578 



soon disappear. Now, after having opened the circuit of the galva- 

 nometer, irritate the nerve of one of the segments, by pinching, by 

 the interrupted electric current, or in any other way ; or prick the 

 piece itself with a needle. The portion of organ thus stimulated 

 will give several discharges in succession, and a rheoscopic frog's limb 

 with its nerve applied to the part will each time be thrown into vio- 

 lent convulsions. If, after this, the galvanometer be applied as be- 

 fore, there will be a very strong deflection in a direction answering to 

 the segment stimulated. This deviation endures for a short time, 

 but gradually becomes less, so that in a few minutes the effect of the 

 two segments is equal. Stimulation now of the other segment will 

 in like manner render its electricity predominant. These alterna- 

 tions may be repeated several times, but naturally the effect becomes 

 less and less marked. 



" Thus the electromotive apparatus becomes charged and acts in- 

 dependently of the influence of the nerves, but that influence renews 

 and renders persistent the activity of the apparatus. We know, 

 moreover, that the discharge, which is only a state of temporary in- 

 creased activity of the organ, is brought on by an act of the will in 

 the live animal, or by the excitation of the nerves of the organ. 



" I shall not enter now into further details respecting my recent 

 experiments on the Torpedo, but I venture to think that we have 

 really made a step towards clearing up the theory of the animal elec- 

 tromotive apparatus. The organ of the Torpedo does not, under the 

 influence of the nerves, act as an induction apparatus ; the operation 

 seems more analogous to that of a 'secondary pile,' created, through 

 the influence of the nerves, in each constituent cell of the organ. 



" The case is very different in muscular action, the changes occur- 

 ring in which are better understood now that we know the pheno- 

 mena of muscular respiration. I do not here refer to the variation 

 of the muscular current which takes place at the moment of con- 

 traction. In that case it would appear from experiment, as I lately 

 showed, that there are indications of a current in an opposite direc- 

 tion ; but the conditions of the animal structure in action are so 

 complex that no inference can be drawn as to the intimate nature of 

 the phenomenon. It is otherwise, however, in comparing muscles 

 which have been left at rest with muscles which have been fatigued 

 by repeated contraction. Being still engaged in the investigation of 



