720s 
tractions of the galvanoscopic leg will not take 
place. If, however, a slight tear be made in 
the gold leaf, then the nerve may be excited. 
It is possible that this may arise from the 
electricity being carried off by the gold leaf, so 
that it does not affect the nerve at all. Matteucci 
never succeeded in obtaining the induced con- 
tractions when a solid body was interposed 
between the nerve and muscle, however thin 
it might have been and whatever might be its 
nature ; for this purpose he used flakes of mica 
extremely thin, flakes of sulphate of lime, gold 
leaf, paper smeared with glue, and ieaves of 
vegetables.* 
On the other hand, in interposing some sub- 
stances which are known to be bad conductors 
of electricity, the contractions were obtained. 
The thackat contractions may be excited if the 
nerve be laid upon the skin over the muscles of 
the inducing frog. ‘The experiment,” says 
Matteucci, “ never fails of success, whether the 
inducing contraction be excited by the electric 
current or by any stimulus applied to the lum- 
bar plexuses of the inducing frog.”” The use 
of a very bad conducting body, Venice turpen- 
tine, did not prevent the induced contractions. 
The nearly solid Venice turpentine was ren- 
dered more or less liquid by adding to it a little 
of the volatile oil ofturpentine,and with this the 
muscles were smeared over, and the nerve of 
the galvanoscopic frog was wetted. To prove 
the bad conducting powers of the mixture em- 
ployed, one pole of the exciting pile was ap- 
plied to the muscle and the other to the galva- 
noscopic frog without exciting the least con- 
traction. Yet the contractions were induced 
in the galvanoscopic frog by stimulating the 
muscles of the thigh. This experiment clearly 
proved, as Matteucci remarks, that the induced 
contraction may be excited through a stratum 
of an insulating substance that prevents the 
propagation not only of the muscular and proper 
currents, but also of that current which excites 
the inducing contraction. 
We are forced then by the results of the re- 
markable experiments above detailed to adopt 
the conclusion at which Matteucci has himself 
arrived—that there is no current of electricity 
in the act of muscular contraction. What then 
is the evolved force? It is either an electric 
discharget or a force very analogous to electri- 
city, affecting nerves in a similar way, travelling 
apparently with great rapidity, traversing bodies 
which the galvanic current cannot traverse, and 
yet restrained by substances which freely con- 
duct it. 
I confess myself at a loss to understand how 
Matteucci comes to regard this asa phenomenon 
of the nervous force. In truth, it is a pheno- 
menon which accompanies muscular contrac- 
* Phil. Trans. 1845, On induced contractions. 
t From a letter addressed to M. Dumas by Pro- 
fessor Matteucci, and pnblished in the Comptes 
Rendus for March 15, 1447, it appears that he now 
is rather disposed to regard it as an electric dis- 
charge, as he says, “‘ C’est aprés avoir prouvé que 
des décharges electriques de la bouteille tellement 
faibles qu’elles ne pouvent étre montrées par aucun 
instrument, excepté par la grenouille, que j’ai 
pensé que la contraction induite pouvait étre duc a 
une décharge electrique de ce genre.” 
PHYSIOLOGY OF THE NERVOUS SYSTEM. 
tion, and has no relation to the nervous force, 
excepting so far as that is the excitant of the 
muscular action. The essential point of the 
phenomenon is, that during the contraction of 
a muscle a nerve which is laid on it is stimu 
just as it would be by electricity, and causes 
the muscles to which it is distributed to contraet. 
The electric discharge from a muscle which is 
excited to contract through the exercise of 
vous power is in close analogy with the electric 
discharge from the electrical organ 8 
Gymnotus or Torpedo, which is excited through 
the same agency. 7 
Now the proved existence of a muscular 
force, the developement of which is accompa. 
nied with heat, and most probably electricity 
and in some instances, if the statements o 
Quatrefages be correct, with light, justifies us in 
adopting the opinion, as regards the nervous 
force, that this is of an analogous kind, yet exhi- 
biting still less resemblance to electricity than 
the muscular force; and it strikingly illustrates 
the remark of Faraday, that if there be 
for supposing that magnetism is a higher 
tion of force than electricity, so it may well be 
imagined that the nervous power may be of 
still more exalted character and yet within th 
reach of experiment. 
We are a led to these conclusions resp 
ing the muscular and nervous forces. 
1. That both are polar forces and in elo: 
analogy with light, heat, electricity —magnetist 
2. That either may be excited by or trans 
formed into the other—the nervous may & 
the muscular, or the muscular the nervous. 
seems not improbable that it is by this 
of the muscular upon the nervous force 
muscular sense is developed, and as Matteue 
has ingeniously suggested, many moven 
independent on the will, yet following: oth 
which may be voluntary or otherwise, may rest 
from the same cause. 
3. That the same analogy which exists b 
tween electricity and magnetism is found b 
tween these organic polar forces ; the museulg 
being more nearly allied to the former, the 
vous to the latter. : 
4. Both these forces are dependent on 
healthy nutrition of their respective tiss 
muscle and nerve, and the slightest distu 
in that process in either tissue will 
affect the intensity of the force. 
5. Nevertheless there is a certain mutual: 
pean between these two tissues and t 
orces; for the exercise of each is, within cer 
limits, impossible without the other; am 
this exercise is necessary to maintain he 
nutrition, so these forces are to a certain ¢ 
dependent on each other for their normal ¢ 
lopement. The practitioner in medicine 
duly appreciate the great importance 
conclusion. 
The mutual reactions of the nervous 
muscular forces constitute a new and hi 
important field of inquiry, which, if duly 
vated, may clear up many obscurities im 
physiology and pathology of the nervous sy: 
Having thus far considered certain g 
ties in the physiology of the nervous §) 
we may now proceed to inquire into the 
7 
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a 
