. / BSORPTIOJN OF 1' ROTE I PS. 439 
Changes m albumose and peptone during absorption} — Although 
there is no doubt that a considerable, if not the greater part of 
the proteid of the food is absorbed as albumose or peptone, these 
bodies are never found in appreciable amounj; in the blood. Schmidt- 
Mulheim 2 Btated that the maximum amount in serum is 0'028 per cent.: 
but recent experiments by Neumeister 3 have given an altogether 
1 legal ive result, and, according to this observer, albumoses are not present 
at all in blood, evi n in traces. 
Injected directly into the blood, albumoses and peptone arc treated 
by the organism as foreign bodies; they are not assimilable proteids, but 
are promptly excreted by the kidneys, unless injected in large quantities,' 1 
and in a short time practically all the peptone and albumose injected is 
found in the urine, while not a trace is to be found in the blood. 5 
That albumose and peptone are foreign substances in the blood stream, 
is shown not only by this rapid elimination, but by the fact that they 
possess, besides, marked toxic properties, and cause the death of the 
animal when injected in larger doses, producing an immense and rapid 
fall in arterial blood pressure ; in addition, they so alter the nature 
of the blood that on drawing it from the vessels it no longer coagulates, 
or does so very slowly. These results, taken in conjunction with the 
fact that normal urine never contains albumoses, even in traces, prove 
that the albumoses and peptones absorbed from the alimentary canal 
never reach the general circulation as such, but are somewhere on their 
route converted into other substances which can harmlessly enter the 
circulation. Positive experiments on the subject not only confirm this 
indirect proof, but clearly indicate that the change takes place in the 
lining epithelial cells. 
Seat of the modification of albumose and peptone, during absorption. — 
It might be supposed that the albumose and peptone disappeared as 
such in the liver ; this is not, however, the case. Schnridt-Alulheim 6 
found that the portal vein during proteid digestion contained no greater a 
percentage of these bodies than the arterial blood, and Neumeister 7 found 
that the portal vein, while absorption of peptone was going on, did not 
contain a trace of this material. Neumeister also circulated defibrinated 
blood, to which peptone had been added through a liver immediately 
1 In many of the papers referred to in this .section, "peptone" is used to signify what 
would to-day l>e called a mixture of albumose and peptone ; this lias usually been trans- 
lated by albumose and peptone, or by albumose. 
- Arch./. Aaat. u. Physiol.. Leipzig. 1?>0, S. 33. See also Hofmeister, Arch. f. 
Path. it. Pharrnakol., Leipzig, 18S5, Bd. xix. S. 17. 
3 Ztsehr. f. Biol., MiVnchen, 1888, Bd. xxiv. S. 277. Neumeister caught the blood 
from the carotid in ammonium oxalate to prevent clotting ; laked by shaking with ether ; 
removed ether ; saturated with ammonium sulphate; filtered; reduced filtrate by evapor- 
ating to a small bulk, filtering from time to time from crops of crystals ; and tested in final 
filtrate for albumoses by the biuret test with negative results. Control experiments showed 
that even a trace of albumose added to the blood intentionally could be easily identified. 
4 When large amounts are injected, the fall in arterial blood pressure is so great that 
secretion of urine is arrested. Even in such a case the albumose does not remain in the 
blood, but passes into the lymph (Shore, Journ. Physiol., Cambridge and London, 1890, 
vol. xi. p. 549). 
5 Ploz and Gyergyai, Arch. f. d. ges. Physiol., Bonn, 1875, Bd. x. S. 536 ; Hofmeister, 
Ztsehr. f. physiol. Chem., Strassburg, 18S1, Bd. v. S. 131 ; Schmidt- JIulheim, Arch. f. 
AnaA. u. Physiol., Leipzig, 1880, S. 33 ; Fano, ibid., 1881, S. 281 ; Shore, Journ. Physiol., 
Cambridge and London, 1890, vol. xi. p. 528. A similar effect follows subcutaneous 
injection (Hofmeister, loc. cit.). 
6 Arch. f. Anat. u. Physiol., Leipzig, 1880, S. 33. 
7 Sitzungsb. d. phys.-med. Gesellsch. zu JViirzburg, 18S9, S. 65 ; Ztsehr. f. I!i<>L. 
Munchen, 1888, Bd. vi. S. 287. 
