FERTILE BREEDING STOCKS 18-6 



from mating of weak or slow fermenters by strong fermenters. 

 The simplest explanation according to classical Mendelian theory 

 is that two different alleles were involved, both controlling the fer- 

 mentation and the nonfermenter was the segregant carrying both 

 negative alleles. This explanation will be tested (Chapter 26) and 

 shown to be inadequate. It is proposed that only a single pair of 

 alleles is involved and that the phenomenon results from the 

 transfer of fermentative ability from the weaker to the stronger al- 

 lele in the heterozygote. 



