Induced Mutational Changes in Yeast 123 



ability diminished. Twenty-seven of the cultures adapted to 

 fermentation of maltose were tested. All of these after having 

 been cultivated on wort-agar (for 268-509 days) and after 

 having been cultivated on the medium containing galactose 

 (for 54-56 days) completely retained their ability to ferment 

 maltose. 



(c) Inheritance of fermentative properties, developed by yeasts, 

 when crossed with their original forms : When cultures adapted 

 to fermentation of sucrose were crossed, by coupling of spores, 

 with the original S. glohosus 349, a hybrid was obtained which 

 readily fermented sucrose; this experiment was indicative of 

 the dominance of the sugar-fermenting property in the first 

 generation. In the second sexual generation we tested twenty 

 4-spore asci, all 80 spores of which germinated and produced 

 viable cultures. The tests for the ability to ferment sucrose 

 were continued over a period of one month. It was found that 

 nineteen asci showed very pronounced segregation as regards 

 the ability to ferment sucrose, i.e. in the ratio 2 : 2, and one 

 ascus in the ratio 3:1. 



When cultures adapted to fermentation of maltose were 

 crossed with the original S. glohosus 349, a hybrid was ob- 

 tained which readily fermented maltose. In the second sexual 

 generation we tested thirteen 4-spore asci, all of which showed 

 segregation as regards the ability to ferment maltose, in the 

 ratio 2 : 2. 



{d) Comparative analysis of fermentative properties of original, 

 altered and some other forms of yeasts having a close affinity 

 between them: As a result of experiments carried out by the 

 author on adaptation of S. globosus to fermentation of 

 sucrose and maltose, and of S. paradoxus to fermentation of 

 maltose and simple dextrins of malt-wort, new forms were 

 obtained which differed from the original strains as regards 

 their fermentative properties ; those obtained from S. globosus 

 are divided into 4 groups: 



Group 1. In contradistinction to S. globosus, these forms 

 ferment not only monosaccharides, but also sucrose and 



