GROWTH AND FERMENTATIVE CAPACITY 14-13 



strains, the pair-wise comparison of the growths on the different 

 sugars exhibited exactly the same patterns as the corresponding 

 gas diagrams. For the purpose of this presentation a detailed dis- 

 cussion of the yield distribution would add little that is new to the 

 information already obtained from the analysis of the gas diagrams. 



Comparisons similar to those on glucose, levulose, and sucrose 

 given in fig. 14-10 to 14-12 were also carried out with both galac- 

 tose and maltose. The spot diagrams will not be given, but since 

 certain interesting biochemical types were noted, the results may 

 be briefly summarized. 



When behavior on glucose was compared with galactose, it was 

 found, as was to be expected, that the vast majority of strains fell 

 on the glucose side of the 45 degree line. Out of 150 strains ex- 

 amined only one showed marked preference for galactose. This 

 particular strain produced 5.7 units of gas on galactose and only 

 1.4 on glucose. The comparison of galactose against levulose 

 showed a decided preference for levulose in the vast majority of 

 strains. Four strains were found, however, that showed a signifi- 

 cantly better fermentative capacity when galactose was the sub- 

 strate as compared to that measured on the levulose medium. 



When gas production on maltose was compared with that on glu- 

 cose, it was found that the majority of strains could ferment glucose 

 with greater ease. Five of the 150 strains tested were unable either 

 to split maltose or to use it directly in some other fashion. As in 

 the case of the glucose -sucrose comparisons (fig. 14-10), several 

 biochemically anomalous strains were found. For example, one 

 strain produced only 1.2 units of gas on glucose and 5.3 units on 

 maltose. This would be difficult to understand if this strain meta- 

 bolized maltose by first splitting it into two glucose molecules. 



In the comparison of maltose versus levulose, the tendency was 

 toward better fermentation of levulose in 82 per cent of the strains 

 tested. This differs from the sucrose -levulose comparison (fig. 

 14-11) in which there exists a slight preponderance on the sucrose 

 side of the 45 degree line. When the two disaccharides, maltose 

 and sucrose, were compared, it was found that 87 per cent of the 

 strains fermented sucrose with greater ease. However, here as 

 elsewhere, a wide divergence of biochemical types was found. 

 Seven strains could not ferment sucrose at all but had little dif- 

 ficulty with maltose. 



RANGE OF VARIABILITY 



For a proper evaluation of the data presented, it is important 

 to realize that many of the strains examined in the present study 

 are haploid. The range of physiological behavior exhibited by any 

 family is thus conditioned not only by the types obtainable by seg- 

 regation and recombination of the segregant from the original par- 



