SECRETION. 249 



tricky is, no doubt, an important agent in all these processes, 

 but in the absence of all certain knowledge as to the mode 

 in which it is excited and brought into play in the living 

 body, the chasm can for the present be supplied only by 

 remote conjecture. 



The process which constitutes the ultimate stage of nutri- 

 tion, or the actual incorporation of the new material with 

 the solid substance of the body, of which it is to form a part, 

 is involved in equal obscurity with that of secretion. 



nous ramifications, though on a much smaller scale, has been discovered by 

 Jacobson, in the kidneys of most fishes and reptiles, and even in some birds. 



VOL. II. 32 



