52 PROTEIN DIGESTION IN THE INTESTINE 



There can be no objection to regarding erepsin in the light of 

 a "heterolytic" ferment, however, even if it be not an 

 "autolytic" one. 



From such considerations it is evident that nature has 

 fully provided means to insure the splitting of the proteid 

 constituents of the food into their end-products. We are in 

 position, therefore, to proceed a step further and take up the 

 question whether there is any evidence that the provision can 

 be traced as actually operative in normal digestion in further 

 measure. 6 



Extent of Protein Dissociation in the Intestine. The 

 classical investigation by Carl Ludwig and Salvioli should 

 be recalled showing that peptone solution may disappear 

 from the lumen of a loop of the small intestine (artificially 

 perfused with blood) without peptone becoming demon- 

 strable in the blood used in perfusion. Later, in 1881, Franz 

 Hofmeister, whose pupil the author was, demonstrated the 

 disappearance of peptone when brought in contact with 

 gastric mucosa in extracorporeal conditions ; and N. Neu- 

 meister made a similar demonstration for the intestinal 

 mucosa. The interpretation of these fundamental and 

 amply corroborated observations suggesting a resorption 

 process, at a later date was modified by the discovery, 

 mainly due -to work by Kutscher and Seemann, Cohnheim, 

 Cathcart and Leathes, 7 that, while albumoses and peptones 

 disappear when brought in contact outside the body with 

 intestinal mucosa, this is due not to their resorption but to 

 their dissociation into more simple protein derivatives. 



Moreover, the investigations of these authors, and chiefly 



'Literature upon the Extent of Protein Dissociation in the Intestine: 

 J. Munk, Ergebn. d. Physiol., 1, 310-317, 1902; 0. Cohnheim, Nagel's Handb. d. 

 Physiol., 2, 629, 1907; H. Liithje, Ergebn. d. Physiol., 7, 800-804, 1908; 0. 

 Prym, Handb. d. Biochem., 8", 102, 1909; W. Biedermann, Winterstein's 

 Handb. d. vergl. Physiol., 2", 1448-1449, 1911. 



T F. Kutscher and J. Seemann, Zeitschr. f . physiol. Chem., 84, 528, 1902 ; 

 35, 432, 1902; 49, 298, 1907; O. Cohnheim, ibid., 38, 451, 1901; 36, 13, 1902; 

 49, 64, 1906; 51, 415, 1907; E. P. Cathcart and J. B. Leathes, Journ. of 

 Physiol., 33, 462, 1905. 



