THE FOLIC ACID COMPLEX 



microbiologically active vitamin Be. K. K. Krueger and W. H. 

 Peterson,^® on the other hand, reported that vitamin Be concentrates 

 prepared from yeast were just as active towards L. helveticus and S. 

 faecalis R as were similar preparations from liver. 



O. D. Bird and M. Robbins ^^ also found that both micro-organisms 

 responded to vitamin Be conjugate, although L. helveticus responded 

 in an abnormal manner, not only to crude preparations of vitamin Be 

 and the conjugate, but also to the crystalline conjugate. The diver- 

 gence from the standard curve was in fact particularly noticeable with 

 the latter. After incubation with vitamin Be conjugase (see page 

 479), all the preparations gave a response corresponding closely to 

 that of the standard. With S. faecalis R the response fell almost on 

 the standard curve even without incubation with vitamin Be con- 

 jugase. 



It was not unreasonable, therefore, on the basis of this evidence 

 to suppose that folic acid, the three L. casei factors, the SLR factor 

 and vitamin Be and its conjugate were very closely related. Unfor- 

 tunately, however, several other growth factors under investigation 

 at about the same time also appeared to be closely related to the 

 seven factors so far discussed, and it became difficult to determine the 

 relationships of all these factors to one another. 



Other Chick Factors 



Olher factors that appeared to be related in some way to the folic 

 acid complex were the factor U of E. L. R. Stokstad and P. D. V. 

 Manning,2i factors R and S of A. E. Schumacher, G. F. Heuser and 

 L. C. Norris,^^ and vitamins B^, and B^ of Briggs et alP (see also 

 page 614). 



The guinea-pig factor, factor GPF i, of D. W. Woolley and H. 

 Sprince ^^ also appeared to be closely related to the group. 



Vitamin M and Xanthopterine 



In 1932, L. Wills and H. S. Bilimoria ^^ showed that monkeys 

 developed anaemia, leucopenia and granulocytopenia when main- 

 tained on a diet similar to that associated with human tropical macro- 

 cytic anaemia in India. The anaemic monkeys were cured by 

 administration of a yeast extract. Similar results were obtained by 

 Langston et al.,^^ who also showed that the leucopenia and granulo- 

 cytopenia were relieved by concentrates prepared from either liver or 

 yeast ; they termed the responsible factor, vitamin M. 



A year previously, R. Tschesche and R. J. Wolf ^^ had reported 

 that an anaemia induced in rats by the feeding of goats' milk could 

 be cured by administration of xanthopterine, the yellow pigment 



460 



