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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, Bubcutaneously, or into a body-cavity, i.e.,
evading the intestinal canal, or, as it is called parenteral.
Since the first investigations of Zuntz and v. Mering on this sub-
ject, several experimenters x
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 Yoit, Eichhorst, Czerny and Latschen-
berger, Yoit and Friedlaxder, 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 en 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; Xeumeister, Verh. d. phys.-med.
Gesellsch. zu Wiirzburg, 18S9, and Zeitschr., f. Biologie, 27; Friedenthal and Lewan-
dowsky, Arch. f. (Anat. u.) Physiol., 1S99; Munk and Lewandowsky, ibid., 1S99,
Supp.; Oppenheimer, Hofmeisters Beitrage, 4; Mendel and Rockwood, Amer. Journ.
of Physiol., 12; Heilner, Zeitschr. f. Biol., 50, and Munch, med. Wochenschr., 49;
Cramer, Journ. of Physiol., 3", with Pringle, ibid.; Rona and Michaelis. Pfluuer’s
Arch., 123 and 124; v. Korosy, Zeitschr. f. physiol. Chem. 62, 68 (1909), 69, 313 (1910).
2
Brucke, Wien. Sitzungsber., 59; Bauer and Voit, Zeitschr. f. Biologie, 5; Eich-
horst, Pfliiger’s Arch., 4; Czerny and Latschenberger, Yirchow’s Arch., 59; Voit and
Friedlander, Zeitschr. f. Biologie, 33. Contradictory observations can be found in
Keller, Beitr. z. Frage d. Resorption im Dickdarm. I naug.-Dissert. Breslau, 1909.
3
Zeitschr. f. Physiol. Chem., 39.
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