FOODS — HUMAN NUTEITION. 263 



tein, a carbohydrate like starch, protein-free milk, and commercial lard, they 

 usually grow normally for about three months, but never attain their full size. 

 A partial or complete cessation of growth which results in a decline of body 

 weight occurs sooner or later, and ultimately ends in death if the diet is not 

 changed. The authors found that if part of the lard were replaced by other 

 natural fats recovery resulted. 



The results obtained in the present series of experiments are summarized as 

 follows : 



"The failure of lard to promote growth in the same manner as do other 

 natural fats (i. e., butter fat, egg yolk fat, cod liver oil) is not attributable 

 to deteriorating changes arising from heat or chemical agents in the commercial 

 manufacture of the jiroduct. Heating butter fat with steam does not destroy 

 its growth-promoting efficiency. 



" Beef fat also renders the inefficient diets used by us more suitable for pro- 

 ducing growth in rats than does lard. 



" When butter fat and beef fat are subjected to fractional crystallization 

 from alcohol, the growth-promoting factor remains in the mother liquid or 

 ' oil ' fractions. The fractions containing the fats with high melting points are 

 ineffective." 



Purin metabolism of man. — III, The decomposition of purin compounds 

 in the digestive canal, Y. O. Siven {Pfliiger's Arch. Physiol., 151 {1914), -A'o. 

 11-12, pp. 582-586). — It was found by artificial digestion experiments that the 

 purin compounds contained in bouillon were easily decomposed by cultures of 

 Bacillus coli. It is concluded that the loss (about 50 per cent) which the exog- 

 enous purins undergo during their passage through the human organism occurs 

 in the digestive canal, principally due to the action of the intestinal bacteria. 

 See also former work (E. S. R., 29, p. 63). 



The metabolism of vegetarians as compared with the metabolism of non- 

 vegetarians of like weight and height, F. G. Benedict and P. Roth (Jour. 

 Biol. Chein., 20 (1915), No. 3, pp. 231-241)- — Employing a unit respiration appa- 

 ratus, investigations were carried out to study the metabolism of vegetarians 

 and nonvegetarians, both male and female. In a discussion of the experi- 

 mental data the authors conclude " that living upon a vegetarian diet for a 

 longer or shorter period does not fundamentally alter the basic gaseous 

 metabolism. . . . 



"The average respiratory quotient found with the 22 vegetarians (i. e., 11 

 men and 11 women) was 0.S3, while the average quotient found with 132 indi- 

 viduals subsisting on a mixed diet (77 men and 55 women) was O.Sl. This 

 difference is slight and is wholly incompatible with the belief that vegetarians, 

 when in the post-absorxitive condition, have available any considerably larger 

 proportion of easily combustible carbohydrate material than have nonvege- 

 tarians." 



The metabolism of athletes as compared with normal individuals of 

 similar height and weight, F. G. Benedict and H. M. Smith (Jour. Biol. 

 Chem., 20 (1915), No. 3, pp. 243-252). — In these experiments the authors studied 

 the effect upon basal metabolism of abnormal amounts of protoplasm such as 

 are present in the body of the trained athlete. The subjects of the experiments 

 were divided into groups of approximately equal weight and height, each 

 group including athletes and nonathletes. The average heat production per 

 kilogram of body weight was for the athletes 26 calories and for the nonathletes 

 24.4 calories. The heat production per square meter of body surface was for 

 the athlete 863 calories and for the nonathlete 807 calories. 



