200 THE FLUIDS. 



ready explained. The gastric favuli, into which these glands open, 

 are shown by Fig. 111. 



Function. It is by the agency of the gastric fluid that the albu- 

 minous compounds in the food are dissolved 1 and converted into 

 uncoagulable substances, soluble in water and dilute alcohol, and 

 which Lehmann has termed peptones. Mialhe first termed these 

 substances albuminose (p. 87). It is probable that the acids are 

 principally efficient in dissolving these compounds ; while the pep- 

 sin, acting by catalysis, enables them to exert a vastly greater sol- 

 vent power than they would without it. From 3 to 5 grains of 

 coagulated albumen may be dissolved in 100 grains of recent gas- 

 tric juice. It has no effect at all on the fats and other non-nitro- 

 genized elements of the food, these passing through the stomach 

 unchanged by it. Other strong mineral acids (but not the organic) 

 may partially supply the place of the hydrochloric and lactic. Its 

 digestive power is also increased by the addition of fat. Bile en- 

 tirely suspends its digestive power, and saliva diminishes it. 



The gastric fluid, however, is not sufficient to dissolve all the 

 albuminous compounds necessary to nourish an animal. 2 (Lehmann.) 

 Besides, it loses its digestive power in the duodenum, where its acid 

 reaction is overcome by the alkaline bile and pancreatic fluid. 

 Another fluid must therefore flow into the intestine, below the 

 duodenum, which exerts a similar effect, and which will be next 

 described. 



The Intestinal Fluid. 



Frerichs has ascertained that the glandulae aggregatse (Peyer's 

 patches) contribute but very slightly 3 to the formation of the intes- 

 tinal fluid they being closed sacs and that its true secreting or- 

 gans are the pouch-like follicles of the small intestine (Lieberkuhn's 

 follicles), and the similar larger and very numerous follicles of trie 

 large intestine. In chemical composition, the fluids of the small 

 and the large intestine are found to be perfectly identical. GV-fc'&n 



The intestinal fluid is a glassy, transparent, colorless, tenacious 



1 Bernard proves that while white fibrous tissue is dissolved, muscular fibre is 

 merely softened, as if it had been boiled. Starch, sugar, and fat are not affected 

 at all by the gastric fluid. 



2 This assertion is doubtless correct in itself, but not at all consistent with Leh- 

 mann's estimate of its quantity, mentioned on page 199. 



3 Not in the least, as will appear in the chapter on "The Alimentary Canal." 



