A CRITICAL INVESTIGATION AND AN APPLICATION 



OF THE RAT GROWTH METHOD FOR THE 



STUDY OF VITAMIN B. 



INTRODUCTION 



The term "vitamin B" is here used synonomously with 

 "water soluble B" as a designation for the water soluble 

 growth promoting substance whose existence as an essential 

 constituent of the food was demonstrated by Hopkins x & 2 , 

 Osborne and Mendel 3 ' 7 , and McCollum and Davis 8 ' 11 by 

 growth experiments with young mammals, chiefly rats. 

 Whether this is identical with the antineuritic substance stud- 

 ied by Eijkman 12 - 14 , Funk 15 - 16 , Williams 17 ' 20 and others 

 through experiments with birds, or with the "bios" of Wil- 

 diers 21 which shows a growth promoting property toward 

 yeast, does not concern the present investigation. The recent 

 publication of a monograph The Vitamins by the American 

 Chemical Society 22 makes it unnecessary to review previous 

 work at length in this connection. 



The importance of vitamin B as a factor in food values 

 makes desirable the standardization of the method of studying 

 this substance so as to permit of quantitative investigation of 

 the relative amounts in different foods or in the same food 

 before and after heating or other treatment to which foods 

 may be subjected in the course of preservation or cooking. 



When such methods are sufficiently developed they can 

 also be applied to the quantitative measurement of the concen- 

 tration of the vitamin at successive steps in attempts to iso- 

 late the substance from natural sources and bring it to a con- 

 dition of maximum purity for the determination of its chemi-. 

 cal nature. 



For the present investigation white rats were selected as 

 the experimental animal and dried skimmed milk as the vita- 

 min-containing food. Examination of the literature, as well 



