ACTIVITY OF THE WALL OF THE ALIMENTARY CANAL. 357 



The experiments of Lenz, Bidder and Schmidt render it probable that the 

 organism can take up only a limited amount of fat within a certain time, and 

 this may, perhaps, bear a definite relation to the quantity of bile and pancreatic 

 juice. Beyond that amount no more fat is absorbed. Thus, in cats, 0.6 gram of 

 fat an hour was found to be the greatest amount absorbed for every kilogram 

 of body weight. I. Munk and Rosenstein found the absorption of fat greatest 

 from 5 to 8 hours after ingestion, and earlier or later accordingly as the fat was 

 more or less readily liquefiable. 



The greater part of the soaps in the intestine, transformed into 

 neutral fat, passes over into the chyle. It seems as if the soaps are 

 capable of uniting with glycerin in the parenchyma of the villus to form 

 neutral fat. Perewoznikoff and Will found neutral fat after the injection 

 of both of these ingredients into the intestinal canal, and also C. A. 

 Ewald observed fat to form when he brought soap and glycerin in contact 

 with the fresh, living intestinal mucous membrane. Blood and chyle 

 contain no free fatty acids. In the blood the fat is subsequently decom- 

 posed in the presence of oxygen. 



Of other organic matters in solution that are introduced into the intestinal 

 tract, some are absorbed, as, for example, alcohol, and many others. Other 

 bodies may be in part absorbed, in part fermented: tartaric acid, citric acid, malic 

 acid, lactic acid, glycerin and inulin ; gum and vegetable mucin, which give rise 

 to the formation of glycogen in the liver; and it is probable that unknown products 

 of metabolism are also absorbed. 



Of pigments, alizarin, alkanna and indigo-carmine are absorbed; others are 

 in part absorbed, such as hematin; chlorophyll is not absorbed. Metallic salts 

 appear, in part, to be held in solution by an excess of albuminates, and to be 

 absorbed at the same time with these (iron sulphate has been found in the chyle) , 

 and, in part, to be conveyed to the liver through the blood of the portal vein. 

 Numerous poisons undergo rapid absorption, prussic acid in the course of a few 

 seconds; potassium cyanid has been found in the chyle. 



Moreover, the purely physical conception of the absorption even of 

 true solutions by endosmosis and filtration alone is not sufficient. Here, 

 also, the protoplasm of the cells takes at least an active part, for only 

 in this way is it possible to explain how even a slight derangement in 

 the activity of these cells, as, for example, after cold or excitement, 

 may be followed by sudden serious disturbances of absorption, even the 

 escape of fluid into the intestine. Only in this way, also, can the fact 

 be explained that the presence of different spices, in small amount, 

 actively increases absorption in the stomach. If, further, absorption 

 took place solely and alone by endosmosis, water would pass over into 

 the intestine after the injection of alcohol; but this never occurs. 

 Further, salt is absorbed in the intestine from a solution that has less 

 osmotic energy than blood-plasma. Moreover, Brieger observed, after 

 the injection of from 0.5 to i per cent, solutions of metallic salts into 

 ligated loops of the intestine, that transudation of water into the bowel 

 failed to take place; although this occurred when injections of 20 per 

 cent, solutions were made. 



Absorption of the Smallest Granules. The largest amount of the 

 neutral fats and at the same time also of the fatty acids is absorbed in 

 the form of a milky emulsion prepared by the bile and by the pancreatic 

 juice and composed of minute granules. The individual fat-granules 

 appear to be surrounded by a delicate albuminous membrane, the hap- 

 togenic membrane, which is derived in part from the pancreatic juice. 

 In the absorption of fat-emulsions, the villi of the small intestine par- 

 ticipate primarily and in greatest degree; but the epithelial cells of the 



