390 CAENEGIE INSTITUTION OF WASHINGTON. 



to the sterling worth of our valued collaborator. Shortly before her 

 final illness Miss Ferry was engaged in the preparation of a somewhat 

 detailed description of the technic of the nutrition experiments which 

 has been followed for some time in our studies. This was done in 

 response to numerous inquiries from workers in other laboratories, who 

 like ourselves have recognized the great usefulness of the white rat as a 

 subject of nutrition investigations. The manuscript is now in press. 



The comparative study of barley, oats, rye, and wheat as sources 

 of protein, to which reference was made in the report of 1919, has been 

 continued. Our earlier experiments with these cereals were inconclu- 

 sive, because the rations included, during a part of the period, a small 

 amount of breweiy yeast containing protein, which possibly supple- 

 mented the cereal protein so as to increase the rate of growth. In our 

 latest experiments the entire cereal grains, finely ground, were fed along 

 with an adequate salt mixture and sufficient butter-fat to supply the 

 fat-soluble vitamine. On the basis of evidence obtained by both our- 

 selves and others, the quantities of the entire cereal grains used should 

 supply sufficient water-soluble vitamine. The experiments leave no 

 doubt of the adequacy of the barley proteins as a whole in the nutrition of 

 growth, for several of the rats grew to large adult size without any other 

 source of protein than that derived from this cereal. Some of the ani- 

 mals on the higher percentages of barley protein even suipassed the 

 normal rate of growth on ordinary mixed food. With the lower con- 

 centration of barley in the food the deficit of protein limited the rate 

 of growth, though even on the lowest percentage not inconsiderable 

 gains were made. 



The feeding experiments with pearled barley were not as satisfac- 

 tory. The growth obtained was relatively slight in comparison with 

 the more adequate gains on foods of a similar calorific nature, con- 

 taining 8 per cent of protein from the entire barley grain. The addi- 

 tion of vitamine in the form of yeast did not improve the results. It 

 is not unlikely that the milling process has removed fractions of the 

 barley protein residing in the outer layers of the grain, which supple- 

 ment the less effective proteins of the barley endosperm. In a similar 

 way it is known that the total proteins of wheat are superior to the 

 proteins of the endosperm of that cereal. 



In the case of the oat kernel the successful growth of several animals 

 to large size indicates that the total protein of the oat kernel furnishes 

 all the essential nitrogenous units if the intake of food and its concen- 

 tration of protein are adequate. For some reason the animals did not 

 eat the oat foods as readily as the barley rations, a fact which may ex- 

 plain the failure of a considerable number to thrive. 



Although several animals grew fairly well for a considerable period 

 on foods containing an adequate percentage of rye, they have invaria- 

 bly failed to reach a large size. Had our investigations been con- 



