Royal Society. 463 



of the bile and pancreatic ducts in the same animal, the digestion of 

 starch is still effected. 



10. The only remaining secretion is the intestinal mucus, which 

 is especially abundant at the upper part of the intestinal canal; and 

 a further proof is afforded of the activity of the intestinal mucus 

 taken from the upper part of the duodenum above the entrance of 

 the pancreatic duct after ligature of this duct and the common bile- 

 duct, by its capability of converting a large quantity of fresh boiled 

 starch into glucose out of the body. 



11. In the cooking of starch-containing vegetables, such as pota- 

 toes and peas, the adhesion of the starch-cells is dissolved or weak- 

 ened, so as to render them easily separable and amenable to the 

 action of the intestinal fluids. At the same time the starch-granules 

 undergo a large increase in bulk, distend the cells, and by their 

 mutual compression, their outlines present the appearance of gyrate 

 lines beneath the cell-wall. The cells seldom burst so as to emit 

 their contents, or present any appreciable opening through which 

 the intestinal fluids can directly penetrate. The author cannot 

 positively affirm so much of the starch-membranes, because these 

 are so extremely delicate that fissures might be invisible, but he 

 believes that in a great number the membranes remain entire. 



12. If this be the case, the conversion of starch matter into 

 glucose must be effected by the permeation or endosmose of the 

 intestinal fluids through the invisible pores of two membranes, 

 in the digestion of the pea, the potato, and other similar foods, 

 and the glucose must escape through the same membranes by 

 exosmose. 



13. Before the conversion of starch into glucose, the amylaceous 

 matter contained in the starch is more dense than the intestinal 

 mucus in immediate contact with the cells, and an inward current 

 or endosmose is established ; but after that conversion, the syrupy 

 fluid is less dense than the mucus, and then an outward current or 

 exosmose occurs, by which the glucose escapes from the cells into 

 the intestine and is absorbed. If this be the case, as the details of 

 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 be 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 



