250 PROCEEDINGS OF SOCIETIES. 



3. The conversion of boiled starch into dextrine and glucose is 

 chiefly effected in the first few inches of the small intestine, but it 

 continues to take place in a less degree throughout the entire intes- 

 tinal canal. 



4. In the digestion of boiled wheat or other starch, or of wheaten 

 bread, the bulk of the mass rapidly diminishes in its passage through 

 the small and large intestines, so that it ultimately yields only a 

 small quantity of fsecal matter. After being deprived of their con- 

 tents, the membranes of the granules shrink and shrivel up into a 

 minute granular matter, which constitutes the chief bulk of the 

 feecal evacuations after an exclusive diet of starch food. 



5. The digestion of raw starch food (peas) in the pigeon or other 

 granivorous birds goes on much more slowly, and progresses pretty 

 equally throughout the entire intestinal canal. The starch-granules, 

 whether free or included in cells, become intersected by radiating or 

 irregular lines or fissures, more or less opaque or granular ; they 

 also gradually lose their characteristic reaction with iodine ; and 

 this important change, commencing at the surface, progresses 

 towards the centre, until the whole of the starch matter is removed, 

 leaving the starch-membranes often apparently whole, retaining 

 their characteristic markings. The fissured and granular condition 

 of the starch-granules is not due to their trituration in the gizzard, 

 but to the action of the intestinal fluids, since it was often seen in 

 granules enclosed in and protected by perfect starch-cells. In the 

 digestion of raw starch food, a consideral)le quantity always escapes 

 change, for many starch-cells and granules in the faeces perfectly 

 retain the characteristic reaction with iodine. 



6. As the starch remains unchanged in the stomach, its conver- 

 sion into glucose cannot be attributed to the saliva or gastric juice, 

 unless we suppose these fluids to remain inactive in the stomach, 

 and suddenly to regain their activity in the first part of the small 

 intestine. The author found that the saliva was capable of effecting 

 the conversion of starch into glucose, but that the mixture of saliva 

 and gastric juice in the stomach did not possess that property even 

 after being rendered alkaline by carbonate of soda. It is probable 

 that the converting power of the saliva, as it flows from the mouth, 

 depends not on the true saliva, but on the buccal mucus ; for Ma- 

 gendie found that saliva taken from the parotid duct was wholly in- 

 active, while the mixed saliva from the mouth effected the conversion 

 with great f icility. Unless, then, the sublingual and submaxilliary 

 glands secrete a different fluid from the parotids, it is evident that the 

 activity of the saliva must be attributed to the buccal mucus. 



7. The difference between the digestion of boiled and raw starch 

 in dogs is seen in the experiments on the digestion of boiled wheat- 

 starch, boiled tous les mois, and bread. In all these, some starch- 

 granules escape the action of heat and water, and remain in nearly 

 their pristine condition. These uncooked starch-granules undergo 

 slow and imperfect changes, being fissured, broken, and more or less 

 altered, but, in general, retaining their characteristic reaction with 

 iodine. 



8. The conversion of starch into glucose is not effected by the 



