346 Vitamines and Deficiency Diseases [June-September 



any other proteins so far as growth is concerned. Street (142) has 

 compared the value of sanatogen and casein for growing rats but 

 could not detect a difference between these two f ood-stuffs. Hektoen 

 (143) found that the production of anti-bodies was normal in rats 

 fed with pure vegetable proteins (Osborne and Mendel's diet). 



The experiments on the influenae of isolated proteins, with addi- 

 tions of certain amino-acids, show what had previously been demon- 

 strated : that amino-acids, like trypophan, tyrosin, lysin and cystin, 

 are indispensable components of a complete diet. In experiments on 

 growth it is obviously essential that the protein in the diet should 

 yield all the necessary amino-acids in adequate amounts. 



Importance of vitamines for growth. Until recently the 

 growth Problem had been studied only on rats, mice, dogs and pigs. 

 I have extended these studies to chickens and, to my surprise, found 

 that practically all the preparations which stimulated growth in rats 

 failed to do so in young chickens. It was also found that polished 

 rice as well as unpolished rice was entirely inadequate to stimulate 

 growth in these animals. The best results ( 144) were obtained by 

 adding yeast to an unpolished-rice diet. On these diets, however, 

 all the chickens died in several weeks. On adding cod-liver oil to 

 an unpolished-rice diet the animals remained in fairly good health 

 for several months but no growth resulted (130). The addition of 

 tumor-tissue (Rous's sarcoma) also had a stimulating effect. 



In another series of experiments I tried the effect, on the growth 

 of chickens, of an addition of phosphotungstic precipitate, and of 

 phosphotungstic filtrate, to an unpolished-rice diet. No growth was 

 obtained (145). It seems, therefore, that growth in chickens is de- 

 pendent on such substances as are contained in living worms, for 

 even additions of fresh grass and salad to the inadequate diets 

 were without effect. 



Experiments were also carried out on young chickens with both 

 germinated and ungerminated oats, rice and barley, but these diets 

 proved to be unsuitable for young chickens. The experiments will 

 be repeated on chickens and rats. 



In conjunction with Macallum (130) experiments were per- 

 formed on rats in the diets for which various portions of the starch 

 were replaced with unpolished rice or with polished rice. The per- 



