DIGESTIBILITY OF FOOD. 319 



an impeding action on the digestion of other substances in that 

 organ, since, on the one hand, it liquefies in consequence of the 

 high temperature, and, encasing as it were the individual particles 

 of food, renders them proof against the digestive juices ; and since, 

 on the other, it becomes rancid during its long retention at that 

 temperature, and forms volatile acids, which exert a very dele- 

 terious, although riot duly investigated, action on digestion. It 

 must, therefore, be admitted that large quantities of fat are pre- 

 judicial to gastric digestion, although, strictly speaking, there is no 

 digestion of fat in the stomach. The digestion of fat does not 

 commence, as we have already seen, until it reaches the small 

 intestine, and even there it only takes place under certain limita- 

 tions. We have seen from the accordant experiments of Bous- 

 singault on the one hand, and Bidder and Schmidt on the other, 

 that the animal organism can only take up a limited quantity of 

 fat in a given time ; after animals were fed upon very fat flesh, we 

 find that there were ejected from the fistulous opening in the 

 intestine (in Bidder and Schmidt's experiments) grey masses 

 which contained an abundance of fat, while only very slight 

 remains of muscular fibres could be detected in them. Hence 

 we can no more draw any inference from the retention of the fat 

 in the stomach regarding the degree of its digestibility than from 

 its passage into the small intestine and the solid excrements. 

 Small quantities of fat meet with the means requisite for their 

 digestion in the small intestine, and are there very rapidly 

 resorbed. If we can draw any conclusion from the distension of 

 the intestinal villi with fat, and the appearance of white chyle in 

 their lacteals, we must regard the fat as very easy of digestion ; for 

 in the course of from half an hour to an hour after fatty food or 

 oil has been taken, we find in the upper part of the jejunum in 

 dogs, cats, and rabbits (as I have very often convinced myself), 

 not merely the epithelium filled with fat-globules, but also the 

 lacteals with glistening white chyle. We have, however, formerly 

 shewn (see vol. i, p. 265) that fat, when not mixed in too large 

 quantity with the food, essentially promotes the digestion both of 

 the albuminous and the amylaceous substances. 



It has been already fully shown that most vegetable substances, 

 like the fats, do not undergo gastric digestion ; we cannot, there- 

 fore, judge regarding their digestibility from their longer or shorter 

 retention in the stomach, in the same manner as in the case of the 

 albuminous matters. We have already expressed an opinion, 

 founded on our own experiments, and differing from that of 



