotonus, described by Bieder-
EiJier as a
mann
and
in
the
in his "
"Wiener
Sitzungsberichte," 1888,
p.
Elektrophysiologie, p. 693, Jena, 1895.
84;
124
LECTURE
ELECTROTONUS
Influence of acids and alkalies.
{Continued).
Influence of carbonic acid and
Influence of variations of temperature.
of tetanisation.
The
VI.
Bernstein's electro-tonic
action-currents of polarised nerve.
Hermann's
decrement.
polarisation increment.
of Acids and Alkalies.
InfiiLence
— Turning back
to
we have found that
experimental comparisons can be made systematically,
let me next direct your attention to some experiments
that at once suggest themselves when we have adthe
kind of nerve upon which
mitted
the
that
extrapolar
currents
of
nerve
are
caused by electrolytic polarisation.
Looking back
and summarised
selves
what
will
to the series of effects represented
in fig. 47, p. 109,
be the
we
naturally ask our-
effects of acids
and bases upon
An. and Kat.
Reviewing any considerable number of experimental records
in
which A. and K. have been taken
before and after the nerve has been submitted to the
action of a
find
:—
weak
acid or of a
weak
base,
we
shall
ANIMAL ELECTRICITY.
Fig.
Fig. 52.
— Effect
51.— Effect
of
Fig. 53.
of
LECTURE
COj on K, primary
CO^ on A, primary
VI.
I
25
augmentation.
diminution, secondary augmentation.
— Effect of CO2 on A,
primary augmentation.
ANIMAL ELECTRICITY.
126
VI.
That the most prominent and unmistakable
(i)
modifications have been
acidification
slight
LECTURE
an augmentation of Kat.
:
by-
a diminution of Kat. by slight
;
basification.
That An. has been sometimes augmented,
(2)
augmented by weak
usually diminished, but sometimes
and
acidification,
That An. has been but
(3)
affected
little
by weak
basification.
These
do
results
monious inter
sound
not
particularly
nor seem to be held together under
se,
any very obvious
That depends,
law.
I
think,
upon
somewhat narrow range of concentration within
the
which an acid or alkaline reagent
may be
or
har-
entitled to designate
changes.
alkaline
Still
as
what we
effects
characteristic
we may even
at
acid
this
stage pick out as characteristic the augmentation and
diminution of Kat. by acidification and basification
respectively
and we may remark that the augmenta-
An. has always been
of
tion
;
effected
acidification than the diminution of
A
step
distinct
forward
examination of records
in
by weaker
An.
be taken by
will
the
which both An. and Kat.
have been observed on the same nerve before and
after
its
treatment with acid or with
a certain
opposite
same
range these reagents
directions
direction
between
their
but
will
upon the two
unequally,
magnitudes
is
alkali.
have acted
effects,
so
altered.
Within
that
We
in
or in the
the
ratio
shall
now
LECTURE
ANI^NIAL ELECTRICITY.
find
convenient
it
12/
VI.
adopt some conventional ex-
to
The number
pression for that ratio.
expressing the
value of the magnitude of A. divided by the magnitude
of K. presents itself as a natural formula, and
hereafter refer to
We
shall
as the quotient ^/k-
it
now
are
we
able
from examination of
say
to
records in which both A. and K. have been modified,
the
that
characteristic
of
effect
acidification
is
a
diminution of the quotient ^/k, and the characteristic
an augmentation of the quotient
effect of basification
We
are
further
entitled
that acidification affects
causing
polarisation,
effects, their
1.
order of appearance being
1
[
3.
a weak
first
acid,
effect
is
)
'-as
diminution of A.
diminution of K.,
;
:
^u
^
:
the typical
'^
cr
^
erlect.
)
last effect.
missed,
frequently
The second
more frequently we
such as COo.
often obtained pure
decreased
first effect.
Diminished K. as the
The
then
increased
first
Diminished A.
TTT
Increased K.
(
-
the statement
Anodic then Kathodic
first
Increased A. as the
2.
make
to
even with
effect
not
find a large
together with a relatively
i.e.
is
smaller
an absolute diminution of the
quotient ^/k-
These are dry statements
cumbent upon me
to
;
make them,
the grounds upon which
I
it
in
was, however, in-
order to lay open
have concluded that
//ic
ANIMAL ELECTRICITY.
128
LECTURE
chm^adeiastic effect of acidification
VI.
a diminution of
is
the quotient ^Jk, ctnd the characteristic effect of basification
an augmentation of the quotient ^ Jk-
y^^}}}}^'^^}}]]]!^
Fig. 54.
— Effect of a weak
alkaline bath
(KOH.
N
.^
or 0-285 P^r 100)
upon
A. and K.
.FlG. 55.
The
We
— Effect of a weak acid bath
by
in a
upon A. and K.
and of tetanisation.
—
previous lecture that the nerve
is
influence of carbonic acid
have seen
altered
(propionic acid N/jo)
tetanisation precisely as
it
is
altered by
ANIMAL ELECTRICITY.— LECTURE VL
Fig.
Fig.
56.— Action
57.— Action
of
of
COj on
A. and K.
ammonia vapour on A. and K.
'tWW
Fig.
58.— Effect
of Tetanisation
on A. and K.
I
29
—LECTURE
I30
ANIMAL ELECTRICITY.^
carbonic
acid,
tetanisation
we
and
gives
rise
concluded
to
VI.
therefrom
that
an evolution of carbonic
acid within the nerve.
Fig. 59.
— Effect of
COo on
A. (primary augmentation).
Fig, 60. —Effect of Tetanisation on A. (augmentation).
We
are naturally led
to test the effects of car-
bonic acid upon these extrapolar currents A. and K.,
which we have just found to be subject to modifica-
ANIMAL ELECTRICITY.
tion
— LECTURE
by ether and chloroform
have witnessed
the
effects
;
of
Fig. 61.
effects of
carbonic
The
add,
effects
— Effect
may
of Tetanisation
on A. (diminution).
—are
best
be
— and
very characteristic.
given
is
a group
of four
I
may
Their
by the exhibition
of a series of representative experiments.
example,
upon
to test
(primary diminution, secondary augmentation).
produced by carbonic acid
by tetanisation
description
is
upon
acid
prolonged tetanisation.
— Effect of CO^ on A.
Fig. 62.
131
and as soon as we
these currents, our next obvious step
them the
VL
Here, for
such experiments,
in
LECTURE VL
ANIMAL ELECTRICITY.
132
which the
tion
of carbonic acid and of tetanisa-
effects
upon anodic currents have been recorded.
Car-
an augmentation
or a
bonic
produces
acid
either
diminution of these currents.
Tetanisation also pro-
duces either an augmentation or a diminution.
On
we
reviewing a considerable number of records,
should find that
in
the case of carbonic acid, a
the rule, an augmentation of A, the
diminution of A.
is
somewhat
exception
rare
tetanisation,
whereas
;
in
the
case of
although a diminution of A. has usually-
been produced, an augmentation of A. has occurred
frequently
enough not
deserve the qualification
to
of exceptional.
I
think
we may admit
these
results
to rank as
confirmatory evidence of the conclusion that tetanisation gives
rise to
carbonic acid
an augmented A.
;
a slighter effect than a diminished A., and
surprising
perhaps to find the slighter
it
is
effect
is
not
more
frequent by tetanisation than by carbonic acid freely
supplied.
But whether
—
in
Chapter
this
—
these
is,
in
my
and by prolonged
The
opinion, sufficient
experiments
the electro-mobility of nerve
acid
indeed already based
III. the point is
on evidence which
conclusive
be admitted as evidence or not
is
clearly
show
and
that
modified by carbonic
tetanisation.
modifications of the Kathodic current effected
by carbonic acid are more regular than are those of
the anodic current.
The former
appears to be less
ANIMAL ELECTRICITY.
LECTURE
and
in all the
sensitive than the latter,
I
have made up
I33
VI.
experiments
an augmentation of K.
to this time,
has been produced by carbonic acid and by tetanisation.
This
both
A.
in
illustrated
is
and
K.
57 and 58, where
figs.
In both cases the K. cur-
placed under observation.
by carbonic acid
rent has been obviously increased
and by
diminished by carbonic acid
fig.
but the A. current
tetanisation respectively,
marked
alteration
in
fig.
no
exhibits
57,
consequence of tetanisation
in
Presumably
58.
have been
produced
alternately
this
in
case
last
a
in
mean hap-
pens to have been struck between augmentation and
diminution.
—
It
is
a very
The Influence of Temperature.
simple matter to examine the effect of a raised or
lowered
temperature upon
and the
results
at least
All
— are
we have
—
in
the
case
extrapolar
of raised
currents,
temperature
very constant and very characteristic.
to
do
a receptacle that
is
is
to place the
nerve-chamber
packed round with
warmed by
or gradually
the
ice
and
in
salt,
a spirit-lamp, and then take a
continuous observation in the usual way.
I
shall not
tax your patience by asking you to witness such an
observation
slowly
;
to be of
made with
any value
it
would have
to be
the temperature raised or lowered
through a range of 20 degrees at a rate of a degree
a minute.
Moreover, the photographic record gives
a better general view of matters than the observation
itself,
and although
less
interesting perhaps,
is
cer-
ANIMAL ELECTRICITY.
134
more
tainly
(fig.
63),
which
is
is
VI.
such a record
of a series of alternating A.'s and K.'s at
raised from
two
Here
trustworthy.
one minute
are
LECTURE
intervals, with the
1
8° to 40°
principal
temperature gradually
and then allowed
points
a typical one
;
exhibited
firstly
40° the extrapolar currents
to
in
fall.
There
this
record,
the fact that at about
are
somewhat suddenly
diminished almost and sometimes quite to extinction
EiG. 63.
which
is
— Influence of
rise of
temperature upon A. and K.
evidence of their physiological character
;
secondly, the fact that in consequence of the rise of
temperature A. has diminished and K. has increased.
This
last
worthy
is,
point.
I
think, a very characteristic
For referring back
and note-
to the last
two
sets
of experiments, relating to the effects of acidification
and of
tetanisation,
we
find
that
all
three of these
LECTURE
ANIMAL ELECTRICITY.
agents
—
and action
heat,
acid,
provoke a chemical
have as
their
— which
disruption
common
VI.
of
I
35
presumably
matter-
living
an augmented kathodic
effect
polarisability.
And
please notice with
reference to this record,
that there can be no question here of
fallacy
by
This point has of course
of resistance.
alteration
any
been carefully examined by other experiments into
which
it
present
with
is
case,
with
increased
and
currents,
now
not necessary to enter
a raised temperature
conductivity,
the
inc7'eased
and
after the
relation
rise
(40°),
i.e.,
diminished
there
are
K.
with a falling
is
temperature, and cotemporary with
Comparing the
but in the
;
a diminished A.
between A. and K. before
of temperature,
there
is
a very
as was the
evident diminution of the ^/k quotient
case in consequence of acidification, and in conse;
quence of
tetanisation.
The Eledrotonic
inc7'ement.
— There
are two
more
belonging to our subject that
strate
will
and
I
its
Polarisation
cardinal experiments
am
to explain as clearly as
bring to
of the
The
decrei^tent.
anxious to demonI
am
able,
and that
conclusion this preliminary exposition
principal
data concerning
the
electromotive
reactions of nerve.
The
tonic
first experiment
is
to
show
that an electro-
current, like a current of injury,
durine
excitation
— undergfoes
is
a negative
diminished
variation.
ANIMAL ELECTRICITY.
136
We
(Bernstein.)
LECTURE
shall see that this
directions of current
—
is
VI.
true for both
both An. and
that
Kat. are
diminished during excitation.
Let us begin with An., the connections being as
in fig.
64,
with exciting and polarising circuits con-
joined as shown, so that both these currents pass into
the nerve by the
same
pair of electrodes.
lam
I
I
AnelecCroConus.
icm.
I
I
Ka. CelecCroConus.
<
m
i
Fig. 64.
I
first
make
the polarising current, which provokes
an anodic extrapolar current to the right
and
in the
steady
I
the spot
galvanometer
;
now
in the
nerve
that the deflection
is
excite the nerve,
and during the excitation
moves
indicating a diminution of
to the
left,
the extrapolar anodic current.
How
first
—
,
shall
we
best interpret these facts.
formulate them in terms of the usual signs
positive
and negative.
Let us
+ and
During polarisation p'
is
ANIMAL ELECTRICITY.— LECTURE
—/
,
is
each other
then against
being from
and
and
e'
e'
to
reflection
e of
trapolar current,
In relation to
the figure
(fig.
probably
65) and trace
first
the reverse of what
clear to
+
to
at ^
137
Write these signs down
.
give
it is,
as
it
until a
you that as regards ex-
kathode and
e' is
change the signs
—
You
e, i.e.,
makes
+.
^ is least
e is
through.
the current
little
+
e' is
+,
less
e' is
-\-,
VI.
and
e is
—
at
So you
anode.
If
e'.
from
this
point you follow the change produced during excita-
FiG. 65.
tion,
and
you would not go wrong whether you take
—
— and
+
poles at the galvanometer.
are often made, and
one's guard, for
tion
and 4 respectively, or
potentials at 3
must
o-ive
it
an
to
it is
Still
+
their
mistakes
necessary to be carefully on
come out evidently
that excita-
effect neo-ative to the electrotonic
current.
The way
is
in
which
more anodic than
I
prefer to express
e, i.e.,
less zincative,
it
is
this
:
and current
e'
in
the nerve
i.e.,
LECTURE
ANIMAL ELECTRICITY.
130
more
is
from
zincable,
e to
e'
e'.
The
is
to
show
that a polarising
increased during excitation
positive variation.
e,
e to e.
Our second experiment
is
more anodic than
and the excitatory change gives
current in the nerve from
current
is
VI.
—undergoes
a
(Hermann).
connections are as
in fig. 66, as
being perhaps
a Httle more obvious than would have been the case
with polarising current, galvanometer and secondary
N
PolansdCion
/ncremenC
S.
Po/dnsaCion
<
Fig. 66.
coil
in
one
circuit
connected with
[The
single pair of electrodes.
used as shewn
in figs.
the nerve
resistance boxes
10 and 11 on pages
t,t,
by a
r.
R.,
and
38,
enable us to take a convenient voltage (o'l to 0*5) for
the polarising current.]
Usine a Leclanche
cell
ances at 1000 and 14000
voltage of about 0*1,
I
and havino-
ohms
set the resist-
respectively to get a
close the
key
ing circuit giving current from e to
e'
in the polarisin
the nerve.
ANIMAL ELECTRICITY.
The
on
spot
LECTURE
scale to the right.
flies off
magnet, and when
during excitation
39
back
it
is
having
the right,
to
is
The
coil.
by
deflection
the polarising
i.e.,
increased.
is
This
you might have
precisely as
seen
experiment
the
foretold,
never
The nerve
before.
and during excitation
anodic, zincable,
is
bring
steady, excite the nerve
is
it
closing the key of the induction
at e
I
by a considerable movement of the controlling
scale
current
I
VI.
it
gives
current from e to
e
You may perhaps
express this in terms of positive and
negative,
,
i.e.,
with the polarising current.
but by no means so clearly
simple m.atter under the
ment
"
is
title
;
in
fact
this
of " polarisation incre-
one of the well known posers of honours
examinations
in
any candidate
But
physiology.
I
should not advise
"zincable" to his examiner,
to say
only advise him to think " zincable
"
in
I
order to under-
stand the subject.
Let us
fix
the matter by repeating the two experi-
ments with a reversed polarising current.
In the
/
ment)
(Kat.)
nerve
is
is
is
first
experiment (of the electrotonic decre-
Kathodic
from right
less
to left;
Kathodic
and more zincable
at
the
;
at e
e,
electrotonic
during polarisation the
than at e\
is
is
less zincative
i.e.,
is
the electrotonic
diminished.
The second experiment
ment)
i.e.,
and during excitation there
current in the nerve from e to e\
current
deflection
(of the polarisation incre-
obviously the same whichever
way you take
it.
LECTURE
ANIMAL ELECTRICITY.
140
Here
the experiment of the polarisation incre-
is
ment with a sHghtly
The
different circuit.
current, galvanometer, secondary coil
in
one
VI.
The nerve
circuit.
and exciting
currents,
and nerve are
receives the
and gives
polarising
polarising
its electrical
response
through a single pair of unpolarisable electrodes.
The
first
thing to do
is
to see that there
is little
or no current from the electrodes and portion of nerve
between
—
the nerve happened to be injured near
if
one or other of the electrodes, we should have a
current
and on
injury
of
subsequent excitation a
negative variation of that current that might confuse
or mislead us.
The
and
to
next step
is
to set the alternator in
movement
see that the induction shocks rapidly pulsating
and
fro
through the nerve and galvanometer, do
not of themselves give any deflection.
currents were taken too
tion
confused by an
make and
last
initial
strong,
If the induc-
we should be
and terminal kick by the
break shock of the exciting
by a permanent
deflection during
first
and
series,
the series in the
was
direction of the break current, to which allusion
made above
(p.
114).
These two preliminary sources of
error
having
been excluded, we may proceed with the experiment
proper.
I
flies
close a
off
to
key
the
means of the
in the polarising circuit."
right.
I
bring
controlling magnet.
it
back
The
spot
to scale
And now
that
by
it
LECTURE
ANIMAL ELECTRICITY.
is
at rest,
the
to
There
excite the nerve.
I
right,
an
i.e.,
is
increment of
14I
VI.
a deflection
the
polarising
the
reversed
current.
Repeating
of
direction
versed,
experiment
the
polarising
excitatory variation
everything
current,
current
this
viz.,
with
to
is
also to the
is
the
is
and
left,
in this
current, being the
more
zincable spot,
"way
in" of
becomes more
superadded state of excitation.
zincative during the
is
Incre-
form, and you will recognise that in both
cases the anodic portion of nerve, or
There
its
left.
Trace out the rationale of the polarisation
ment
re-
thus "current of action" in the same direc-
tion as polarising current.
These
varieties of effect in accordance with various
combinations of
We
might,
Kat.
with
nometer
circuits,
e.g., test
the
circuit,
Or going back
coil
might readily be extended.
for the
the
in
decrements of An. and
electrotonic
instead of in the polarising circuit.
to
ment, as described
fundamental experi-
our second
in
the
first
lecture
variation of nerve current (p. lo)
into
— the
results of such
circuits.
experiments would come out
precisely as might be anticipated.
Wherever
enters a nerve from an electrode, the nerve
and
zincable,
negative
— we might combine
one the leading-in and leading-out
The
and oalva-
is
current
anodic
whether such current be a polarising
current sent into the nerve, or an electrotonic current,
or a current of injury drawn
o^ frovi
the nerve.
LECTURE
ANIMAL ELECTRICITY.
142
But
VI.
have thought that the possible confusion
I
of ideas resulting from such experimental
complica-
tion migfht overbalance the advantagfe of the exten-
sion of data,
in
and even the
distinct practical
advantage
of being able to test short bits of
certain cases,
living tissue through a single pair of electrodes.
Besides,
the principle has
if
been mastered,
its
manifold applications can present no further difficulty
an allusion
them
to
will
have been
sufficient,
detailed description would be superfluous
;
their
and there-
fore tedious.
An
action-current,
however
whatever circumstances, whether as
tion of
and under
excited,
a negative varia-
an injury current, or as a positive variation of a
polarising current, or as a negative variation of an electrotonic current,
is
due
chemical) inequality between two points.
is
"zincative," resting tissue
Look
is
at this last diagram.
It
summarises
in
nerve
;
I
all
(=
to a physiological
physico-
Active tissue
" zincable."
Is
it
not forbidding
.^
the currents experimentally detected
shall not
undertake to wade through their
redescription in cold blood.
To anyone who
has not
mastered their key, they must remain unintelligible
to anyone who has mastered their key, they will be a
;
legible
matter.
and symmetrical page
in the story of living
ANIMAL ELECTRICITY.
7» icmi_
li
LECTURE
i
H3
VI.
Demdrcdtion
NeS-
i^dr.
Po^yar
I
cm
icjn-
IS
i
IS
i
N
Po/ansdCion
5 PoldrisaCion
Anele cCroConus.
icjn.
I
I
Ka CelecCroCon us.
<
DecremenC
Fig. 67.
<m
.
144
ANIMAL ELECTRICITY.
LECTURE VL
REFERENCES.
Electrotonic decrement
first
Reymond's Archiv.,
Polarisation increment
Archiv., vol.
vi.,
first
p.
described by Bernstein in du Bois-
1866,
p.
614.
described by
Hermann
in Pfluger's
560, 1872; and further explained
Pfluger's Archiv., vol.
vii., p.
349, 1873.
[Previously noticed by Griinhagen, but by
attributed to
a diminution
in
of resistance.
him
(Zeitschrift
fur rationelle Medicin, 1869.)]
Experiments
illustrating the action of anaesthetic
and other
reagents on electrotonic decrements and polarisation incre-
ments, are given in the Croonian Lecture
Trans. R.S., 1897).
for
1896.
(Phil.
Fig. 10.
General plan of apparatus employed to investigate the influence of
reagents upon the electrical response of isolated nerve.
ipon a pair
' COLUMBIA UNIVERSITY LIBRARIES
28
(^P?41
W15
Waller
Lectures on physiology. 1st ser.
On animal el©ctrict*T*'
7