54 PROTEIN DIGESTION IN THE INTESTINE 



tant part of the protein dissociation-derivatives as under- 

 stood in the older conceptions may take place in the stage 

 of "albumoses" and " peptones. ' y If, however, this be not 

 the case, and if the dissociation proceeds to the extent of 

 producing crystallizable products, two further possibilities 

 present themselves: either these crystallizable derivatives 

 are absorbed as such, or they undergo a synthetic change, 

 before entering the blood, into high-molecular protein 

 derivatives in the intestinal wall. 



Passage of True Proteins and High-molecular Protein- 

 derivatives into the Blood. In considering the first of these 

 possibilities it must be granted that under certain circum- 

 stances high-molecular protein dissociation-products and, 

 too, true proteins, can pass from the bowel into the blood. 13 

 The precipitin reaction and anaphy lactic methods assure us 

 of the possibility of determining, with precision hitherto un- 

 dreamed of, the most minute quantities of foreign proteins in 

 the blood. 14 We know today that it is possible under given 

 conditions to determine by such methods proteid substances 

 absorbed from the bowel, as, for example, after flooding the 

 intestine with uncooked eggs, raw milk or blood-serum. The 

 normal protective influence of the intestinal epithelium is ap- 

 parently undeveloped in the newly-born; and, too, may be 

 decidedly impaired by pathological processes. 15 It may be 

 shown experimentally in vitro, too, that foreign serum, toxins, 

 haemolysins, ferments and antiferments of various kinds 

 diffuse more rapidly through an inflamed intestinal wall 

 than through the normal wall of the bowel; this perhaps 



"Literature upon Absorption of True Proteins and High Molecular 

 Protein Dissociation-products from the Bowel: 0. Cohnheim, Nagel's Handb. 

 d. Physiol., 2, 624, 1907; H. Liithje, Ergebn. d. Physiol., 7, 830-835, 1908; 

 C. Oppenheimer and L. Pincussohn, Handb. d. Biochem., 4', 705, 1911; P. Nolf, 

 Journ. de Physiol., Nov., 1907. 



14 F. Micheli (Turin), Giorn. Accad. Med. Torino, 73, 205, 1910. 



18 Ganghof ner and J. Langer (Prague), Miinchener med. Wochenschr., 51, 

 1497, 1904. 



