ABSORPTION OF PROTEINS. 525 



Before we can answer the question as to the form in which the pro- 

 teins are absorbed from the intestinal canal, it is of interest to learn 

 whether the animal body can, perhaps, also utilize such proteins as are 

 introduced intravenously, subcutaneously, or into a body-cavity, i.e., 

 evading the intestinal canal, or, as it is called parenteral. 



Since the first investigations of ZTJNTZ and v. MERING on this sub- 

 ject, several experimenters l have shown, without any doubt, that the 

 animal body can more or less completely utilize different, parenterally 

 introduced proteins, although different varieties of animals show a differ- 

 ence in this regard. Still we do not know where and how these foreign 

 proteins are changed and assimilated, but CRAMER ascribes great impor- 

 tance to the leucocytes in this regard. See ABDERHALDEN'S experiment 

 given on page 54. 



That the animal body can also assimilate not previously digested 

 or split proteins introduced directly into the intestine has been shown 

 by BRUCKE, BAUER and VOIT, EICHHORST, CZERNY and LATSCHEN- 

 BERGER, VOIT and FRIEDLANDER, and others. 2 In the experiments 

 of the two last-mentioned investigators neither casein (as milk) nor 

 hydrochloric-acid myosin or acid albuminate (in acid solution) was 

 absorbed, while, on the contrary, about 21 per cent of ovalbumin or 

 seralbumin and 69 per cent of alkali albuminate (dissolved in alkali) 

 were absorbed. MENDEL and ROCKWOOD, on the contrary, in experi- 

 ments with casein and edestin in the living intestinal loop, could prove 

 only the slightest absorption on excluding digestion as completely as 

 possible, while the corresponding proteoses were abundantly absorbed. 



It is difficult to decide in these experiments as to how far the pro- 

 teins were taken up in an actually unchanged or partly modified form. 

 The alimentary albuminaria, observed repeatedly after the introduction 

 of large quantities of protein into the intestinal canal, indicates an 

 absorption of undigested protein under certain circumstances. To decide 

 this question the biological method, using the precipitine reaction, has 

 been made use of, and ASCOLI and ViGNO, 3 using this method, claim to 



1 Zuntz and v. Mering, Pfliiger's Arch., 32; Neumeister, Verb. d. phys.-med. 

 Gesellsch. zu Wiirzburg, 1889, and Zeitschr., f. Biologie, 27; Friedenthal and Lewan- 

 dowsky, Arch. f. (Anat. u.) Physiol., 1899; Munk and Lewandowsky, ibid., 1899, 

 Supp.; Oppenheimer, Hofmeister's Beitrage, 4; Mendel and Rockwood, Amer. Journ. 

 of Physiol., 12; Heilner, Zeitschr. f. Biol., 50, and Munch, med. Wochenschr., 49; 

 Cramer, Journ. of Physiol., 37, with Pringle, ibid.; Rona and Michaelis, Pfliiger's 

 Arch., 123 and 124; v. Korosy, Zeitschr. f. physiol. Chem. 62, 68 (1909), 69, 313 (1910). 



2 Briicke, Wien. Sitzungsber., 59; Bauer and Voit, Zeitschr. f. Biologie, 5; Eich- 

 horst, Pfliiger's Arch., 4; Czerny and Latschenberger, Virchow's Arch., 59; Voit and 

 Friedlander, Zeitschr. f. Biologie, 33. Contradictory observations can be found in 

 Keller, Beitr. z. Frage d. Resorption im Dickdarm. Inaug.-Dissert. Breslau, 1909. 



3 Zeitschr. f . Physiol. Chem., 39. 



