486 
NATURE 
| 
[March 22, 1883, 
My friend Dr. Ferrier has shown that this position is 
due to the different strengths of the various muscles in 
the body. All being contracted to their utmost, the stronger 
overpower the weaker, and thus the powerful extensors 
of the back, and muscles of the thighs keep the body arched 
backwards and the legs rigid, while the adductors and 
flexors of the arms and fingers clench the fist and bend 
the arms, and draw them close to the body.!. The con- 
vulsions are not continuous, but areclonic; a violent con- 
vulsion coming on and lasting for a while, and then being 
succeeded by an interval of rest, to which after a little 
while another convulsion succeeds. The animal gene- 
rally dies either of asphyxia during a convulsion, or of 
stoppage of the heart during the interval. 
When the animal is left to itself the convulsions—at 
least in frogs—appear to me to follow a certain rhythm, 
the intervals remaining for some little time of nearly the 
same extent. 
A slight external stimulus, however, applied during the 
interval—or at least during a certain part of it—will bring 
on the convulsion. But this is not the case during the 
whole interval. Immediately after each convulsion has 
ceased I have observed a period in which stimulation 
applied to the surface appears to have no effect whatever. 
It is rather extraordinary also, that although touching 
the surface produces convulsions, irritation of the skin by 
acid does not do so.” 
The cause of those convulsions was located in the 
spinal cord by Magendie in an elaborate series of experi- 
ments. 
Other observers have tried to discover whether any 
change in the peripheral nerves also took part in causing 
convulsion ; but from further experiments it appears that 
the irritability of the sensory nerves is not increased.* 
According to Rosenthal, strychnia does not affect the 
rate at which impulses are transmitted in peripheral 
nerves ; according to him, however, it lessens the time 
required for reflex actions. Wundt came to the conclu- 
sion that the reflex time was on the contrary increased. 
In trying to explain the phenomenon of strychnia 
tetanus on the hypothesis of interference, one would have 
been inclined by Rosenthal’s experiments to say that 
strychnia quickened the transmission of impulses along 
those fibres in the spinal cord which connect the different 
cells together. 
The impulses which normally, by travelling further 
round fell behind the simple motor ones by half a wave- 
length, and thus inhibited them, would now fall only a 
small fraction of a wave-length behind, and we should 
have stimulation instead of inhibition. 
Wundt’s results, on the other hand, would lead to the 
same result by supposing that the inhibitory wave was 
retarded so as to fall a whole wave-length behind the 
motor one. On the assumption, however, that the fibres 
which pass transversely across from sensory to motor 
cells, and those that pass upwards and downwards in the 
cord connecting the cells of successive strata in it, are 
equally affected, we do not get a satisfactory explanation 
of the rhythmical nature of the convulsions. By sup- 
posing, however, that these are not equally affected, but. 
that the resistance in one—let us say, that in the longi- 
tudinal fibres—is more increased than in the transverse 
fibres we shall get the impulses at one time thrown com- 
pletely upon each other causing intense convulsion, at 
another half a wave-length behind, causing complete 
relaxation, which is exactly what we find. 
This view is to some extent borne out by the different 
effect produced by a constant current upon these convul- 
sions, according as it is passed transversely or longi- 
tudinally through the spinal cord. Ranke found that 
when passed transversely, it has no effect, but when 
* Brain, vol. iv. p. 313. 
2 Eckhard, Hermann’s Handb. d. Physiol. Band ii. Th. 2. p. 43. 
$ Bernstein quoted by Eckhard, of. e#t. p. 40. Walton, Ludwigs 
rbeiten, 1882. 
i 
passed longitudinally in either direction, it completely | 
arrests the strychnia convulsions, and also the normal | 
reflexes which are produced by tactile stimuli. | 
Ranke’s observations have been repeated by others 
with varying result, and this variation may, I think, be 
explained by the effect of temperature. 
Near the beginning of this paper I mentioned that the 
touchstone of the truth or falsehood of the hypothesis of 
inhibition by interference was to be found in the results 
of quickening or slowing the rate of transmission of 
stimuli. 
Heat and cold are the two agents regarding whose 
action in this respect we have the most trustworthy 
experimental data. In peripheral nerves, heat up to a 
certain point quickens the transmission of stimuli, and 
cold retards it. In the spinal cord warmth increases the - 
excitability, and at a temperature of 29 to 30 may of 
itself cause tetanus.!_ Cold also beyond a certain temper- | 
ature increases the reflex excitability. F 
The effect of warmth and cold upon strychnia retangy | 
is what we would expect on the hypothesis of interfer- 
ence. With small doses of strychnia warmth abolishes the 
convulsions, while cold increases them. When large 
doses are given, on the contrary, warmth increases the 
convulsions, and cold abolishes them. 
We may explain this result on the hypothesis of inter- 
ference in the following manner :— 5 
If a small dose of strychnia retard the transmission of 
nervous impulses so that the inhibitory wave is allowed 
to fall rather more than half a wave-length, but not a 
whole wave-length, behind the stimulant wave, we should 
have a certain amount of stimulation instead of inhibition. 
Slight warmth, by quickening the transmission of im- 
pulses, should counteract this effect, and should remove 
the effect of the strychnia. Cold, on the other hand, by 
causing still further retardation, should increase the 
effect. With a large dose of strychnia, the transmission 
of the inhibitory wave being still further retarded, the 
warmth would be sufficient to make the two waves coin- 
cide, while the cold would throw back the inhibitory 
wave a whole wave-length, and thus again abolish the 
convulsions. 
The effect of temperature on the poisonous action of 
guanidine is also very extraordinary, and is‘very hard to 
explain by the ordinary hypotheses, although the pheno- 
mena seem quite natural when we look at them as cases) 
ot interference due to alterations in the rapidity with) 
which the stimuli are transmitted along nervous struc- 
tures. Guanidine produces, in frogs poisoned by it, 
fibrillary twitchings of the muscles, which are welll 
marked at medium temperatures, but are abolished by) 
extremes of heat and cold. Thus Luchsinger has found that, 
when four frogs are poisoned by this substance, and one 
is placed in ice-water, another in water at 18° C., a third 
in water at 25° C., and a fourth in water at 32° C., the 
fibrillary twitchings soon disappear from the frog at o° C. 
and only return when its temperature is raised to about 
18° C. In the frog at 18° C. convulsions occur, which aré 
still greater in the one at 25°C. In the frog at 32° C., on 
the other hand, no trace of convulsions is to be seen; thej™ 
animal appears perfectly well, and five times the dose off?" 
the poison, which at ordinary temperatures would con uf 
vulse it, may be given to it without doing it any harm, saj™ 
long as it remains in the warmth,’ although when it is 
cooled down the effect of the poison at once appears. 
Another cause of tetanus that is difficult to understan 
on the ordinary hypothesis of inhibitory centres is the “ 
similar effect of absence of oxygen and excess of oxygens} 
When an animal is confined in a closed chamber, withou 
oxygen it dies of convulsions ; when oxygen is gradually 
; 
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ting, 
ton, 
Ist, 
oes Recherches critiques et exper. sur les Mouyements Reflexe: 
ine he ‘ “ Q 
* Kunde and Virchow quoted by Eckhard, of. cé¢.fp. 44; Foster, Journ: 
of Anatomy and Physiology, November 1873, p. 45. 
3 Luchsinger, Physiologische Studien, Leipzig, 1882, p. 44- 
