ON INDUCED CONTRACTIONS. 311 



By operating upon rabbits or upon dogs, I have been able, with the electric current, 

 to act upon the nervous filaments that run to the kidneys, to the stomach, and 

 to the intestines : when the nerve of the galvanoscopic frog was extended upon the 

 different parts in the same conditions as for the muscles, I never obtained any sign 

 of induced contraction. 



I have also sought to discover if there was contraction induced by applying the 

 nerve of the galvanoscopic frog upon the excited nerve. For this purpose it is suf- 

 ficient to prepare two galvanoscopic frogs, and to extend the nerve of the one upon 

 the nerve of the other, in the points nearest to the leg. To perform the experiment 

 with every care, the two frogs are disposed upon turpentine. Then, either with the 

 current or with some other stimulant, the superior points of the nerve of the frog, that 

 I shall continue to call inducing, are erected. There is no induced contraction in 

 the galvanoscopic frog, although this contraction immediately occurs, if its nerve is ex- 

 tended over the gastrocnemius of the other. It is needless to say that in using the 

 current to excite the inducing contraction we must never place either of the elec- 

 trodes of the pile in contact, or in proximity to the nerve of the galvanoscopic frog. 



It is proved by the above experiment that an excited nerve, and one in which is 

 certainly propagated that cause, whatsoever it be, which awakens contraction in the 

 muscle and sensation in the brain, does not act upon the nerve of the galvanoscopic 

 frog placed in contact with it. I will also add the following experiment. I have 

 uncovered the brain of a frog prepared in the ordinary method with the greatest 

 possible care, and I have extended upon it the nerve of the galvanoscopic frog. 



In various experiments thus tried, I have applied the current sometimes direct, 

 sometimes inverse, upon the lumbar plexuses, and in others I have touched these 

 plexuses with potassa, and I always obtain the contractions in the lower limbs and 

 convulsions in the back. However, I have never found signs of induced contractions 

 in the galvanoscopic frog that was extended upon the brain. The induced contrac- 

 tions are therefore originated solely by the muscle in contraction. 



I have sought to discover how these induced contractions grow weak, by causing 

 them to be originated by means of a muscle whose own contraction was induced. In 

 a word, I have examined the induced contractions of the second and third order, &c. 

 For this purpose I prepare various galvanoscopic frogs, and one in the ordinary 

 manner, and I dispose them in the following way. Upon the muscles of the thighs 

 of the entire frog I extend the nerve of a galvanoscopic frog : upon the gastrocnemius 

 of this, I extend the nerve of another galvanoscopic frog, and so on in succession. 

 The whole is placed upon turpentine. On exciting the contractions of the entire frog by 

 making the current pass through its lumbar plexuses, I have seen in many instances 

 three galvanoscopic frogs contract, and all with nearly the same vivacity. The con- 

 tractions are never wanting in two frogs, but I have never been able to perceive four 

 contracted. There is therefore an induced contraction of the first, the second, and 

 the third rank. Before coming to the consequences to be drawn from the above- 



