231 



the experiments tend strongly to prove, a new and important func- 

 tion is assigned to the intestinal mucus. 



14. In normal digestion, chyme escapes very slowly from the 

 stomach into the duodenum, in small quantities, as it is detached 

 from the alimentary mass by the muscular movements of the stomach, 

 and this gradual propulsion often occupies several hours after a meal. 

 This slow propulsion is evidently intended to expose the commi- 

 nuted food fully to the action of the intestinal juices, and produce 

 an intimate mixture with them. The comparatively empty condi- 

 tion of the upper part of the small intestine, even during active 

 digestion, is thus fully explained. 



15. If the food he too finely divided or incapable of a second 

 solidification in the stomach, it passes too rapidly into the first part 

 of the small intestine, is insufficiently mixed with the intestinal 

 fluids, and a considerable part escapes digestion. On the other 

 hand, if it enters the small intestine in masses incapable of reduction 

 by the muscular action of the parts or solution in the fluid, it tra- 

 verses the intestinal canal unchanged, except at the surface, which 

 is then alone exposed to the action of the intestinal fluids. 



16. It is not necessary for the conversion of starch into glucose 

 that the fluids in the duodenum or other parts of the intestinal 

 canal should be alkaline, or even neutral, for in several of the expe- 

 riments the contents of every part of the alimentary canal had an 

 acid reaction. 



17. The greater part of the intestinal mucus is not excremen- 

 titious, for little, if any, mucus is perceptible in the faeces in normal 

 digestion, except at their surface, whereas the greater proportion of 

 the contents of the small intestine consists of mucus. A consider- 

 able quantity of mucus is seen in the caecum, but it rapidly dimi- 

 nishes in the colon, and is scarcely detectible in the faeces, except 

 that on the surface, which is probably derived from the mucous 

 membrane of the rectum. The author raises the question, whether 

 one of the chief functions of the caecum is not to effect the conver- 

 sion of the intestinal mucus into some other substance capable of 

 re-entering the blood, and performing some ulterior purpose in the 

 animal economy. 



18. In normal digestion, the separation of the epithelium of the 

 mucous membrane of the intestine is the exception instead of the rule, 



