THE PHYSIOLOGICAL ACTION OF THE ELECTRIC CURRENT. 
487 
is the immediate consequence of the contact of the liquid with this nerve. No such 
effect follows the contact of oil or turpentine with the nerve. It is very evident that 
the conducting liquid bathing the nerve stops the current in the nerve itself, being a 
better conductor. The contact of a muscular mass with the nerve produces the 
same effect as a liquid conductor. Ail this proves that the conducting power of the 
nerve is inferior to that of muscle and of distilled water. 
I have repeated the above experiments upon living frogs. I prepared them in such 
a manner as to leave the two limbs united to the back by the lumbar nerves alone. 
I suspend this frog by hooks fixed to his lower jaw, and I pass the current from one 
paw to the other. I repeated the experiment frequently, and have always observed that 
after a certain time, varying from twenty-five to forty minutes, the inverse limb alone 
contracted on breaking the circuit. Thus it appears that it requires a somewhat 
longer time to produce the same effect with the electric current upon the nerve of 
the living animal, than upon the dead one. 
It thus remains clearly proved that the passage of the electric current through a 
mixed nerve modifies the excitability of this nerve in a very different manner, accord- 
ing to its direction : the nerve traversed by the direct current loses its excitability 
much more rapidly than that which is traversed by the inverse current. I ought here 
to add, that hitherto we have no experiment proving that a nerve subjected to 
the passage of the inverse current loses its excitability otherwise than it would 
have done if merely left to itself. I return to the exposition of facts. Out of ten 
frogs submitted to the experiment above described, frequently eight at least present 
the following phenomenon : — On breaking the circuit after the current has circulated 
twenty-five or thirty minutes, the inverse limb alone contracts ; but this contraction 
does not cease immediately after the circuit is broken. The inverse limb continues 
to be contracted, exhibits, that is to say, symptoms of tetanus. I have frequently 
witnessed the contractions lasting from ten to twenty seconds. If without waiting 
till the contractions cease the circuit is again closed, the limb, which was stiff and 
contracted, will be observed to give one more violent contraction when the circuit is 
in the act of being closed, and then immediately return to its natural state. It is 
not a rare occurrence to find frogs which present these phenomena after a lapse of 
three or four hours of experiment. These phenomena exhibit themselves equally 
when the passage of the current is confined to the nerve alone, to the exclusion of the 
muscle*. There is one observation which it is important to make with reference to 
the phenomena just alluded to. I have repeatedly stated that when the current 
has circulated for twenty-five or thirty minutes in the prepared frog, the only contrac- 
tion is that of the inverse limb on opening the circuit. The circuit may be frequently 
* This strong and enduring contraction which seizes the inverse limb upon breaking the circuit, offered me a 
favourable opportunity of witnessing the phenomenon of induced contraction. The nerve of the galvanoscopic 
frog should be stretched upon the muscles of the thigh of the inverse limb. On breaking the circuit the gal- 
vanoscopic frog becomes contracted, and persists in this state as long as the inverse limb remains contracted. 
