ABSORPTION 373 



the proteids in the lymph flowing from a lymphatic fistula 

 in a case of elephantiasis in man were not found to be 

 sensibly increased during the digestion of proteid food 

 (Munk). 



Although a certain amount of egg-albumin, serum-albumin, 

 -alkali-albumin, and other native or slightly altered proteid 

 substances can be absorbed as such by the small, and even 

 by the large, intestine, there can be no doubt that the greater 

 part of the proteids of the food is first changed into proteoses 

 and peptones. But proteose and peptone are absent from 

 the blood, and, indeed, when injected into the blood they are 

 excreted in the urine. When injected in larger amount they 

 pass also into the lymph, from which they gradually reach 

 the blood again, and are eventually, as before, eliminated by 

 the kidneys. The clear inference is that when absorbed from 

 the alimentary canal they must be changed into one or both 

 of the chief proteids of blood and lymph (serum-albumin and 

 serum-globulin) in their passage through its walls. And it 

 has actually been shown that during the digestion of a pro- 

 teid meal the mucosa of the stomach and intestine contains 

 proteose and peptone, while none is present in the muscular 

 coat or in any other organ. They rapidly disappear from 

 a portion of the mucous membrane kept at a temperature 

 of about 40 C. outside of the body; but not if it has been 

 thrown into boiling water immediately after excision, nor 

 ven if it has been heated to 60 C. for a few minutes, and 

 then kept at 40 C. Now, a temperature of 60 C. does not 

 destroy an unorganised ferment, but kills a living cell. The 

 regeneration of the proteose and peptone must therefore pre- 

 sumably take place in cells, and the only available cells in 

 this locality are those which line the intestine, or the leuco- 

 cytes which wander between them. Accordingly, both have 

 been credited with the power of absorbing and transforming 

 these substances, but the balance of evidence is in favour of 

 the epithelial cells. We cannot, however, as in the case of 1 

 the fat, single out any particular tract of epithelium as alone 

 engaged in the absorption of proteose and peptone, or, 

 indeed, of the diffusible substances in general. In all likeli- 

 hood the cells covering the villi are actively concerned, but 



