CHANGE IN MUSCLE BY CONTRACTION. 



445 



substance, and this ensues even in the artificial motions that are estab- 

 lished by electric currents in amputated muscles, as is satisfactorily shown 

 by the experiments of Helmholtz. Of these the following synopsis is 

 given by Dr. Day : 



" Powerful muscular contractions were induced by passing an electric 

 current through the amputated leg of a frog as long as convulsions con- 

 tinued to be manifested. The flesh of both legs was then analyzed. 

 The albumen was apparently scarcely affected, the mean of six experi- 

 ments giving 210 per 10,000 of albumen in the electrized, and 213 in 

 the non-electrized flesh. With regard to the extractive matters, it ap- 

 peared that in all the experiments, without a single exception, the water 

 extract in the electrized flesh was diminished, while on the other the 

 spirit and alcohol extracts were increased. The results are expressed in 

 the following tables : 



Change in Muscle after Ekctric Contraction. 

 Alcohol extract from 100 parts recent frog's flesh. 



" The amount of fat was unaffected. No urea could be found in the 

 alcohol extract. 



"There is great difficulty in performing experiments of this nature on 

 warm-blooded animals, in consequence of the rapidity with which iso- 

 lated portions of the muscle lose their contractility. 



" The best results were obtained with decapitated pigeons : 



" The above facts sufficiently show that muscular action is always ac- 

 companied by a chemical change in the composition of the acting mus- 

 cle." It appears that after electrization the alcohol extract increases be- 

 tween 24 and 38 per cent. ; the water extract diminishes between 24 and 

 20 per cent. ; the spirit extract increases between 13 and 22 per cent. 



I therefore regard disintegration of the muscular structure as the prim- 

 itive act, so far as the fibril itself is concerned, and contraction as the 



