196 W. It. BLOCK 



Synthesis of the Fats During Absorption. It is a necessary corollary 

 of the foregoing that the splitting of the fats which takes place in the 

 intestine is follower! by a resynthesis before the fat reaches the thoracic 

 duct. Direct proof of the synthesis has, however, not been satisfactorily 

 furnished. Ewald thought that he had demon st rated a synthesis by the 

 surviving intestinal mucous membrane, as did also Hamburger, but Frank 

 and Hitter, on repetition of their experiments, were unable to get posi- 

 tive results, and pointed out that their results were irregular and that 

 such positive findings as were obtained were due to faulty technique. Sim- 

 ilarly Moore failed to demonstrate synthesis in vitro using mixtures of 

 sodium oleate and glycerol with hashed intestinal mucous membrane. 

 On the other hand, Moore showed that during fat absorption the fatty 

 acid in the mucous membrane of the intestine amounted to 15-35 per 

 cent of the total fat, while in the mesenterial glands and lymph vessels 

 it amounted to only about 4 per cent, which facts they believed to show 

 that the synthesis took place in the mucous membrane and not in the 

 lymph glands. 



Paths- of Absorption of Fat. The thoracic duct is probably not the 

 only channel by which fat reaches the blood stream. Mimk and Kosenstein 

 in chyle fistula experiments with a human being were able to recover not 

 more than 60 per cent of the total fat fed. In experiments with dogs 

 Munk and Friedenthal were able to show an absorption of 32 to 48 per 

 cent of the fat fed after tying off all the neck and arm veins of both 

 sides. The blood fat increased from 0.5 per cent to 2.92 per cent, with 

 notable increases of fat in the corpuscles. Others have found, on the 

 contrary, that tying off the thoracic duct prevented any increase in blood 

 fat. Munk also noted the accumulation of fat droplets in the liver during 

 normal fat absorption ("physiological fat infiltration"), which he be- 

 lieved to originate from fat directly absorbed into the portal vein 

 although it could equally well be ascribed to fat which had reached the 

 blood stream by the thoracic duct. v. Walther found in the chyle not 

 more than 1/10 of the fat which had disappeared from the intestine of 

 dogs. A similar observation is reported by Frank (1808). Attention should 

 be directed to the fact that in these thoracic duct experiments the operative 

 procedure is severe and the results found may not represent what happens 

 normally. Aside from the thoracic duct there is left the path of absorption 

 taken by other foodstuffs, i. e., directly into the circulation by the intestinal 

 capillaries and the portal vein, but there is very little direct evidence of 

 absorption by this channel. D'Errico showed that during fat absorption 

 the fat content of the portal vein was always higher than of the jugular and 

 concluded that fat was normally absorbed directly into the circulation like 

 other food substances. Very recently Zucker has reported negatively on 

 repetition of this work. 



Changes in Fats During Absorption. In spite of the fact that large 



