138 
PEOEESSOE MATTETJCCI’S ELECTEO-PHTSIOLOGICli EESEAECHES. 
these cushions are left for a certain time in contact, the needle rests at 0^, and no sign 
of current is visible on reopening and closing the circuit again. 
Exp. 1. I lay on the quadrant of the galvanometer, exactly in contact vith the end of 
the needle in its state of equilibrium, a solid body, which may be either a piece of marble 
or glass, provided it is dry and polished : the needle resting against this support is pre- 
vented from deflecting in one direction, and is free to move only in the opposite. I then 
lay on the usual strip of gutta-percha either one gastrocnemius, or flve or sis of these 
muscles so as to form a pile ; I close the circuit in such a way that the deflection cannot 
take place in the direction in which the needle is prevented from moving, and I leave it 
closed for some seconds. I then withdraw the pile rapidly, and close the circuit between 
the two glasses immediately. The' needle remains motionless ; there is therefore no 
sign of secondary polarity; and it was foreseen that, in emplo}-ing this method, there could 
be none, although the electromotive power brought into action was much stronger than 
that with which we were to operate subsequently. 
Exp. 2. I prepare a vigorous frog which I reduce to two thighs, one of which only is 
left with its lumbar nerve intact ; this nerve is supported on a piece of gutta-percha 
destined for the purpose. I close the circuit by touching indifiFerently any two points of 
the thigh, which are not necessarily the extreme points ; it is enough if there be a distance 
between them of about 12 or 15 millimetres. With a common galvanometer the deflec- 
tion is small ; with the most delicate one it varies fi’om 50° to 60° and upwards, in the 
direction of the usual current of the thigh, that is, in the dmection of the current of the 
gastrocnemius. I had left the other thigh, though it ought not to form paid of the cir- 
cuit, in order to avoid the possibility of the interior of the muscle in the upper part of 
the thigh submitted to experiment becoming part of the cii’cuit. Hailng allowed the 
needle to fix, keeping the thigh in its place by pressing slightly on it with a piece of 
gutta-percha (which occasions little or no variation in the deflection), 1 begin to excite 
the nerve with an extremely weak interrupted current ; for this pm-pose 1 prefer a small 
pile of zinc and platinum wires which I hold in hand, to an electro-magnetic machine, 
although I do not believe it probable that the use of that machine can cause any error 
in the experiment. At the very moment in which the thigh begins to contract, the 
needle descends towards 0°, and the contraction continuing, the needle passes beyond it 
and comes to rest on the opposite side. When we cease to excite contraction, or when 
the contractions are weakened from natural lassitude of the muscle, the needle descends 
again slowly and deflects in the same direction as at fii’st, but rarely attains the point 
reached at the beginning. This experiment, repeated mth the gastrocnemius, gives the 
same result, as also with the entire muscles of other animals. I prefer, however, as AAill 
be readily miderstood, the use of a single entire thigh of a frog, in order that the mus- 
cular current which circulates at the beginning of the experiment may be as small as 
possible. Among the numerous experiments which I have made, the muscular cimrent 
has often been excessively weak, sometimes so weak as to leave the needle at 0°. During 
the contractions the deflection was in the same direction as that found when the needle 
