62 THE VITAMINS 



phoric acid. It contains no amino nitrogen, but does contain sulfur, 

 which is given off on treatment with alkaH in the form of hydrogen 

 sulfide. The sulfur content increases with purification, but it is prema- 

 ture to pass an opinion as to whether the sulfur is a part of the active 

 .substance." (Cf. Guha and Drummond, 1929.) 



Another method for the extraction of vitamin B was suggested by 

 McCoUum and Kruse (1926). On the assumption that vitamin B 

 might be a tertiary base capable of combining with acids, and that the 

 resulting salts may be more soluble in 95 per cent alcohol than the 

 vitamin itself, extracts were prepared from wheat germ with hot 95 

 per cent alcohol containing 1 per cent of various organic and inorganic 

 acids. After evaporation of the solvent, these extracts were tested for 

 their content of vitamin B by feeding experiments with young rats 

 according to the technique of McCollum and Simmonds (1918). 



An extract thus prepared from wheat embryo with 95 per cent of 

 alcohol alone showed at the most only slight traces of vitamin B. This 

 was also true of extracts containing acetic, citric, sulfuric, hydrochloric, 

 or phosphoric acid, but those containing nitric, benzoic, or lactic acid 

 showed the presence of appreciable amounts of the vitamin and excel- 

 lent results were obtained with extracts containing 1 per cent of either 

 gallic or tannic acid. The active extracts were thought to offer promise 

 in further attempts at isolating the vitamin. 



The possibiHty of forming soluble double salts of the vitamin with 

 a metallic salt was also tested. An extract prepared from wheat embryo 

 with 95 per cent alcohol containing 1 per cent of either zinc chloride 

 or cadmium chloride was said to show some activity, but several other 

 salts tested gave negative results. (Cf. Jansen and Donath, 1929.) 



As will be developed more fully in Chapter III, much experimental 

 evidence has been adduced since 1919 indicating that a number of indi- 

 vidual substances contribute to the effects formerly ascribed to "water- 

 soluble B." Peters in a memorandum to Nature (September 14, 1929) 

 indicates that there are at least five factors concerned, and it is by no 

 means certain that the list is complete. 



Peters recognizes (1) the heat-labile antineuritic vitamin, necessary 

 for both pigeons and rats; (2) a second heat-labile factor needed for 

 pigeons (Williams and Waterman) ; (3) another heat-labile factor 

 necessary to rats (Reader) ; (4) a relatively heat-stable factor needed 

 by the rat (Smith and Hendrick) ; and (5) a heat-stable water- 

 insoluble (?) yeast factor necessary for rats (Hunt). 



It is not possible to evaluate all of the earlier data regarding vitamin 

 B (Bi), the growth promoting and polyneuritis-preventive vitamin for 



