1917] FOODS — HUMAN NUTRITION. 265 



although the amount of the increase was not proportional to the amount of 

 meat eaten. Although cooking increased the amount of creatinin present in 

 meat, cooked meat did not necessarily cause a greater increase in urinary 

 creatinin than uncooked meat. Creatinin administered by the mouth was 

 eliminated as such only to a slight extent and did not greatly change the 

 excretion of creatinin. 



Feeding experiments with a dietary in which tyrosin is reduced to a 

 minimum, G. Totani (Biochem. Jour., 10 {1916), No. S, pp. 382-398 ) .—Experi- 

 ments were conducted with laboratory animals (rats) to obtain information 

 regarding the necessity for tyrosin in the diet. In one experiment caseinogen, 

 freed as completely as possible from tyrosin, was used as the basis of the diet, 

 and in another both hydrolyzed and nonhydrolyzed gelatin were used. The re- 

 sults of the work are summarized as follows : 



" Tyrosin could not be isolated quantitatively from the hydrolysis products 

 of caseinogen. When the removal of tyrosin from the amino-acid mixture is 

 made as complete as possible and is effected to an extent which certainly 

 leaves only minimal quantities of this constituent, there appears to be no 

 effect upon the nutritive value of the amino-acid mixture. 



" In the case of the rat, the nutritive efficiency of gelatin is greatly increased 

 by previous hydrolysis. Gelatin when fed intact appears to be badly digested 

 and absorbed. The possibility of completely replacing the protein of a diet by 

 hydrolyzed gelatin, plus certain amino acids, is confirmed. 



" Some evidence is offered that the addition of tryptophane alone to the 

 hydrolysis products obtained from pure gelatin made these efficient in main- 

 taining the nutrition of animals." 



Feeding experiments with kynurenic acid, C. Asayama {Biochem. Jour., 

 10 {1916), No. 3, pp. 466-^72, figs. 4). — Laboratory animals (rats) were given a 

 basal diet, which supplied all of the amino acids of protein except tryptophane. 

 To this diet tryptophane was added in one series of experiments, and kynurenic 

 acid, a metabolic product of tryptophane, in another series. Determinations 

 of the body weight and the general nutritive condition of the animals showed 

 that the nutritive value of the diet was enhanced by the addition of trypto- 

 phane, but when tryptophane was absent from the food no improvement of 

 nutrition was observed on the addition of kynurenic acid. 



The role of leucocytes in the work on intermediary metabolism of carbo- 

 hydrates, P. A. Levene and G. H. Meyer (Ann. Inst. Pasteur, 30 {1916), No. 4> 

 pp. 155-159). — In the experiments here i-eported leucocytes, practically free from 

 bacteria, were found to convert six carbon chain-sugars into methylglyoxal, and 

 this in turn into lactic acid. By substituting glucose derivatives for glucose 

 it was found that glycolytic enzyms of animal tissues had no effect on those 

 hexoses in which one or more hydrogen atoms had been replaced by other 

 radicals. 



The mechanism of cholesterol absorption, J. H. Mueller {Jour. Biol. Chem., 

 27 {1916), No. 2, pp. 463-480). — The experiments here reported were carried out 

 Avith laboratory animals (dogs). In studying the mechanism of cholesterol 

 absorption analyses were made of the gastric and intestinal contents. After 

 feeding cholesterol the absorption of cholesterol was followed through a 

 thoracic duct fistula with experimental elimination of certain of the gastric 

 juices. Experiments were carried out in vitro dealing with the possible action 

 of various enzyms upon cholesterol. 



The data obtained showed that bile was more closely connected with 

 cholesterol absorption than with that of neutral fats. Experiments in vitro 

 showed that " free cholesterol, in the presence of fatty acids and a suspension 



