870 EXPERIMENT STATION RECOED. 



not fjiil to find them. As a matter of fact the nonprotein nitrogen of blood does 

 rise and sinJc lilie a tide with reference to absorption from the digestive tract 

 and the variations appear to be adeqnate to acconnt for all the nitrogen when 

 considered fi'om the right point of view. 



"An all-important function of the blood is to transport food from the digestive 

 tract to every tissue in the body ; this being so there is a priori no reason why 

 the transport of the amino acids from the blood to all the various organs 

 should be less prompt than the transport of those same amino acids from the 

 digestive tract into the blood." 



In connection witli their work the authors found " that while the liver almost 

 wholly abstracts the ammonia from the portal blood and probably converts it 

 into urea, it does not 'deamidize' the amino acids." This discovery led to the 

 hypothesis that the blood promptly transports the amino acids from the intes- 

 tine to every tissue in the body. 



Experiments were made with cats, in which solutions of urea, glycocoll, pan- 

 creatic digestion mixture, and egg albumin were injected. Each animal was 

 etherized, and a sample of blood taken from the right carotid artery and ffom 

 the portal vein. Ligatures were applied to prevent the escape of the materials 

 under absorption, and 45 minutes after injection the blood was again tested. 



The authors conclude as follows : 



" We have confined ourselves to the presentation of analytical results which 

 seem to show what becomes of tlie amino acids absorbed from the intestinal 

 tract. The muscles and other tissues as well evidently serve as a storehouse 

 for such reserve materials. The existence of such a reservoir must be taken 

 Into account in our theories of protein metabolism, for it certainly ought to 

 make at least some points clear which were not clear before. The peculiar lag 

 extending over several days in the establishment of a constant level of nitrogen 

 elimination when extreme changes are made in the nitrogen intake is probably 

 due to a filling or a depletion, as the case may be, of the reservoir. The differ- 

 ent results obtained when a single substance like creatin or an amino acid is fed 

 together with diets rich or poor in nitrogen would also be determined by the 

 condition of the reservoir. When full the creatin is eliminated and the amino 

 acid augments the urea output; when nearly empty both are retainetl. . . . 



" The analytical methods used are adaptations of colorimetric methods for the 

 determination of nitrogen, urea, and ammonia in urine. None of these have a? 

 yet been published in detail." 



Protein metabolism from the standpoint of blood and tissue analysis. — 

 II, The origin and significance of the ammonia in the portal blood. O. Folin 

 and W. Denis (Jour. Biol. Chcni., It {J912), No. 2, pp. 161-167).— The authors 

 refer to previous work and suggest the need of more refined analytical methods 

 in studying the question. The experiments which they carried on were made by 

 methods similar to those referred to above. 



T*hey conclude that the large intestine clearly is the chief or at least the most 

 constant source of the ammonia found in the portal blood, and that it is also 

 the chief seat of bacterial action. Since many of the bacteria, such as the 

 Bacillus coli, rapidly produce ammonia from albuminous materials, especially 

 in the absence of carbohydrates, the condition in the large intestine is ideal 

 for the production of ammonia. " Further, since the large intestine is prac- 

 tically never empty, there are always present the conditions for this ammonia 

 foi'mation, and that is why the ammonia in fasting animals is often as abundant 

 in the portal blood as during digestion." 



The total amount of ammonia which I'eaches the portal blood, it is pointed 

 out, is, as the experiments show, not very large, and in the authors' opinion it 

 is extremely unlikely that this ammonia is the cause of the disturbance pro- 



