on the Irritability of Nerves. , 19 
separated, as in the former experiments, it contracted to 11 
inches ; a diminution of J- of an inch. 
The electric fluid, in this last experiment, excited the action 
of the diaphragm, but produced no evident or permanent con- 
traction of the nerve ; and, when the nature of the contraction 
of a nerve is considered, it is not to be expected that perma- 
nent contraction can be ascertained, in any other way than by 
separating intirely a portion of nerve from the rest of the 
system. For the action is continued in tremors along the nerve, 
in quick succession ; and, when the muscle has been excited to 
contract, the complete action of the nerve is finished, and it 
immediately relaxes, or returns to that state which admits of 
a new action. 
This appeared to be the case in several experiments made 
upon the nerves of frogs, and of quadrupeds of a higher order, 
by two different metals, as described by Galvani. In all of 
them, there was a convulsion of the muscle, and a tremor in 
the nerve ; but, such was the rapidity of the effect, that it could 
not be decided that any motion took place in the nerve, ex- 
cept what arose from the agitation produced by the action of 
the muscle. 
The experiments and observations which have been related, 
appear to illustrate an action in the nervous chords, capable of 
producing the symptoms which occurred in the case related in 
the former part of this paper, and also those met with in many 
other diseases, the symptoms of which have never been satis- 
factorily explained. 
The hypothesis of a nervous fluid, although it may explain 
every symptom which originates in the brain, and from thence 
pervades any part of the system, and every symptom which 
D 2 
