Chap. 35.] Experiments on dead Animals. 355 



body, and lay bare the fciatic nerve. Place the 

 nerve in contact with a piece of zinc, and let its foot 

 reft on a piece of filver ; on bringing the two metals 

 into contact, the mufcles of the limb will be con- 

 vulfed. 



If a piece of brafs wire is made to touch at the 

 fame time the metals difpofed as above defcribed, 

 a communication will be formed between them, and 

 the contraction of the mufcles will equally take 

 place. 



If the nerve is made to reft on a piece of zinc, 

 and the zinc is touched with a plate of filver held 

 in one hand of the operator, while with the other he 

 takes hold of the foot of the frog, the influence will 

 pafs through the body of the operator, and the limb 

 will alfo be convulfed. Thefe experiments muft be 

 performed before the nerve becomes dry by expofure 

 to the air. 



In order that thefe contractions mould be produced, 

 it is not neceflary that either of the metals (liould be in 

 actual contact with the animal in which the convulfions 

 are to be excited ; as the interpofition of pieces of 

 boiled or putrid beef were found by Dr. Monro not to 

 prevent the effect. 



By an experiment of Dr. Fowler the fame fact is 

 proved. He found that if a frog, of which the head 

 mould be firft cut off, is divided into two parts, juft 

 above the origin of the fciatic nerves, and put into a 

 bafon of water, the hind legs may be thrown into ftrong 

 contractions, by bringing zinc and filver into con- 

 tact with each other, at the diftance of at leaft an 

 inch from the divided fpine, fo long as they are kept 

 nearly in a line with it. Water in this cafe is the only 

 communication between the metals and the origin of 

 the nerves. 



A a 2 Dr. 



