894 METABOLISM. 



In man and also in animals sometimes a rise in the nitrogen excretion 

 is observed about the second or third starvation day, which is then fol- 

 lowed by a regular diminution. This rise is explained by PRAUSNITZ, 

 TIGEESTEDT, LiANDERGREN, 1 as follows: At the commencement of star- 

 vation the protein metabolism is reduced by the glycogen still present 

 in the body. After the consumption of the glycogen, which takes place 

 in great part during the first days of starvation, the destruction of pro- 

 teins increases as the glycogen action decreases, and then decreases again 

 when the body has become poorer in available proteins. 



Other conditions, such as varying quantities of fat in the body, have 

 an influence on the rapidity with which the nitrogen is eliminated during 

 the first days of starvation. After the first few days of starvation the 

 elimination of nitrogen is more uniform. It may diminish gradually 

 and regularly until the death of the animals or there may be a rise in the 

 last days, a so-called premortal increase. Whether the one or the other 

 occurs depends upon the relation between the protein and fat content 

 of the body. 



Like the destruction of proteins during starvation, the decomposi- 

 tion of {at proceeds uninterruptedly, and the greatest part of the* calories 

 needed during starvation are supplied by the fats. According to RUBNER 

 and VOIT the protein catabolism varies only slightly in starving animals 

 at rest and at an average temperature, and forms a constant portion 

 of the total exchange of energy; of the total calories in dogs 10-16 per 

 cent comes from the protein decomposition and 84-90 per cent from the 

 fats. This is at least true for starving animals which had a sufficiently 

 great original fat content. If on account of starvation the animal has 

 become relatively poorer in fat and the fat content of the body has fallen 

 below a certain limit, then in order to supply the calories necessary, a 

 larger quantity of protein is destroyed and the premortal increase now 

 occurs (E. VOIT). The reason for this premortal rise in protein catabol- 

 ism is still not completely understood (SCHULZ and collaborators 2 ). 



Since the fat has a diminishing influence on the destruction of pro- 

 teins corresponding to what was said above, the elimination of nitrogen 

 in starvation is less in fat than in lean individuals. For instance, only 

 9 grams of urea were voided in twenty-four hours during the later stages 

 of starvation by a well-nourished and fat person suffering from disease 

 of the brain, while I. MUNK found that 20-29 grams urea were voided 

 daily by CETTI, B who had been poorly nourished. 



^rausnitz, Zeitschr. f. Biologie, 29; Tigerstedt and collaborators, 1. c.; Landergren, 

 Undersokningar ofver menniskans agghviteomsattning, Inaug.-Diss. Stockholm, 

 1902. 



2 Voit, Zeitschr. f. Biologie, 41; 167 and 502. See also Kaufmann, ibid., and N. 

 Schulz, ibid., and Pfliiger's Arch., 76, with Mangold, Stiibel and Hempel, ibid., 114. 



8 Berl. klin. Wochenschr., 1887. 



