Induced Mutational Changes in Yeast 119 



S. cerevisiae XII; the intensity of fermentation of the former 

 was somewhat less than that of the latter, during the first 4-5 

 days. 



The scheme of directed changes of the fermentative 

 properties of yeasts under the influence of a specific substrate 



J n:>c> 



5: 



HOCHO^^ 



XH,OH 



-Jilt (S 



H^H,OH 



Activation of 

 substrate by enzyme 



Fig. 1. Scheme of directed changes of fermentative properties of 

 yeast under the influence of the specific substrate. 



Acting 

 specific substrate 



Active enzyme appearing 

 in the cell 



(Fig. 1) shows that on the medium containing maltose, forms 

 of yeast have been obtained which readily ferment maltose 

 and less readily ferment sucrose. The enzyme developed in 

 these cells is a-glucosidase, which is known to activate maltose 

 and sucrose. 



Two forms of yeast have been obtained on the medium with 

 sucrose. One form is analogous to that obtained on maltose; 



