THE LEUCOCYTES IN ORGANIC FUNCTIONS. 691 



the peptones are elaborated must be accounted for. Metchni- 

 koff traces these to products of degeneration, as suggested by 

 his comparison, and perhaps to waste-products of digestion. 

 Hofmeister's conception differs only from this in implying a 

 closer or more direct relationship between the leucocytes and 

 the intestinal contents of their host. In other words, while 

 Hofmeister associates leucocytes with the process of digestion, 

 Metchnikoff looks upon them only in the light of scavengers. 

 That phagocytes may fulfill both roles is obviously suggested, 

 not only by their own chemico-physiological characteristics, 

 but also by their itinerary in the system. Both Hofmeister 

 and Metchnikoff are right, therefore, each in his own way. 



In his review of the absorption of proteids Stewart 22 

 writes: "Although a certain amount of egg-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 peptones are absent from the blood, and, indeed, when in- 

 jected 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 

 digestion of a proteid 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 dis- 

 appear from a portion of the mucous membrane kept at a tem- 

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

 been thrown into boiling water immediately after excision, nor 

 even if it has been heated at 60 C. for a few minutes and then 

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

 an unorganized ferment, but kills a living cell. The regenera- 

 tion of the proteose and peptone must, therefore, presumably 



22 Stewart: "Manual of Physiology," fourth edition, 1900. 



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