vi] Sylvius and his Pupils. 165 



older view that the stomach was the chief seat of digestion, and 

 that bile either served in some way as an aid to gastric digestion, 

 or was merely an excrement. 



Concerning gastric digestion itself, two views contended for 

 prominence. Borelli, with his mind directed chiefly to me- 

 chanical effects, had pointed out the great grinding, crushing 

 force which was provided for by the muscular coats of the 

 stomach. He calls attention to the fact " that in birds with 

 " few exceptions the crushing, erosion and trituration of food is 

 " effected by the muscular stomach itself, compressing one part 

 " of its horny lining against another. Thus with the help of 

 "small hard and sharp pebbles contained in it, which serve 

 " instead of teeth, the stomach by pounding the food swallowed 

 "and rubbing its inner surfaces on it this way and that, like 

 "millstones, crushes the parts of the food until they are con- 

 " verted into a very fine powder. This at Pisa, at the bidding 

 "of. his Serene Highness Duke Ferdinand II., I ascertained by 

 " experiment to be quite true. For I introduced by the mouth 

 " into the stomach of turkeys, glass globules, or empty vesicles, 

 "and leaden cubes, similarly hollowed out, pyramids of wood 

 " and many other things, and the next day I found the leaden 

 " masses crushed and eroded, the glass pulverized and the 

 " remaining ingesta in the same condition." 



He admits however that birds of prey and fishes which are 

 destitute of teeth and possess not a fleshy but a membranous 

 stomach like that of a quadruped, digest their hard food in a 

 different manner. "These animals consume flesh and bones by 

 " means of a certain very potent ferment much in the same 

 " way as corrosive liquids corrode and dissolve metals. Such a 

 " corrosive juice is poured forth by the small glands with which 

 " the membranous substance of the stomach is crowded, as 

 " I have most clearly seen in the stomach of the Dolphin, in 

 " which the small glands are very stout and prominent." 



Quantitative as he always was he desired to estimate the 

 exact force of these muscles of the stomach, and he proceeded 

 on the same plan as that which he had adopted for determining 

 the force of the heart systole. 



" Having noticed that some filberts possess a shell so hard 



