66 OPT. ACTIV., HEREDITY AXD EXVTRONMENT 



fiuence of nitrogen nutrition and of temperature upon the 

 optical form of the lactic acid obtained in bacterial fer- 

 mentation. The effects of various incubation tempera- 

 tures are presented in Table 12. One sees that the tem- 

 perature does not influence the sign of the optical rotation, 

 but that the degree of racemization of the acid regularly 

 increases with the rise of temperature. 



Thus the old data of Kayser (1894) become clear. In 

 ditferent conditions of culture, the lactic acid formed by 

 a specific strain of bacteria possesses a different degree 

 of optical purity depending on the quantity of racemiase 

 contained in the bacterial cells. 



Recently Kopeloff (1937) has shown that racemiase is 

 sometimes lost in the transition of the R-f orms of lactic 

 acid bacteria into the S-forms. 



To summarize, the production of a specific optical 

 isomer, in the case of such secondary substances of the 

 protoplasm, or products of metabolism, as lactic acid, 

 represents a fixed hereditary character which is not de- 

 pendent on the conditions of cultivation. It is only such 

 processes as the velocity of a catalytic racemization of 

 secondary substances initially formed in the optically 

 pure state and the formation of racemiase which are de- 

 pendent on the culture conditions. The hereditary char- 



TABLE 12 



Influexce of the Temperature of Incubation upon the Optical Form 



OF the Lactic Acid Obtained in Fermentation 



(Katagiri and Kitahara, 1937) 



(The letters 1, d and dl indicate the optical rotation.) 



