A BIOLOGICAL ANALYSIS OF PELLAGRA-PRODUCING 
DIETS. 
IV. THE CAUSES OF FAILURE OF MIXTURES OF SEEDS TO 
PROMOTE GROWTH IN YOUNG ANIMALS. 
By E. V. McCOLLUM anp N. SIMMONDS. 
(From the Laboratory of Biochemistry of the School of Hygiene and Public 
Health of the Johns Hopkins University, Baltimore.) 
(Received for publication, December 26, 1917.) 
Our investigations on the composition of the diet in its relation 
to growth have made it clear that a food mixture may conform 
to the most approved standards with respect to its energy and 
protein content and in affording a considerable variety in flavors, 
and may be so prepared as to be highly attractive in appearance, 
and still be of such nature as to fail to nourish properly an ani- 
mal during growth. Such conditions are easily fulfilled if the 
diet is restricted to dishes prepared wholly from the seeds of 
plants or their milling products together with starch, sugars, 
. commercial syrups, vegetable fats, lard, flavoring extracts, and 
spices. 
Our extensive studies of seeds in which a single variety was 
fed with the addition of single or multiple purified food ingre- 
dients, have indicated that the seeds all show a close similarity in 
their dietary properties. Chemical analysis has revealed pro- 
nounced differences in the yields of the various amino-acids ob- 
tainable from isolated vegetable proteins. Tests by biological 
methods have established the fact that corresponding to these 
differences in the constitution of the proteins are equally great 
variations in nutritive values. In the preceding paper of this 
series (1) we have shown that the value of the protein mix- 
ture present in each of the more important seeds is without 
exception much lower than are those of milk. Judging from our 
studies on the physiological minimum of protein for maintenance 
in the rat, if milk proteins are assigned the value of 100, oat and 
millet seed proteins would be assigned a numerical value of 
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