Feb. 6, 1879] 



NATURE 



32 I 



The simple excitation of the remote end of an electric 

 nerve produces a single "wave, as the simple excitation of 

 a motor ner\-e produces a single shock. In both cases, 

 at the moment of the nerve-excitation produced in the 

 neighbourhood of the electric apparatus or of the muscu- 

 lar apparatus, the amount of delay is sensibly the same, 

 about seven-hundredths of a second. The electric "wave, 

 like the muscular shock, has a phase of increase and a 

 phase of decrease ; the former, as we have seen, is abrupt 



or sudden from one part to another ; the decreasing phase 

 is much more gentle. The same agents modify the wave 

 and shock in the same manner ; heat renders both these 

 actions more speedy and more energetic up to a certain 

 point at which both electric reaction and muscular reac- 

 tion disappear ; cold acts equally upon movement and 

 electric action, rendering both more slow, more feeble, 

 more extended, and at last extinguishes them when the 

 temperature is lowered to about zero C. 



In the complex muscular act which is called contraction, 

 as in the electric act which constitutes the discharge, the 

 elementary phenomena which we have just been con- 

 paring, the waves and the shocks are added on one to 

 another in the same manner ; they succeed each other 

 with a rapidity so great that each has not time to com- 

 plete all the phases before its successor is produced. The 

 floor and the shock are interrupted during their decreas- 

 ing period by a new wave or shock coming to join onfits 



Fig. 12. 



effect to what remained of the preceding act. But, as 

 there are imperfect muscular contractions, cases of te- 

 tanus where the shocks are not completely fused together, 

 not being rapid enough in their succession, so in the 

 same way certain electric discharges present a remark- 

 able discontinuity, such that the elements of the perfect 

 act are seen arranging themselves, the waves following 

 each other with less rapidity, the shocks separated from 

 each other by a larger inter\'al of time. 



Let us now compare the effects of fatigue upon Mus- 

 cular contraction and upon the discharge, as we have 

 compared them upon the muscular shock and upon the 

 electric wave ; we shall see the two acts modified in the 

 same direction. It is even possible to see the torpedo- 

 wave and discharge gradually becoming extinguished, 

 just as muscular shocks disappear under the influence of 

 exhaustion. This gradual extinction of the electric 

 waves is very evident in Fig. li, obtained by means of 

 the electro-dynamograph. 



Poisons which act directly or indirectly upon the mus- 

 cular function modify in the same manner the electric 

 function. Thus strj-chnine, for example, which in a 

 very special manner exaggerates the excito-motor power 

 and that which might be termed the excito-electric 

 power of nervous centres ; a complex reaction, a muscular 

 tetanus on one side and a real electric tetanus on the 

 other, is produced in reply to a simple excitation, the 

 mere touch of the skin, or a slight noise. 



Fig. 12 shows a type of muscular str^xhnine contrac- 

 tion in the frog. Here we obser\-e a diminution of in- 

 tensity produced in the middle of the muscular tetanus 

 between two maxima, one at the beginning and the other 

 at the close. 



In agreement with this characteristic phenomenon, the 

 cause of which is unknown, we observe in torpedo 

 poisoning by strychnine a weakening or interruption 

 towards the middle of the discharge. Fig. 13 shows on 

 line A a t>-pe of this species of interruption which must 

 be compared with that which we have just seen on the 

 tracing of muscular tetanus. 



We might stiU further extend the comparison of those 

 two fimctions, the electric and the muscular, by study- 



FlG. 13. 



ing the action of other fishes, such as the Gyvmoius, the 

 electric ray, &c.; and by showing that the results are 

 identical when heat and cold act upon muscular con- 

 traction and upon the discharge of the torpedo. The 

 preceding paragraphs are sufficient to justify the func- 

 tional assimilation which, let us hasten to say, is in 

 accordance with the anatomical assimilation. 



We shall only add that these identifications are of 

 higher interest than curiosity ; the more oiu: knowledge 



of muscular phenomena and electric phenomena becomes 

 perfected, the more enlightened is our knowledge of the 

 motor nerves. Does the fact that a voluntary discharge 

 of the torpedo is a complex act not prove that the Yolun- 

 tary contraction of the muscles is also a complex act? 

 Very certainly, the comparison of the voluntary contrac- 

 tion of the muscles with the tetanic phenomena pro- 

 duced by electricity or by strychnine, the existence of a 

 muscular sound during the contraction, the quivering or 



