CHAPTER III 



HEREDITY AND THE INFLUENCE OF ENVIRONMENTAL 



FACTORS ON THE OPTICAL ACTIVITY OF 



BIOLOGICAL MATERIAL 



Pasteur (1860) wondered how living beings would dif- 

 fer from what they are if the basic chemical substances 

 which compose them would change the sign of their opti- 

 cal rotation. Emil Fischer (1890) attempted to show how 

 this question can be answered experimentally. ''If it 

 proves possible", he writes, '"to feed plants, moulds or 

 yeasts with unnatural optical isomers of different sub- 

 stances, should one not expect that such a change in the 

 constructive material would result in a modification of 

 the delicate molecular architecture and of the entire 

 structure of organisms ? The biologists have not yet 

 studied this question because the chemists have not given 

 them the substances necessary for such experiments". At 

 present, fifty j^ears after Emil Fischer made this state- 

 ment, we know that such transformations of biological 

 structures are impossible, as the following data will show. 



1. The Impossibility of Iiirertinf/ the Optical Proper- 

 ties of the Primary Constituents of Protoplasm. It is now 

 well established that, if one gives to microorganisms 

 unnatural food material as, for instance, laevorotatory 

 leucine, they are simply unable to make use of such food 

 as they do not possess the suitable enzymatic outfit. This 

 was soon ascertained by Fischer himself who found that 

 laevorotatory glucose is practically not fermented by 

 yeast cells (Fischer and Thierf elder, 1894). 



In the light of modern knowledge one would not expect 

 that a simple change in nutrient conditions would deter- 



59 



