BARBER: HEREDITY IN CERTAIN MICRO-ORGANISMS. 5 



ducing alcoholic fermentation, A type of S. c^revisise pro- 

 duced one to three volumes per cent, more alcohol than the 

 parent form from which it was derived. 



Other strains differed from their types in their power of 

 forming invertase and maltase. A race of S. pastorianus I for 

 some time failed to impart to beer a bitter taste and disa- 

 greeable odor characteristic of the type ; and variations of 

 other types having to do with the clarification of beer and 

 other aspects of brewing are mentioned by the author. 



These physiological types originated for the most part in 

 changed conditions of cultivation. For instance, Biernacki 

 and, later, Miircker, Haydruck and Effront have found that 

 the addition of small quantities of antiseptics to cultures of 

 certain yeasts may increase their fermentative power. But 

 Hansen is of the opinion that in some of these cases, at least, 

 we have to do with a selection of cells endowed with certain 

 physiological characteristics and not with mere transforma- 

 tion. The relative weight of these two factors in such ex- 

 periments is a matter hard to determine. 



M. W. Beijerinck (1897) isolated from a species of Schizo- 

 saccharomyces found on fruits of tropical origin two sorts of 

 colonies on wort gelatin. One sort, brown in color, was 

 asporogenous ; the other, which was white, produced spores, 

 and intermediate forms occurred. On testing the offspring 

 of these colonies, the white variety was found to give nearly 

 all white colonies ; the brown gave brown ; while the inter- 

 mediate types gave both white and brown. Certain morpho- 

 logical and physiological differences were also characteristic 

 of the different races. The brown, for instance, divide with- 

 out forming the characteristic "yokes." The asporogenous 

 race showed a loss of power of producing trypsin. There 

 was little difference in fermentative power, but the chief fer- 

 mentation was most marked in the spore-bearing form ; the 

 secondary, in the asporogenous type. 



In Schizosaccharomyces pombe this author found white and 

 brown colonies, one of which was more productive of spores 

 than the other. In S. asporus he found white colonies with 

 thick, short cells, and brown colonies with similar cells, but 

 having in addition long, thin ones. He found this same 



