ELECTRO-PHYSIOLOGY. 329 



ments after death, the muscle of tlie rabbit predominated. I have myself made 

 these comparisons by operating upon living animals, and with results still more 

 decisive. 



Second j)roposition. — " The nerve does not directly exercise any influenco 

 upon the electro-motor poAver of the muscle." 



We have before seen that by leaving to the muscular elements the nervous 

 filament, and introducing it into the circuit, we only produce a weakening of the 

 muscular current. When the opposite battery is formed by two muscular ele- 

 ments, one without the nerve and the other with the nerve placed in circuit, 

 since by this arrangement the internal resistance is excluded, there is no differ- 

 ential current — a fact which indicates that the electro-motive force of the muscle 

 is independent of the presence of the nerve. We may also experiment on 

 pieces of muscle in wliicii have been left, now the nerve which ramilies therein, 

 and now the nerve which issues from it. In both these cases it will be found 

 that the nerve acts only as would a piece of wet thread, which is a bad con- 

 ductor, in contact with a certain part of the muscle. Under the above propo- 

 sition might be comprised the results obtained by a comparative study of healthy 

 muscles and those affected with nai-cotics. The general result, is that the elec- 

 tro-motor power of the muscles of these animals, if they died after having under- 

 gone contractions more or less violent and prolonged, is diminished. The same 

 occurs in the muscles of animals killed with the poison of curare. We shall 

 see in the sequel, in speaking of the electrical phenomena of muscular contrac- 

 tion, how we have succeeded in interpreting the diminution of the electro 

 motor power of the muscles in Avhich, by the action of the poison, contractions 

 have been excited. 



Third irroposition. — "All the physico-chemical actions which modify tho 

 muscular irritability act also on the electro-motor power of the muscles." 



1 shall content my.-<elf with adducing two or three precise experiments which, 

 in different cases, verify this proposition. We have here two vessels contain- 

 ing frogs ; in one are some taken but a few hours from the fens where they 

 naturally live ; in the other, some taken several weeks ago, and consequently much 

 enfeebled. Whether we operate on the gastrocuemians or on the half thighs, 

 thjere will constantly be realized, with the usual method of the double battery, 

 a differential current which will evince that the electro-motor power of the 

 muscles of the fresh frogs is greater than that of the muscles of the frogs which 

 1 denote as enfeebled. The effect of the enfeeblemeut is always more manifest 

 in the gastrocnemiau muscles than in the half thighs. 



The influence of refrigeration on the muscles may be shoAvn in a very distinct 

 manner, I prepare a: certain number of gastrocnemiau muscles taken from 

 different frogs, and introduce a portion of them into a glass tube, which I 

 immerse in a frigorific mixture of ice and salt. After two or three minutes I 

 form the usual double battery with a gastrocnemius which has not been in 

 the mixture, and with one which has undergone refrigeration. There will 

 constantly be observed a great diminution in the electro-motor power as the 

 effect of the reduction of temperature. By prolonging the refrigeration for 

 fffteen or twenty minutes, the muscles lose this property entirely, while, if the 

 process of cooling has been of brief duration, they reacquire, on regaining the 

 ordinary temperature, a portion of the electro-motive force. An effect analo- 

 gous to that of a reduction of temperature is produced by its elevation. The 

 fact may thus, at least in part, be explained, why it is that frogs, as well in tho 

 depth of winter as in the hottest weather, yield with their muscles much weaker 

 electric currents than in the intermediate seasons. 



1 have sought to ascertain whether muscles, entire or divided, left for a cer- 

 tain time in hydrogen, oxygen, or carbonic acid gas, or within the vacuum of 

 the air pump, underwent variations in their electro-motor power. I have 

 discerned no difference, for even the effect produced by operating with hydrogen 



