igoi] Charron — Fat in the Animal Body, 135 



is that none of the fats are stored up in the body without previous 

 decomposition. After the fatty material is introduced into the 

 alimentary canal, the first liquid it meets on its way is the acid 

 g-astric juice which, as far as we know, has no effect whatever upon 

 it. This juice has the carbohydrates and the proteids to contend 

 with and enough has it to do. The fat, therefore, passes unheeded, 

 but a little further it meets its most bitter enemy, namely, the 

 alkaline pancreatic juice which wrestles with it until its entire 

 decomposition is effected. By its action the fat is resolved into 

 glycerine and a salt of the fatty acids, which salt is known as a 

 soap. 



Now as you well know soaps are usually soluble. Tliis one 

 is very similar to that so often called into domestic use and like it 

 is soluble. It dissolves and is readily absorbed by the numerous 

 villi, capillary filaments linings the small intestine, whose functions 

 consist in absorbing the thus dissolved foods. In this way the 

 soap is introduced into the circulating system and carried to the 

 epithelium cells where it in turn suffers decomposition into its 

 org-anic acid and an alkali. The organic acid again unites with 

 the glycerine which has been absorbed at the same time as the 

 soap and the fat is reformed. 



The fact that the fat of an animal fed entirely on a certain 

 kind of fat is not identical in composition with the fat fed, seems 

 to indicate this double decomposition and a certain power of selec- 

 tion on the part of the little villi foraging for their proper food. 

 Undoubtedly if an exclusive diet of a certain fat is given some of 

 the reformed fat will inevitably be of the same composition as the 

 one fed. 



The g-reat objection to the absorption of fat in the form of 

 soaps has been that the reaction ot the fluid in the small intestine 

 where the absorption takes place is not alkaline but acid, and 

 that a soap cannot persist in the presence of an acid liquid. Carb 

 investig-ated the reaction of the intestine in three experiments on 

 dogs, and found the intestinal contents to be acid all the way from 

 pylorus to caecum. The indicators used were litmus and phenol- 

 phtalein. Moore and Rockwood have recently studied the reaction 

 of the intestine making use, besides the indicators mentioned, of 

 methyl orange, which is not affected by carbonic and weak organic 



