ON INDUCED CONTRACTIONS. 309 



lead us to admit the evolution of electricity during muscular contraction, while, as 

 certainly, all the other cases described oblige us to conclude the contrary. 



I will now proceed to detail several other new researches upon the phenomenon of 

 induced contractions : but I must first entreat that the reader will excuse my tres- 

 passing on his time with a lengthened account of my numerous experiments : the fact 

 of induced contractions is certainly of such importance, and at the same time so 

 obscure, that it cannot be established except by long and patient researches. 



No one who has once seen induced contractions occasioned by contractions excited 

 by other means than an electric current, can hesitate to admit that this current is 

 not the direct cause which produces them. 



If the nerve of the galvanoscopic frog be applied upon the muscles of the thigh of 

 a frog prepared in the ordinary manner, and the spinal chord be suddenly lacerated 

 with scissors, or with the broken edge of a piece of glass, or by any other means, in- 

 duced contractions very rarely fail to occur. It is however certain that passing an 

 electric current through the lumbar plexuses, the phenomenon of induced contrac- 

 tions scarcely ever fails. 



As I have most frequently resorted to the passage of the electric current for exci- 

 ting contractions, I have taken every possible precaution to prevent any portion of 

 the electric current from invading the galvanoscopic frog or the thighs of the entire 

 frog. The best mode of conducting the experiment, and the way which offers the 

 best chance of success, is to fill a common dinner-plate with Venice turpentine and 

 spread the frog upon it. It is hardly necessary to say that the turpentine should be 

 so dense that the frog cannot sink in it ; care must be had in preparing the galva- 

 noscopic frog not to leave any portion of muscle attached to the nerve. 



Whatever may be the position of the nerve of the galvanoscopic frog relatively to 

 the muscular fibres of the thigh on which it is laid, the phenomenon of the induced 

 contractions always continues. Thus on some occasions I have extended this nerve 

 parallel to the muscular fibres, or I have extended it normally to the said fibres, or 

 in fine, I have bent it in a zigzag, that is, in all directions, and the induced contrac- 

 tions have been obtained in every case and without sensible difference. 



These induced contractions are obtained by applying the nerve of the galvanoscopic 

 frog on the gastrocnemius muscle of the leg. 



I have also attempted, by washing the galvanoscopic frog several times in pure 

 water, to remove any trace of blood or other humours which might be sprinkled over 

 the surface of its muscles, and the induced contractions have equally continued. 



I have cut with a razor, or better still with a pair of scissors, the surface of the 

 muscles ; I have then placed the nerve of the galvanoscopic frog upon the cut sur- 

 face only of the muscles themselves ; the induced contraction has taken place. It 

 has also occurred on disposing the nerve of the galvanoscopic frog upon the muscle 

 so that the extremity of the nerve should fold back over the nerve itself, and thus 

 form a kind of closed circuit. 



2 s 2 



