PHYSICAL AND LITERARY. 29^ 



mals, provided with like fyftems of 

 nerves and vefTels, fufFer in a fimilar 

 way from the application of the fame 

 medicine ; and if this medicine can be 

 proved to affedl the one fpecies folely 

 through the nerves to which it was pri- 

 marily applied, or folely after being ab' 

 forbed and mixed with its blood j it may 

 be fuppofed to affedl the other in the 

 fame manner.— —^Which fuppoficion, I 

 imagine, will be readily admitted, efpe- 

 cially if it is confidered, that the elFe(5ls 

 of the fame medicine applied to delicate 

 and robuft perfons are often as unlike, 

 as where it is applied to two different fpe-* 

 cies of animals. 



Sotne preliminary FaBs referred to in the fol* 

 loiving EJJayt the truth of nvhich I have 

 Jiifficiently afcertained by repeated Expe- 

 riments, 



I. There is but one auricle and one 

 ventricle in the heart of a frog j and only 

 one artery arifmg from the ventricle, 

 which fupplies the air-veficles or langs» 

 fts well as the red of the body. 



2. The 



