370 
PEOFESSOE MATTEUCCI’S ELECTEO-PHYSIOLOGICAL EESEAECHES. 
hdng much stronger in the portion of the nerve near the positive electrode, than in the 
portion near the negative electrode: this difference is greater in a nerve traversed hy the 
current in the direction contrary to that of its ramification, than in a nerve traversed hy 
the current in the direction of its ramification. 
I have verified this proposition by experiments on sciatic nerves of fowls, frogs, and 
rabbits. I begin by laying two sciatic nerves of equal length on the cushions of two 
glasses filled with spring water. These nerves are disposed in the same way as to their 
ramification, that is, the voltaic current in both nerves must be either direct or inverse. 
After the passage of the current, the two nerves, each of which has been traversed by 
one half of the current, are opposed to each other in the usual way on the gutta-percha 
holder. I never found any indication of differential current, although each of these 
nerves, taken separately, gave a very strong secondary current, having the same direction 
whatever might be the position of the two points of the nerve touched by the extremities 
of the galvanometer. 
In order to show the difference of secondary electomotor power taken at points of the 
nerve nearest to the two poles, I cut an electrolysed nerve into two equal parts, and 
oppose these parts to each other ; a differential current of 25 to 30 and more degrees is 
constantly obtained from the portion of nerve nearest to the positive pole. This experi- 
ment was made on a long sciatic nerve of a lamb. After having electrolysed this nerve, 
I cut it into a certain number of equal parts, which I opposed to each other, and I found 
constantly a differential current of 25° to 30° and more from the portion of nerve near 
the positive electrode. 
The experiment was again made on a long sciatic nerve of a lamb. This nerve, after 
ha\ing been electrolysed, was cut into a certain number of equal parts, which were then 
set in opposition two by two and tested with the galvanometer. The differential current 
obtained for each couple was always determined by the portion of nerve near tiie 
positive electrode ; and this intensity increased -with the distance which separated the 
two pieces of nerve considered in relation to their natural position. 
The infiuence exercised by the direction of the current which developes secondary 
electromotor power in a nerve, relatively to its ramification, may be demonstrated by 
repeating the experiment, already so often described, upon two sciatic nerves taken from 
a fowl or other animal, with this difference, that the two nerves (laid side by side) must 
be disposed so that the current may traverse one nerve in the direction of its ramification, 
and the other nerve in the opposite direction. As the current is divided in half, if these 
nerves, after having been electrolysed and then set in opposition, present a differential 
current, this current must be attributed to a difference of effect corresponding to the 
direction of the current through the nerves relatively to their ramification. This result is 
obtained either by opposing the two entire nerves, or, still better, by dividing one of these 
nerv es into two equal parts and opposing these halves. 
In a great number of similar experiments performed on nerves of different animals, I 
have constantly found a differential current, by which it is proved that a nerve traversed 
