PHYSIOLOGY. 



also by imitations ; and they are particularly excited by pro- 

 pensities to remove pain and uneasiness, which operate more 

 frequently on respiration than upon any other function. 



CXCVL The consideration of the effects of respiration on 

 the animal fluids is delayed till the nature of these fluids shall 

 have been more generally considered. 



SECT. IV. 



OF THE NATURAL FUNCTIONS. 



CXCVII. The animal body from a small beginning grows 

 to a considerable size, and, at the same time, from the period of 

 the birth, during the whole of after life, the body suffers, by 

 various means, a daily and considerable waste. 



CXCVIII. The increase of bulk, therefore, must be acquired, 

 and the daily waste supplied, by matters taken into the body, 

 the most part of which, from the presumed purpose of them, we 

 name ALIMENTS. 



CXCIX. A great part of these aliments, as taken into the 

 body, are of a different nature from the matter of the body itself, 

 or at least are in such a state as not to be fit for being imme- 

 diately applied to the purposes of it ; they must, therefore, be 

 changed, and fitted to the purposes of the economy by powers 

 within the body itself. 



CC. The conversion, or assimilation pf the aliments to the 

 nature of the solids and fluids of the animal body the farther 

 changes of these fluids, for various purposes, by secretion and 

 the application of some part of them in nutrition, or in increas- 

 ing the growth of the body, make what are called the NATURAL 

 FUNCTIONS. 



CHAP. I. OF DIGESTION. 



CCI. The term digestion is commonly employed to signify 

 the function of the stomach alone in changing the aliments ; but, 

 in this chapter, we are to consider all the changes of these as 



