PEOFESSOE MATTEFCCI’S ELECTEO-PHYSIOLOGICAL EESEAECHES. 
365 
extremities of the external surface of the two muscles with the extremities of the 
galvanometer. Thus it is found that the electromotor power of eight or ten elements or 
pieces of nerve of the same length is equal to that of a piece of muscle of the same 
length taken from the same animal. 
I shall now describe the principal experiment made with the view of proving the 
development of secondary polarities in a nerve. Before commencing the experiment, I 
ascertained that no sign of current was obtained by touching any two points of a nervous 
filament, equidistant from its extremities, with the extremities of the galvanometer. I 
also ascertained that two sciatic nerv’es of a fowl or a rabbit, joined together either by 
bringing into contact the two distal extremities or 
the two proximal extremities, gave no sign what- 
ever of current if these two nerves had not previ- 
ously been subjected to the passage of electricity, 
and if the experiment had been properly prepared. 
By due preparation of the experiment, I mean it to 
be understood that the contact between the two 
pieces of nerve ought to be either between the two 
surfaces or the two transverse sections of these neiwes, 
and never between the surface of the one and the transverse section of the other. In 
order to ensure this result, the two pieces of nerve should be laid on the gutta-percha 
holder, so as to establish the contact either of their surfaces or of their transverse sections 
on the middle of the holder, while the two opposite extremities of the nerves hang down 
over the two opposite sides of the holder. 
The leading experiment is performed either by laying a nervous cord upon two pla- 
tinum wires, or by placing this cord upon two cushions of flannel or paper soaked with 
spring water, communicating with the poles of a pile. The experiment may also be 
made by preparing a fowl and a frog so as to leave their limbs united to the two 
sciatic nerves, and these nerv'es to a portion of the spine. An electric current from 
a pile of eight or ten elements is then sent through the nerves for a longer or 
shorter time. After the nerv^es have been thus traversed by the current, they are laid 
on the gutta-percha holder and put into communication with the galvanometer. The 
needle derfates, and indicates that the nerve is traversed, in the portion which was placed 
between the two electrodes, by a current the direction of which is opposite to that of the 
pile, and which lasts a certain time. 
Signs of secondary current are also obtained by touching with the extremites of the 
galvanometer those portions of the nerve which have not been traversed by the current, 
that is, between the points touched by the electrodes and the points of the nerve which 
hang outside of the circuit. It is important to observe that the direction of the currents 
thus obtained is the same as that of the pile-current between the electrodes. I have 
constantly remarked that the current thus obtained between the points in proximity to 
the negative electrode and the external portion of the nerve on that side, is much 
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