VITAMIN B {Br) 53 



Thus an explanation was afforded for the observations previously noted 

 by Hopkins and Neville (1913) and others, that when purification of 

 the various ingredients of an artificial dietary is carried to a further 

 degree than usual the animals decline at a much more rapid rate than 

 when fed upon a similar diet which is less pure. 



Shortly after these papers Drummond (1916) published more de- 

 tailed evidence leading to the same conclusion, that lactose refined to a 

 degree ordinarily regarded as pure is likely to carry considerable amounts 

 of a growth-promoting substance soluble in water and alcohol and not 

 destroyed by exposure to 100° C. for six hours. This helped to explain 

 the discordant results obtained by various investigators in growth ex- 

 periments in which lactose had been a part of the experimental dietary 

 and to make more convincing the proof of the indispensability for nor- 

 mal nutrition of the water-soluble and fat-soluble vitamins. 



Similarity in occurrence and properties of the water-soluble growth- 

 promoting and the antineuritic vitamins had led to the suggestion, and 

 belief on the part of most workers, that these two were identical. 



jMcCollum and Kennedy (1916) held that the water-soluble B essen- 

 tial to growth is identical with the substance which prevents and cures 

 polyneuritis and that it may be extracted from fat-free wheat embryo 

 not only by water and alcohol but also by acetone, benzene and ethyl 

 acetate. They found evidence of the presence of this substance in the 

 juice of potato and cabbage as well as in extracts of wheat and oats. 



Funk and Macallum (1916a), in attempts to concentrate the water- 

 soluble growth-promoting vitamin in yeast by methods such as Funk 

 had used in his studies on the antineuritic vitamin, found that the 

 growth-promoting substance was almost entirely precipitated by phos- 

 photungstic acid, but that practically all of its activity was lost on 

 subsequent fractionation with silver salts. While their results did not 

 entirely parallel those of Funk, they concluded that the water-soluble, 

 growth-promoting substance is analogous to, if not the same as, the 

 antineuritic vitamin. At about the same time Eddy (1916) obtained 

 from sheep's pancreas an alcoholic extract containing a water-soluble, 

 growth-promoting vitamin capable of adsorption with Lloyd's reagent, 

 and of precipitation from the resulting extract by phosphotungstic 

 acid. In the treatment of the phosphotungstate both Funk and Macallum 

 and Eddy used the amyl alcohol method of Jacobs which does not seem 

 to have been used in the various methods of concentrating the anti- 

 neuritic vitamin. 



In both of the foregoing studies the activity of the various frac- 

 tions was tested by using them as supplements to a basal diet of casein, 



