236 IV. THE PRINCIPLES OF LIFE PHENOMENA 



in media containing piridoxin but no D-alanine are found to synthe- 

 size D-alanine. This finding has led to the discovery of a new enzyme 

 called "racemase" which produces DL-alanine from L-alanine (13). KOgl 

 and his collaborators (14) have repeatedly claimed that cancer cells 

 contain D-amino acids in considerably high amounts, while Christensen 

 et al. (15) have observed in vitro that a wide variety of amino acids, 

 natural and unnatural, of the d- as well as L-configuration was accu- 

 mulated in the free cells of mouse ascites carcinoma. The reason 

 why cancers are injurious may be partly accounted for by this fact. 



