SHOETEE AETICLES AND DISCUSSION 



THE EFFECT OF YEAST ON THE UTILIZATION OP 

 FOOD BY WHITE MICE.^ 



In the present paper the question of the effect of the so-called 

 vitamines on basal metabolism is considered and a procedure is 

 indicated whereby it is believed more conclusive data may be 

 obtained on the question. Preliminary experiments are described 

 illustrating the method. 



Several years ag-o Hopkins- in a carefully carried out experi- 

 ment investigated the effect of a small addendum of milk to a 

 diet of purified food stuffs. In brief his method was to feed in 

 pairs two sets of young rats of the same origin, weight, etc., on 

 a basal vitamine-free food and to one set give a small addendum 

 of milk and determine the food intake and growth 

 By comparing the energy consumption and growth i 

 of the two sets of animals and by comparing these factors on the 

 same set of animals after reversing the diets he was able to 

 show "that the small milk addendum reduced the food con- 

 sumption for a given weight increment to one half or less." 

 In other words the vitamine increased greatly the animal's 

 power to utilize its food in the production of growth. And as 

 he showed that this was not due to difference in absorption 

 from the intestines, the vitamine must have an effect on some 

 factor involved in basal metabolism. 



A number of the criticisms that could be made of Hopkins' 

 method have been discussed frankly by him and there is left 

 little or no doubt concerning his conclusions. They have. hoAV- 

 ever, such an important bearing on problems in nutrition tliat 

 it seems very desirable that the question be investigated from all 

 angles^ and particularly with other animals,* and with vitamines 



1 Contribution from the Department of Pharmacology, Harvard Medical 



2 J. Physiol, 1912, 44, 425; see also Biochem, J., 1913, 7. 97. 



3 Recently Eddy (J. Biol Chem., 1920, XXXIV; see also Am. J. nis. 

 Children, 1917, 14, 189), has reported cases of marasmic infants which 

 showed an increase in the utilization of food, when given vitamine extracts 

 prepared from beans. 



* In another connection the writer has found that mice and rats react dif- 

 ferently with certain diets. The question is still open whether or not this 

 difference is qualitative or quantitative. 



