54 THE VITAMINS 



sugar, starch, lard, agar, and salts in feeding experiments conducted 

 on young rats. The necessity for providing the fat-soluble vitamin, 

 as pointed out by Osborne and Mendel and by McCoUum, had appar- 

 ently not been recognized by these w^orkers. Osborne and Mendel 

 (1917a) called attention to the absence of butterfat in the diet used 

 by Funk and Macallum and reiterated their belief that "unless all the 

 other necessary factors of the diet are adequately supplied the presence 

 or absence of the water-soluble vitamin can not be demonstrated." In 

 the light of later developments this paper contains several significant 

 statements. For the first time emphasis w^as given to what is now con- 

 sidered to be one of the most important properties of vitamin B, its 

 stimulation of the appetite. In attempting to explain this, the opinion 

 was expressed that the water-soluble vitamin exerts a favorable influ- 

 ence upon metabolism, improving the general condition of the animal 

 and thus increasing its appetite, rather than merely rendering the food 

 mixture more palatable and thus inducing the animal to eat more. Sub- 

 sequently it was demonstrated experimentally that an animal's appetite 

 for vitamin B-free food can be improved by feeding the vitamin sepa- 

 rately in the form of a small amount of dried yeast or dried spinach. 

 Another significant observation made at this time was that the rapidity 

 of growth was related to the quantity of yeast fed. To promote normal 

 growth in white rats with dried yeast as the sole source of water- 

 soluble vitamin in their experiments required the presence of about 

 2 per cent of yeast solids in the food mixture. The question as to 

 whether or not the v^^ter-soluble vitamin with which they were dealing 

 was identical with the antineuritic vitamin was considered unanswered, 

 although attention was called to the opinion of Funk and Macallum 

 that "the growth-promoting substance is analogous to and possibly 

 identical with the beriberi vitamin, but that considerably larger quan- 

 tities of vitamins are necessary for stimulating growth than for curing 

 beriberi." The necessity for carrying feeding experiments through more 

 than one generation, the recognition of which led later to the discovery of 

 vitamin E, was brought out in the concluding statement in this paper 

 in which attention was called to the observation that yeast as a source 

 of water-soluble vitamin had not given as good results as were obtained 

 from the use of protein-free milk. "Although some of the animals 

 brought up on the yeast-containing foods have given birth to young, thus 

 far none of the latter have been reared." The work of Osborne and 

 Mendel made it plain that this water-soluble vitamin so often referred 

 to as "growth-promoting" is certainly essential to normal nutrition at 

 all ages. 



