ABSORPTION OF PEPTONES AND PROTEIDS. 397 



tration of their solution in the intestine. They pass into the blood- 

 vessels (Schmidt-Mill heim). When animals are fed on peptones (with 

 the necessary fat or sugar), they serve to maintain the body-weight 

 (Maly, Plosz, and Gyorgyai). Only minute quantities of peptone have 

 as yet been found in the blood (Drosdorff ) ; hence, it is assumed, either 

 that they are rapidly converted into true albuminous bodies, or that in 

 part at least, they undergo further decompositions, with which we are 

 as yet unacquainted. As, however, they can compensate for the total 

 metabolism of the proteids within the body, we must assume that they 

 are converted into proteids. 



Schmidt-Miilheim has recently found that, four hours after feeding a pig with 

 fibrin, a large quantity of crystalline propeptone (p. 331) can be obtained from 

 the blood. When 5 c.c. of a 20 per cent, solution of peptone in 0'6 per cent. 

 NaCl solution, for every kilo, of a dog, are injected into the blood, death is pro- 

 duced owing to paralysis of the blood-vessels (compare 28, II,/). Fano is of 

 opinion that the red blood-corpuscles take up the peptone, and subject it to further 

 changes. 



(4.) Unchanged true proteids filter with great difficulty, and much 

 albumin remains upon the filter. On account of their high endosmotic 

 equivalent they pass with extreme difficulty, and only in traces through 

 membranes. Nevertheless, it has been conclusively proved that un- 

 changed proteids can be absorbed (Briicke), e.g., casein, soluble myosin, 

 alkali-albuminate, albumin mixed with common salt, gelatin (Voit, 

 Bauer, Eichhorst). They are absorbed even from the large intestine 

 (Czerny and Latschenberger), although the human large intestine 

 cannot absorb more than 6 grms. daily. But the amount of unchanged 

 proteids absorbed is always very much less than the amount of 

 peptone. 



Egg-albumin without common salt, syntonin, serum-albumin, and fibrin are not 

 absorbed (Eichhorst). Landois observed in the case of a young man who took the 

 whites of 14-20 eggs along with NaCl, that albumin was given off by the urine for 

 4-10 hours thereafter. The amount of albumin given off rose until the third day 

 and ceased on the fifth day. The more albumin that was taken the sooner the 

 albuminuria appeared and the longer it lasted. The unchanged egg-albumin 

 reappeared in the urine. If egg-albumin be injected into the blood, part of it 

 reappears in the urine ( 41, 2) (Stokvis, Lehmann). 



(5.) The soluble fat-soaps represent only a fraction of the fats of 

 the food which are absorbed ; the greater part of the neutral fats being 

 absorbed in the form of very fine particles as an emulsion. The 

 absorbed soaps have been found in the chyle, and as the blood of the 

 portal vein contains more soaps during digestion than during hunger, 

 it has been assumed that the soaps pass into the intestinal blood- 

 capillaries. The investigations of Lenz, Bidder, and Schmidt render 

 it probable that the organism can absorb only a limited amount of fat 

 within a given period ; the amount perhaps bears a relation to the 



