PEOFESSOE :mattetjcci’s electeo-phtsiological eeseaeches. 
369 
the contrary direction, for an equal time, acquires in the second case a weaker secondary 
electromotor power than it would have acquired had it been taken in its natural condition. 
The duration of the passage of the cm’rent increases, within certain limits, the 
secondary electromotor power of a nerve. I have proved the influence of the intensity 
of the current, by putting successively in the circuit a single nerve, and then two nerves 
joined together, so that the intensity of the current was always half for each of the 
latter. This experiment was made with two, six, and twelve elements of Geove. After 
each experiment, I sought the diflerential current by confronting the nerve traversed by 
the whole with that traversed by the half current. The diflerential currents were 3°, 28°, 
and 38°. 
I have also proved that neither the size nor the number of the nerves united by 
superposition exercised any influence on the secondary electromotor power. After 
having subjected four similar nerves to the same current, I made a diflerential pile, 
setting three of these nerves superposed in opposition to one ; and no diflerential current 
was produced. I have sent the same current through the nerve of a frog, that of a 
lamb, and of a fowi. These nerves w^ere of the same length ; and in order to avoid the 
desiccation of the nerve of the frog especially, they were placed under a moistened 
glass bell. After they had been electrolysed, I opposed successively the nerve of the 
frog to that of the fowl, the nerve of the fowl to that of the lamb, and so on : I found 
no diflerential current. Yet each of these nerves, taken separately, gave a current of 
from 40° to 50°, due to secondary polarity. 
I would again recall attention to the result obtained in studying the influence of the 
length of ner\’es. In whatever way the experiments were made, whatever might be the 
nerves employed, a strong diflerential current was constantly found in the direction of 
the longest piece of nerve. We shall afterwards see how this result is modified, according 
to whether the two species of nen e of unequal lengths to be compared have been taken near 
the positive or near the negative electrode; these differences do not, however, alter the 
general result already referred to. The experiment consists in sending the current through 
along neiwe, like the sciatic nerv'e of a lamb. This nerve is electrolysed and divided into 
four equal parts, three of which are left disposed as they were during the passage of the 
current, and the remaining one is opposed to these three. This experiment was per- 
formed by alternating the position of the pieces; a diflerential current of from 30° to 40° was 
constantly obtained, owing to the longest piece. The same effect is obtained from nerves 
of frogs and fowds, whether the operation of cutting the nerve has been made after 
being electrolysed or before. This result cannot be understood unless we admit that 
the secondary electromotor power, which originally is greatest in contact with the 
electrodes, extends successively to all the parts of a nerve traversed by the current. 
I come now to the fact w'hich I consider as most important in the application of 
secondary electromotor power to the explanation of certain electro-physiological pheno- 
mena. This fact is resumed in the following proposition : — 
The secondary electromotor yower of a nerve is not equal in all joints of the nerve^ 
