LECTURE IV. 159 



the chief criterion of distinction between 

 the two classes. I believe him to have 

 been the first person who broached and 

 established the now generally received opi- 

 nions respecting digestion. His observa- 

 tions and reflections suggested to him, that 

 the liquors secreted by or poured into the 

 stomach, had the surprizing power of dis- 

 solving the dissimilar food by which dif- 

 ferent animals are nourished, and of con- 

 verting it into a substance sui generis ; this 

 being the first and most important step to 

 sanguification, or its ultimate conversion 

 into that nutritive fluid which is distri- 

 buted to every part of their bodies, for 

 their formation and support. 



Mr. Hunter knew that the gastric fluids 

 were neither acid nor alkaline, nor endowed 

 with any predominant quality, such as 

 would induce us to suppose they had these 

 wonder-working powers. He was fully ap- 

 prized of the variety of substances from 

 which different animals thus derive their 

 nourishment. He mentions that the vora- 

 cious caterpillar which eats such quanti- 



