502 DIGESTION. 



Since the first investigations of ZUNTZ and v. MERINO on this sub- 

 ject several experimenters, such as NEUMEISTER, FRIEDENTHAL and 

 LEWANDOWSKY, MUNK and LEWANDOWSKY, OPPENHEIMER, MENDEL, 

 and ROCKWOOD, HEILNER, CRAMER and PRINGLE, MICHAELIS and RONA 

 and others, 1 have shown, without any doubt, that the animal body can 

 more or less completely utilize different, parenterally introduced pro- 

 teins, although different varieties of animals show a difference in this 

 regard. Still we do not know where and how these foreign proteins are 

 changed and assimilated, but CRAMER ascribes great importance to the 

 leucocytes in this regard. 



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 LATSCHENBERGER, 

 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. MEN- 

 DEL and ROCKWOOD, on the contrary, in experiments with casein and 

 edestin in the living intestinal loop, could prove only the slightest absorp- 

 tion on excluding digestion as completely as possible, while the corre- 

 sponding proteoses were abundantly absorbed. 



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

 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 have shown the 

 passage of non-modified protein into the blood and lymph. Based upon 

 many investigations on this subject we can consider it possible that under 

 certain circumstances, as on flooding the intestinal canal with protein, 



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

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

 dowsky, Arch. f. (Anat. u.) Physiol., 1899; Munkand 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, Pfluger's Arch., 123 

 and 124. 



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

 horst, Pfluger'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. 



8 Zeitschr. f. physiol. Chem., 39. 



