764 EXPERIMENT STATION KECORD. 



It lias been claimed that the life of red blood corpuscles is very brief aud 

 tbat this necessitates an intensive repair. Experiments which are cited indicate 

 that this is not probable. At the present time there are no satisfactory methods 

 for maliing accurate observations regarding the renewal of the blood and organs. 



Concerning' the physiological nitrogen minimum, K. Thomas {Arch. Anat. 

 II. PhysloJ., Plnjswl. AM.. 1910, »s'h/j., pp. 2J,!)-2S.5 ; abs. in Chem. Zentm., 1912, 

 J, No. 2, p. 01). — The author studietl exi)erimentally the conditions under which 

 nitrogen metabolism can be reduced to the value represented by the " utiliza- 

 tion quota " and the conditions under which this quantity can be replaced by 

 nitrogen of food without increasing nitrogen metabolism, experiments being 

 made vs'ith himself as a subject and also with dogs. 



From the data obtained it appeared that the physiological nitrogen minimum 

 is influenced by 3 factors, namely, the biological value of the food nitrogen, 

 the formation of stored protein, and the amount of total energy metabolism of 

 the body. If food nitrogen and body nitrogen replace each other quantitatively, 

 if the formation of stored protein is hindered by the fractional feeding of pro- 

 tein, and if experimental conditions remain constant so that the energy require- 

 ments of the body do not change in a condition of niti'ogen hunger and with a 

 nitrogen supply which is sufficient for maintenance, then the physiological nitro- 

 g<eu niiDimum is equal to the " utilization quota." 



Theories of protein metabolism together with some of their practical 

 results, L. B. Mendel (Ergeh. Physiol., 11 {1911), pp. 418-525, dgms. 2).— This 

 important digest is preceded by a bibliography of the subject containing several 

 hundred references. 'Besides introductory material the article discusses the 

 theories of protein metabolism advanced by a number of investigators, the rela- 

 tion of digestion to protein metabolism, products of digestion, and problems of 

 protein structure. Another section deals with types of protein cleavage and 

 another with the value of protein in nutrition. Researches which have to do 

 with the protein minimum are summarized, together with other investigations 

 of the physiological value of different protein compounds and similar topics. 

 Protein standards in the diet are discussed particularly on the basis of R. H. 

 Chittenden's experiments (E. S. R., 20. p. 263). The final section deals with 

 the practical applications of Chittenden's theories and takes up at length the 

 work and criticisms of other investigators with reference especially to the low 

 proteid theory. 



A study of nitrogen metabolism in man, H. Labbe {Jour. Physiol, et Path. 

 G&n., 13 (1911), No. 2, pp. 191-211). — The author, accustomed to living on a 

 diet fairly low in protein, performed a 5-day test upon himself in order to 

 determine the character of the nitrogen metabolism when exceptionally low 

 quantities of protein were ingested. At the beginning of the experiments the 

 nitrogen in the diet, expressed in terms of protein, was equal to about 1 gm. per 

 kilogram of body weight, and was gradually reduced to 0.5 gm. Food materials 

 and the excreta were analyzed. 



The author concludes that with a normal subject in good health the nitrogen 

 equilibrium as it existed befoi-e the experiments was reestablished at the end 

 of the exi)eriments, this result being obtained without variation of weight 

 during a short experimental i>eriod and while the nitrogen ingested was gradually 

 reduced to about the minimum of nitrogen consumption. Notes are given on the 

 various products of nitrogen metabolism as they appear in the excreta. 



Concerning metabolism in nitrogen hunger, G. Kinbebg {Skand. Arch. 

 Physiol., 25 {1911), No. J,-5, pp. 291-31/,, flgs. 5; abs. in Chem. Zenthh, 1911, II, 

 No. l/f, p. lOJfl). — Nitrogen excretion under the experimental conditions sank 

 during the nitrogen hunger peilod with increasing rapidity and reached a 

 minimum of 5.17 gm. on the ninth day. 



