INTESTINAL DIGESTION. 345 



saliva (the activity of which was stopped by the acidity of 

 the gastric juice) to recommence its action upon starch. 

 Moreover, in the stomach there is produced, alongside of the 

 true peptones, a body called parapeptone, which agrees very 

 closely with syntonin (p. 126) in its properties, and this 

 passes into the duodenum in the chyme. As soon as the 

 bile meets the chyme it precipitates the parapeptone, and 

 this carries down with it any peptones which, having es- 

 caped absorption in the stomach, may be present; it also 

 precipitates the pepsin. In consequence, one commonly 

 finds, during digestion, a sticky granular precipitate over 

 the villi, and in the folds between the valvulao conniventes 

 of the duodenum. This is soon redissolved by the pancre- 

 atic secretion, which also changes into peptones the pro- 

 teids (usually a considerable proportion of those eaten at a 

 meal) which have passed through the stomach unchanged, 

 or in the form of parapeptones. The conversion of starch 

 into grape sugar will go on rapidly under the influence of 

 the pancreatic secretion. Fats will be split up and saponi- 

 fied to a certain extent, but a far larger proportion will be 

 emulsified and give the chyle a whitish appearance. Cane 

 sugar, which may have escaped absorption in the stomach, 

 will be converted into grape sugar and absorbed, along with 

 any salines which may, also, have hitherto escaped. Elastic 

 tissue from animal substances eaten, cellulose from plants, 

 and mucin from the secretions of the alimentary tract, will 

 all remain unchanged. 



Absorption from the Small Intestine. The chyme leav- 

 ing the stomach is a semi-liquid mass which, being mixed 

 in the duodenum with considerable quantities of pancreatic 

 secretion and bile, is still further diluted. Thenceforth it 

 gets the intestinal secretion added to it but, the absorption 

 more than counterbalancing the addition of liquid, the foocl- 

 mass becomes more and more solid as it approaches the 

 ileo-colic valve. At the same time it becomes poorer in 

 nutritive constituents, these being gradually removed from 

 it in its progress; most dialyze through the epithelium into 

 the subjacent blood and lymphatic vessels, and are carried 

 off. Those passing into the blood capillaries are taken by 



