NUTRITION. 391 



fined to a few weeks or months we probably should have failed to realize 

 the exceptionally large mortality which subsequently involved our 

 rye-fed animals. The seemingly good nutrition of the rye-fed animals 

 in the earher periods of their life makes it unlikely that the proteins 

 per se are chargeable with the untoward results subsequently exhibited 

 by this group of animals as a whole. What other deleterious factor, 

 if any, may be present we are as yet unable to state. 



In confirmation of earlier experience, we have again demonstrated 

 that growth to large adult size can be completed at a normal rate on a 

 food containing a liberal content of the entire wheat kernel. Several 

 litters of young were secured from females on such a diet. 



In order to ascertain the comparative value of the total proteins of 

 the individual cereals, we have made a numerical comparison of the 

 gains per gram of protein eaten and calorific intakes during comparable 

 periods. The upshot of this has been to show a comparative equality 

 of the four types of cereal proteins recorded, particularly when the gains 

 which they promote per gram of protein consumed are contrasted with 

 those secured within comparable periods of growth by the use of pro- 

 teins from other sources. To quote our published report, "we were 

 surprised to find that the efficiency of the entire wheat kernel, as well 

 as that of the other cereal grains studied, without supplementary pro- 

 teins, was so far superior to that ascertained by us earher in the study 

 of the endosperm. The utiHzation data secured by us testify to the 

 unexpected availability for growth of the proteins of these whole 

 cereals." 



Early in our studies on the comparative nutritive value of different 

 proteins, the failure of gliadin to permit satisfactory growth was re- 

 peatedly demonstrated. On diets in which gliadin is the sole protein, 

 animals grow very slowly for a long time. This result was demonstrated 

 to be due to the comparative deficiency of gliadin in lysine, an in- 

 dispensable amino acid which apparently can not be synthesized by 

 the animal organism. In order to furnish the essential water-soluble 

 vitamine in these gliadin-feeding experiments, we formerly employed 

 our protein-free milk and later dried yeast, both of which products 

 contribute a small amount of protein to the diet. Since this protein 

 may supplement the gliadin to some extent and thus provide a protein 

 mixture more adequate for growth than is gliadin alone, we have re- 

 peated the gliadin-feeding trials, supplying the necessary water-soluble 

 vitamine in the form of a protein-free preparation made from yeast 

 in the way refeiTed to in our report for 1919. The results are different 

 from our earlier ones in that the young animals have not grown at all 

 during a long time. The veiy small content of lysine in the gliadin 

 evidently suffices for the wear-and-tear needs of the body, but in the 

 quantities eaten did not permit any increment of tissue. This is a 

 good illustration of the usefulness of the concentrated protein-free 



