ALIMENTARY TRACT AS AN ABSORPTIVE SYSTEM. 305 



testine appear to be caught and held by some organ, such as 

 the liver or spleen, before passing over into the general cir- 

 culation. This has been shown by comparative analyses of 

 the blood obtained from the portal vein, for example, and 

 that obtained from a large artery, as well as by the experi- 

 ments already cited. 



What, then, does become of the proteins which enter the 

 alimentary tract? It is clear that if they disappear from the 

 lumen of the intestine and cannot be discovered in the blood 

 leaving the alimentary tract as proteoses and peptones they 

 must exist here in some other form. In what form cannot 

 be easily said, though there are two possibilities, either or 

 both of which may be correct, and both of which have ex- 

 perimental foundation. 



The first of these is that the proteins, be these absorbed in 

 whatever way we may consider the correct one, are recon- 

 structed in their passage through the epithelium of the 

 stomach or intestine into complex albumins and globu- 

 lins which we are unable to distinguish from those found 

 normally in the blood. This means that if we believe all 

 the protein of a meal to be absorbed in the form of KUHNE'S 

 peptones, or perhaps in the form of mono- and diamino- 

 acids, that these are reconverted into complex albumins in 

 passing through the alimentary wall. 



The experiments of ABDERHALDEN and SAMUELY l are of 

 great interest in this connection. These show that the com- 

 position of the blood, so far as its protein constituents are 

 concerned, is apparently entirely independent of the char- 

 acter of the proteins consumed by the individual. Analysis 

 of six litres of blood removed from the veins of a horse showed 

 that it contained protein bodies which yielded after hydrol- 

 ysis : 



Tyrosin 2 . 43 percent 



Glutamic acid 8.85 " 



l . ABDERHALDEN and SAMUELY: Zeitschr, f. physiol, Chem., 1C05, 

 XLVI,p.l93. 



