192 THE PROCESSES OF DIGESTION AND RESOEPTION. 



tained. Embden and Knoop maintain that this is possible, and 

 Langstein has shown that one or more albumoses can actually be 

 demonstrated in the blood. Further investigations in this direction, 

 however, are necessary before any definite conclusions can be 

 reached. 



The observation that albumins when introduced into the blood- 

 current directly can be utilized to a very great extent cannot be 

 surprising in the case of those albumins which are normally found 

 here. But Oppenheimer has shown that this also occurs to a certain 

 extent in the case of albumins which are foreign to the animal body, 

 such as egg-albumin. When introduced beyond a certain amount, 

 however, such albumins are eliminated in the urine ; but very curi- 

 ously the power of retaining egg-albumin, for example, can be greatly 

 increased by frequently repeated hypodermic or intravenous injec- 

 tions. 



In connection with the question regarding the reconstruction of 

 the albuminous molecule, certain observations made by Russian 

 writers especially deserve consideration. Danilewsky has thus 

 shown that it is possible by means of chymosin to produce precipi- 

 tates in concentrated solutions of albumoses, and Okunew could 

 demonstrate that this action is referable to the chymosin itself and 

 not to any other contaminating ferment. It was further shown 

 that both proto- and hetero-albumose are affected by the chymosin 

 and not the deutero-albumoses. The resulting products Sawjalow 

 has termed plaste'ins, and he regards these as albumins sui generis. 

 Later Kurajeff showed that papayotin has a similar action, but 

 that the secondary albumoses represent the most appropriate 

 material from which papayotin-plastein can be prepared. On 

 peptic or papayotin digestion this product again yields secondary 

 albumoses. 



Preceding Cohnheim's investigations, these experiments were 

 interpreted as indicating the manner in which the reconstruction of 

 the albuminous molecule might possibly occur in the intestinal 

 mucosa. In the light of Cohnheim's discovery of erepsin, however, 

 this construction falls away. 



THE DIGESTION OF FATS. 



The important role of the pancreas in the digestion of fats is 

 apparent from the experiments of Minkowski and Abelmann, who 

 could show that following extirpation of the pancreas in dogs the 

 absorption of fats ceases altogether, with the exception of butter- 

 fat, of which from 28 to 53 per cent, can still be utilized. Other 

 observers have obtained results which differ somewhat from those 

 of Minkowski ; but in all investigations it could at least be demon- 

 strated that in the absence of the pancreatic juice the absorption of 

 fats is impeded. This is due to the absence of lipase (steapsin). 

 Under normal conditions the lipase of the pancreatic juice causes 



