1913'] Chemistry of Diet 183 



more ready formation of the fatty tissues of the body than 

 were they not supplied. However, we know recently that the 

 fat of the body surplus may be synthesized from the carbo-hy- 

 drate or protein of the diet and, further than that, we have 

 animal experiments where they have been fed into the second 

 generation and have given milk to their young on a fat-free 

 diet. When the fat is omitted from the dietary, the correspond- 

 ing calories must be supplied by the carbo-hydrate in order to 

 spare the protein. 



In the summary, the proteins are to a slight degree, 

 specific foods, but the carbo-hydrates and fats are not at 

 all so. Regarding protein specificially : Osborne and Mendel 

 say today, ''Whatever may be the source or chemical make-up 

 of the protein previous to its involvement in the nutritive pro- 

 cesses, the resulting tissue cells and fluids remain characteristic 

 and specific for the species." 



It is well known that by limiting the food supply of an un- 

 grown individual, its development may be retarded. If the 

 underfeeding is prolonged through the cycle of growth, 

 the full stature limited by heredity may not be 

 attained. The Sub-normal growth of immature animals 

 on such a typical experiment as wheat-gliadin — stunting 

 of albino rats suggests a chemical explanation of beneficial ef- 

 fects observed from a "change of environment, vacation, coun- 

 try air, mineral springs, and the like" when the individual in 

 his or her daily routine at home, may have been suffering from 

 a deficiency of some special chemical element or group, which 

 he required in greater amount. These specific substances which 

 we do not always get in sufficient quantity are typified in iodine 

 and its relation to the thyroid, grovs^th and control ; and a phos- 

 phorus deficiency, as shown in beri-beri. Certain individuals 

 have wasteful idiosyncracies, whereby they do not conserve all 

 the chemical elements and groups which reach the alimentary 

 tract in the food, and, consequently, they must be fed these 

 s'ame substances in greater quantity or in more assimilable 

 form. McCrudden, (Rockefeller Institute) has recently shown 

 that in certain cases of retarded growth there is faulty skeletal 



