122 THE VITAMINS 



some cases in which growth was not promoted by either of two extracts 

 but was induced by a mixture of them. 



Further evidence that the term vitamin B had formerly included at 

 least two active factors, both of which are necessary for growth, was 

 furnished by Salmon (1927) in the report of an investigation which 

 had as its object (1) a comparison of the antineuritic and growth- 

 promoting values of the same samples of plant materials and (2) a 

 separation of extracts from these materials into fractions which might 

 possess either the antineuritic or the growth-promoting action alone. 

 The materials tested were seeds of soy beans and of velvet beans, and 

 leaves of velvet beans and of rape. The seeds proved to be more potent 

 than the leaves in their antineuritic value for pigeons and their pro- 

 tective value against polyneuritic symptoms and loss in weight in 

 rats. The leaves had a much greater growth-promoting action for rats 

 than the seeds. The observation that some of the rats on small allow- 

 ances of the seeds showed a tendency to lose their fur in patches and 

 occasionally to develop an inflammation around the eye was in har- 

 mony with the results reported by Goldberger and Lillie for similar 

 diets. 



The extracts used in the second part of the investigation consisted 

 of fuller's earth fractions (activated solid) of alcoholic extracts of the 

 seeds, and of acidulated extracts of the leaves prepared according to the 

 customary method of concentrating the antineuritic vitamin ; and the 

 residue left after the fuller's earth adsorption of the leaf extract. All 

 of the activated solids prevented polyneuritis in pigeons and rats. Rela- 

 tively larger amounts were required when prepared from the extracts 

 of the leaves than of the seeds. The residue had extremely weak anti- 

 neuritic and growth-promoting action when fed alone but when added 

 in small amounts with the antineuritic fractions showed marked growth- 

 promoting properties. 



Hassan and Drummond (1927) in the course of an investigation of 

 the possible relation between vitamin B and protein metabolism obtained 

 evidence of the multiple nature of vitamin B through the discovery 

 that an extract of yeast autoclaved at 120° C. for one hour at a strongly 

 alkaHne reaction and subsequently adjusted to the original hydrogen-ion 

 concentration of the extract by the addition of acid, was capable of 

 supplementing to a marked degree the growth-promoting effect of a 

 yeast concentrate prepared by the Seidell (1926) method, although 

 possessing no growth-promoting property when fed as the sole source 

 of vitamin B. 



At about the same time. Chick and Roscoe (1927) added to the 



