1920] FOODS — HUMAN NUTRITION. , 265 



bution, and interrelations of tlie nitrogen of tlie various constituents whicli ac- 

 company tlie chnnges in the level of the total nonprotein nitrogen. 



The l)lood samples were obtained from nurses and from patients suffering from 

 mental disorder but presenting no evidence of metabolic disorder. No quantita- 

 tive dietary regulation was attempted although the diet, being the usual hos- 

 pital diet, was qualitatively uniform. The methods employed for the determina- 

 tion of the various constituents were in general those recommended by Folln and 

 his associates (E. S. R., 29, p. 509; 41, p. 13). The results obtained are sum- 

 marized as follows : 



" While the total nitrogen, nonprotein nitrogenous constituents, and the 

 sugar of the blood vary in the same individual from week to week, there is a 

 tendency for the level of these vai^iations to be characteristically individual. 

 The sum of the average deviations of the constituents for any given individual 

 may be an index of the metabolic stability of that individual. 



" The order of relative variability of the constituents determined is cre- 

 atinin, total nonprotein nitrogen, total nitrogen, ciieatin, sugar, uric acid, 

 amino acid, urea, and rest nitrogen. A rough division can be made into groups 

 of low, intermediate, and high variability. 



" There is no practical difference between the absolute amounts of the con- 

 stituents found in bloods taken 14 hours after eating, i. e., before breakfast, 

 and 3.5 hours after this meal. The slightly lower values found before breali- 

 fast for the nonprotein, urea, and uric acid nitrogen are taken as meaning a 

 lessened metabolism. 



" The absolute amounts of the urea, creatin, uric acid, amino acid, and rest 

 nitrogen tend to decrease with decrease in level of the total nonprotein nitrogen. 

 The urea decreases to relatively the greatest extent. The absolute amount of 

 creatinin is a constant for the individual and for the species. It is independent 

 of quantitative changes in the level of the nonprotein nitrogen ; of the changes 

 in the concentrations of any of the other constituents determined ; and of the 

 individual variations in metabolic stability. There is no uniform quantitative 

 relation between the amounts of the creatinin and creatin nitrogen in the blood. 



" The distribution of the nonprotein nitrogen among urea and the other soluble 

 nitrogenous constituents of the blood is dependent to a great degree upon the 

 absolute amounts of the total nonprotein nitrogen present. The nitrogenous 

 constituents of blood that are commonly found in the urine, e. g., urea, creatinin, 

 and uric acid, seem to undergo the same type of absolute and relative change 

 with change in level of the total nonprotein nitrogen of the blood as they do with 

 the change from the high to low total nitrogen in the urine. The relative as 

 well as the absolute decline in the urea nitrogen of the blood accompanying the 

 decrease in the total nonprotein nitrogen is compensated for by a relatively 

 lesser absolute decrease in all the other nitrogenous con.stituents, which results 

 in an increase of the percentage of their nitrogen in terms of the nonprotein 

 nitrogen. The only apparent interrelation existing between any of the indi- 

 vidual constituents is that between the urea- and the rest nitrogen. There is 

 a tendency for a rise or fall in the blood urea to be accompanied by a change 

 in the opposite direction of the rest nitrogen." 



Alterations in the hemoglobin as well as the protein content of the 

 blood serum due to muscular work and sweating, E. Cohn (Ztschr. Biol., 

 70 (1919), No. 6-8, pp. S66-S70; abs. in Chem. Abs., H (1920), No. 8, p. 111,0).— 

 Determinations of the hemoglobin and protein content of the blood of human 

 sul)jects before and after muscular work and sweating showed no changes after 

 muscular exercise unaccompanied by sweating, but a decrease in the hemo- 

 globin and an increase in the protein of the blood in passive sweating. That 



