112 THE VITAMINS 



Benedict, 1918), and little if any of the antineuritic vitamin (McCol- 

 lum and Kennedy, 1916; Chick and Hume, 1916-17; Vedder and Clark, 

 1912; Chamberlain, Vedder and WilHams, 1912). While Mitchell 

 pointed out that if this relation should be abundantly confirmed by 

 future research "it may of itself effectively dispose of any contention 

 of the identity of the two vitamins," he showed that the evidence as 

 it stood at the time (1919) did not amount to finality on account of 

 the variability of the vitamin content of vegetables, roots and tubers 

 in different stages of freshness and maturity of the material, the lack 

 of sufficient experiments on the antineuritic and growth-promoting 

 properties of the same vegetable samples and the unreliability of experi- 

 mental results in investigations of the comparative antineuritic prop- 

 erties of foods when polished rice, in itself defective in several factors 

 other than the antineuritic vitamin, is used as the basal diet. 



Experiments with unpolished rice were considered to afford some 

 evidence of the lack of identity of water-soluble B and the antineuritic 

 vitamin, as shown by the observation of McCollum and Davis (1915b) 

 that unpolished rice is adequately supplemented by casein, salt and 

 butterfat, thus implying a sufficiency of water-soluble B; and of Gib- 

 son and Concepcion (1914) that unpolished rice does not furnish com- 

 plete protection against polyneuritis in pigeons, which, if confirmed, 

 would show an insufficiency of the antineuritic vitamin. The experi- 

 ence of other investigators, however, does not bear out that of Gibson 

 and Concepcion. 



The second point, that lack of vitamin B in the diet of various 

 species of experimental animals results in symptoms of nerve degen- 

 eration and paralysis, was dismissed with references to the observation 

 of Osborne, Wakeman and Ferry (1919) that such symptoms do not 

 always develop on a diet lacking in water-soluble B, and of Hart, 

 Miller and McCollum (1916) that "malnutrition histologically charac- 

 terized by nerve degeneration may result from the presence of toxic 

 materials in apparently normal food products and in the presence of 

 all known factors essential for continued growth and well-being." (It 

 is now known that nerve symptoms usually develop in rats only in 

 the presence of small but insufficient allowances of vitamin B. With 

 complete deficiency, experimental animals may die before the neuritis 

 develops.) 



As an illustration of the third point, that similarity in extraction 

 points to the identity of the two vitamins, the statement of McCollum 

 and Simmonds (1918) was quoted; their argument of the improbability 

 of two or more physiologically indispensable substances possessing the 



