ABSORPTION OF PROTEID 305 



filled spaces incompletely separated from one another by the connective-tissue 

 trabeculse of the stroma. 



It has long been known that fat, for the most part, passes into the lacteals 

 and is conveyed thence to the thoracic duct. Recent experiments have shown, 

 however, that no small part of it passes also into the blood vessels of the 

 intestine. In the case of the above-mentioned patient with a fistula in the 

 receptaculum chyli, only about sixty per cent of the absorbed fat, and still 

 less when free fatty acids were fed, was found in the chyle. Some forty 

 per cent, therefore, had taken the .pathway through the portal vein. 



Besides the fatty substances absorbed from the food, other fats pass into the 

 chyle, which have their origin in the intestine and its fluids. In this way, pos- 

 sibly, we may explain the fact that after feeding a fat of high melting point 

 the mixture of fat in the chyle melts at the temperature of the body i. e., that 

 in the transition from intestine to chyle a lowering of the melting point has 

 taken place. 



When soaps are injected directly into the blood, they produce symptoms of 

 weakened heart activity, the respiratory exchange of gases declines, the coagula- 

 bility of the blood is abolished, and, with a dose of only 0.1 g. oleic acid per 

 kilogram of body weight, rabbits are killed (I. Munk). The cause of these phe- 

 nomena, according to Friedlander, lies in the fact that the calcium of the blood 

 is precipitated by the fatty acids. 



4. ABSORPTION OF PROTEID 



If the digestive enzymes continue to act long enough, the proteids are 

 finally decomposed into simple crystallizable end products. To what extent 

 this cleavage takes place in normal digestion, i. e., whether the proteid sub- 

 stances are taken up chiefly as albumoses or as crystalline end products, we 

 cannot say definitely at present. It is possible, as some authors assume, mainly 

 on the ground of the action of erepsin, that the cleavage of proteid, either in 

 the intestine or in the mucous membrane, extends all the way to the final end 

 products; but it is conceivable also that the albumoses, as soon as they are 

 formed, are taken up from the intestinal cavity, and are not further decom- 

 posed in the mucous membrane. 



The experiments of Voit and Bauer have shown that even native proteids in 

 solution can be absorbed from the intestine without previous digestion. As much 

 as fifty-eight per cent of egg albumin placed in a loop, isolated from the rest of 

 the intestine, disappeared within five and one-half hours; twenty-eight per cent 

 of blood serum in the course of one hour; etc. This however constitutes no 

 proof that the first products would be absorbed in the course of normal digestion. 



If blood be passed through the vessels of a surviving intestine, in whose 

 cavity a peptone solution is contained, the peptone is absorbed but none of it 

 can be demonstrated in the blood. From this, and from the fact fhat after 

 a meal rich in proteid, the blood of the portal vein contained no more albu- 

 mose than the blood of the carotid, it was concluded that the absorbed products 

 of proteid digestion were changed in the mucosa to proteids of the same kind 

 as those occurring in the blood. 



