LECT. XIV. XV. is ELECTRICITY EVOLVED ? 273 



plexus alone with alkali, we touch with alkali the parts 

 which really constitute the electromotive element, and even 

 in these cases we never succeed in obtaining the signs of 

 the current, if we moisten the whole of the muscular sur- 

 face. 



I may also add, that if we employ an acid solution, taking 

 care to touch with a pencil the lumbar plexus only, and not 

 the muscles of the thighs or of the legs, the deviation is not 

 weakened ; and notwithstanding the contractions excited, 

 are less strong than those produced by the alkali, there is 

 no augmentation of deviation. In order to cause the needle 

 to descend, it is necessary to touch the surface of the 

 muscles with an acid. This same effect takes place with 

 the alkali, and it is, I repeat, in accordance with the ex- 

 periments, already related, upon the muscular elements 

 which have been immersed in acid or alkaline solutions. 



It is, then, only with the pile of entire frogs, or by 

 touching with alkali the lumbar plexuses alone, that we 

 often obtain a slight augmentation of deviation ; and this 

 phenomenon appears when operating in the same manner 

 with acids. By taking into consideration all the experi- 

 ments which I have mentioned, this result cannot be re- 

 garded as contrary to the negative reply that we have given* 

 in an absolute manner, to the question of the development 

 of electricity during muscular contraction. 



However little may have been the attention paid to the 

 exposition of all these facts, it is impossible not to perceive 

 how great is the difficulty which we encounter when we 

 attempt to explain, in the particular case alluded to, why 

 the alkali produces an augmentation of deviation in the 

 proper current of the pile formed of entire frogs. I am 

 inclined to think that, as the alkali excites in the muscles 

 stronger and more permanent contractions than those pro- 

 duced by acids, the contractions ought in most cases to 

 18 



