72 PROTEIN DIGESTION IN THE INTESTINE 



This done, we may well hope that from these studies and 

 others dealing with related matters (of which special men- 

 tion may be made in passing of those of Cohnheim, 63 



E. Zunz, 64 Brugsch, 65 A. Scheunert, 66 and K. Glassner 67 ) 

 a well rounded picture of protein dissociation in the intestine 

 in each of its phases will gradually take shape. 68 



Summary. If in conclusion another glance be cast back 

 over the long way behind us, it will be realized that as the 

 actual accomplishment of an almost interminable expendi- 

 ture of effort and experimental work we may say that we 

 know that ~by the combined action of pepsin, trypsin and erep- 

 sin the protein in the alimentary canal can be effectively split 

 into its most simple structural units and that a mixture of 

 these constituent fragments is not only qualitatively but quan- 

 titatively in every sense equivalent to the protein as supplied 

 intact. To be able to say that means something, but by 

 no means all. Abderhalden says very properly "that up 

 to this time it is entirely impossible from examination of the 

 intestinal contents to draw exact conclusions as to the degree 

 of catabolism of the food, because besides the products of 

 complete cleavage we must take into consideration also the 

 intermediate substances." He states explicitly, too, "from 

 our finding that a combined mixture of amino acids is capable 

 of fully maintaining protein metabolism for weeks and 

 months we cannot conclude at once that necessarily in 



63 R. Baumstark and O. Cohnheim ( Physiol. Instit., Heidelberg ) , Zeitschr. 

 f. physiol. Chem., 65, 477, 483, 1910. 



*E. Zunz, Bulletin de 1'Acad. Roy. de He'd, de Belgique, 30, April, 1910; 

 cf. here Literature and review of author's numerous earlier contributions in 

 same connection. 



65 Th. Brugsch, Zeitschr. f. exper. Pathol., 6, 326, 1909. 



66 A. Scheunert, Pfluger's Arch., 121, 169, 1908; 139, 131, 1911; 1^1, 

 411, 1911. 



6T K. Glassner (F. Kraus' Clinic, Berlin), Zeitschr. f. klin. Med., 52, 361, 

 1904. 



68 Cf. also V. Lieblein (Prague), Zeitschr. f. Heilk., Abt. f. Chirurgie, 1906; 



F. Keller, Inaug. Diss., Breslau, 1909, abstract in Centralbl. f. Physiol., 23, 

 616, 1909. 



