218 P. P. Slonimski and H. de Robichon-Szulmajster 



We can turn now to the cof actors. Their addition con- 

 siderably changes the action of euflavine. Addition of E acts 

 hke that of adenine, i.e. suppresses the occurrence of mutation 

 (Table IV). On the contrary, the addition of T, which derives 



Table IV 

 Antimutagenic action of cofactor E 



Conditions: Adenine 0-15 mg./ml. 



Source of cofactor: commercial erythrose batch c-l : 1 mg./ml.; 



batch c~2 : 1 mg./ml. 

 synthetic derivative of pure d -erythrose 

 (preparations j-2 and j-4 : equiv. 1 mg./ml.) 



from the threo isomer of tetrose instead of the erythro one, 

 potentiates the action of euflavine. In other words, it acts 

 against adenine (Table V). Cofactor T by itself does not pro- 

 duce mutation. 



