Food. 289 



iherearc animals that grind their food in another manner^ as for in- 

 stance, fowls, whose gizzards answer to them the purpose of teeth. 

 After being ground, and reduced to a pulp, the food passes into the 

 stomach, where it undergoes new changes, and is converted into a 

 ^appy mass called, by physiologists, chyme, which has no resem- 

 blance to the food when first introduced into the stomach. 



This latter fact being so indisputably plain and evident, naturally 

 excited attention, and it long ago became an object with philosophers 

 and physiologists to accertain, not only the nature of these changes 

 but, also, the cause producing them. And it is a curious proof of 

 that proneness to frame hypotheses, which philosophers of all ages and 

 countries have been so remarkable for, that the conversion of food 

 into chyme, in other words digestion, (so far as that process is com- 

 pleted in this organ) continued for a long time to be attributed, solely 

 to the trituration which the food was supposed to undergo, from 

 the mechanical action of the stomach. Several of our English 

 philosphers adopted this notion, and amongst others Dr. Pitcairn, 

 whom, as well as Dr. Mead, 1 consider as one of the fathers of the 

 mechanical philosophy, in the English school of Physic. 



Cheselden, however, an ingenious Surgeon, and acute reasoner, 

 long ago discovered, that the stomach exerted no such powers in the 

 way of mechanical action on food, as Dr. Pitcairn had attributed 

 to it, and successfully combated his reasonings on the subject,, 

 which, it is now well known, proceeded upon false premises. 



For, if food were convertible into chyme by the mere grinding 

 powers of the stomach, th^n it would follow as a matter of course, 

 that by subjecting moist food to mechanical trituration, out of the 

 body, at the same temperature that it is exposed to in the stomachy 



4B 



