NORMAL FAT METABOLISM 191 



histologically and chemically, and confirmed in general the work of Greene 

 and Skaer, although in some animals they found no penetration. They 

 found no change in the fat content of the blood as a result of the presence 

 of fat in the stomach, but they point out that the absorption would be 

 necessarily slow and that the fat may have been removed from the blood 

 as fast as absorbed. That absorption of other substances went on normally 

 in these same animals was shown by tests with iodids. On feeding fat 

 stained with Sudan III no color could be observed in the lymph or in 

 the blood. 



The Intestines. Passage from the Stomach. When the amount 

 of fat in the food is small it probably does not affect appreciably the rate 

 >f emptying of the stomach, which proceeds normally as described by 

 Cannon the pylorus opening under the stimulus of a sufficient acidity 

 of the food on the gastric side and closing when the acid food 

 reaches the intestinal side of the opening valve. When the amount of fat 

 in the food is large the gastric secretion is inhibited, the amount of acid 

 produced is lessened, and it therefore takes longer for the food to reach the 

 degree of acidity necessary to bring about the opening of the pylorus. 

 The rate of emptying of the stomach is thus slowed and the rate at which 

 the fat reaches the intestine is lowered. When, however, the fat is taken 

 in liquid form (as oil) or suspended in a liquid, as in milk, it may pass 

 immediately through the stomach like other liquids. 



Thus in all cases except where the fat is taken in quantity in the form 

 of oil (an unusual condition) it is passed into the intestine in small por- 

 tions. When it reaches the intestine in large quantities diarrhea may be 

 produced either through action of the fat itself or more probably as the 

 result of irritation produced by the abnormally large amounts of soaps 

 formed. One result of the normal functioning of the gastric mechanism 

 is therefore the delivery of the fats to the intestine in small amounts, which 

 has a direct bearing on the question as to the form in which it is absorbed 

 from the intestine, since under these circumstances the chances are that 

 the fat will be completely hydrolyzed in the presence of the relatively 

 large amounts of pancreatic and intestinal lipases which it encounters. 

 When the amount of fat in the food is so large that there is great in- 

 hibition of gastric secretion the pylorus appears to lose its tone after some 

 hours and allows the passage of intestinal contents bile and pancreatic 

 secretion with its lipase to pass into the stomach, where considerable 

 hydrolysis of the fats may take place. Boldireff has shown that this re- 

 giirgitation may be made to take place readily in humans by feeding 

 fat containing fatty acid. 



Xatural food fat always contains some free fatty acid and the amount 

 is increased during the processes of cooking and by whatever lipolytic 

 action occurs in the stomach, so that by the time the fat reaches the 

 intestine there is probably always a considerable quantity of free fatty 



