LECT. IX. CURRENT IN LIVING ANIMALS. 179 



Do not suppose that the blood is more apt than any other 

 conducting liquid, to excite contractions in the muscle of 

 the galvanoscopic frog. I let fall a drop of the blood of 

 this same pigeon upon a glass plate, and place two distinct 

 parts of this drop in communication with two points of the 

 nerve of the frog, but it evinces no contraction. 



It is useless to show you, that if I moisten either the 

 nerve of the frog, or the different portions of the muscle of 

 the pigeon, with a saline or acid solution, or, still better, 

 with an alkaline one, the contractions of the frog are more 

 energetic than in the former experiment. These solutions 

 act chemically on the substance of the nerve, or of the 

 muscle. 



The phenomenon which you have witnessed in the pi- 

 geon, takes place in every other animal, whether warm or 

 cold blooded. 



I have recently proved^ that the galvanoscopic frog gives 

 the same signs when we operate upon a wound made in 

 the muscle of a man. 



Contractions are also produced in the frog when we bring 

 the nerve in contact with a muscle separated from an ani- 

 mal. Here is -a thigh of a frog, detached some time since 

 from the body of the animal. I make an incision into the 

 crural muscle, and connect the extremity of the nerve of the 

 galvanoscopic frog with the bottom of the wound, and 

 another point of this same nerve with the surface of the 

 muscle. You immediately perceive that the frog suffers 

 contractions ; you will observe that it will also do so if I 

 repeat this experiment with the thigh of the pigeon or rab- 

 bit, or with a piece of an eel. But if I continue the expe- 

 riment by renewing from time to time the galvanoscopic 

 frog, we perceive that the phenomenon soon ceases, if we 

 employ the muscles of the pigeon or of the rabbit, whilst it 

 continues longer with those of the frog and the eel. 



