DIGESTION OF THE ALBUMINS. 173 



of certain albumins, such as the syntonins, obtained from myosin, 

 fibrin, etc., does not lead to their elimination in the urine, and as the 

 blood manifests a very strong tendency to maintain its composition 

 uniform, it has been argued that these albumins are probably re- 

 tained in some organ of the body, such as the liver, and may here 

 be transformed into material which can be utilized for purposes of 

 nutrition. Such an assumption seems to me entirely unwarrantable, 

 however, as it is solely based upon the non-appearance of these 

 albumins in the urine in the state in which they were introduced. 

 Egg-albumin, it is true, is immediately eliminated under such con- 

 ditions, and it might be concluded that the kidneys could also 

 eliminate those other forms, if the body were incapable of utiliz- 

 ing them as such. This, however, does not follow, for we know 

 that the introduction of egg-albumin in large amounts into the 

 stomach leads to its appearance in the blood as such, so that the 

 conditions here are reversed ; but it would be manifestly inadmis- 

 sible to conclude from this observation that because egg-albumin 

 can pass the epithelial barrier, as such, it cannot be utilized within 

 the body itself or cannot be digested in the stomach and intestines. 

 That the introduction of such albumins which are normally present 

 in the blood does not lead to albuminuria is, of course, not sur- 

 prising ; but to conclude that syntonin can be utilized by the body 

 directly because it is not eliminated in the urine in the same form 

 is, as I have said, unjustifiable. 



On the other hand, we must admit that the resorption of native 

 albumin can occur in the absence of the proteolytic ferments, and it 

 is more than probable that during this resorption the epithelial cells 

 bring about a rearrangement of the atomic groups of the albu- 

 minous molecule, so that the ultimate result is the same as though 

 the hydrolytic decomposition had proceeded further under the influ- 

 ence of the ferments and resorption had then occurred. Of the 

 extent to which epithelial activity enters into the process of diges- 

 tion, however, we know nothing, but it is likely that under normal 

 conditions fermentative digestion prevails, and that the function of 

 the epithelial cells, principally consists in transforming the albumins 

 and peptones into material which can be utilized by the body for 

 purposes of nutrition. That this transformation actually takes 

 place within the epithelial cells which line the gastro-intestinal 

 mucosa is now established beyond a doubt. Formerly it was sup- 

 posed that this change occurred within the liver, especially as 

 neither albumoses nor peptones can normally be found in the periph- 

 eral circulation. But this-has since been disproved in many ways. It 

 has thus been found that in animals which are killed by bleeding from 

 the portal vein at a time when peptones are abundantly present in 

 the intestines no peptones can be found in the blood. Whenever 

 peptones are introduced into the blood artificially, or whenever they 

 are formed beyond the intestinal mucous membrane, as under certain 

 pathologic conditions, they are invariably eliminated in the urine as 



