VARIATION OF. SPECIES 183 



and, for example, employing a solution made up of peptone, maltose, 

 and various salts or a must gelatin, that the composition of the 

 medium does not play any role in this transformation. The same 

 is true for aeration of the culture. The only factor which seems to 

 have any effect is the temperature. 



The formation of sporogenic and asporogenic types of yeast in the 

 same culture of yeast seems rather common. Nadson, rather recently, 

 has observed asporogenic varieties in Nadsonia fulvescens. The col- 

 onies of this type have a white color which distinguishes them from 

 the sporogenic colonies which are reddish. 



Saito has noticed in Zygosaccharomyces Mandshuricus the forma- 

 tion of asporogenic types, indicated by a transparent yellow color, while 

 the sporogenic types have a white color. The asporogenic type ap- 

 pears as a mutation. If the white colonies are isolated both sporo- 

 genic and asporogenic colonies are obtained. When the asporogenic 

 colonies are isolated, one obtains, almost exclusively, asporo- 

 genic yellow colonies. There seems to be a tendency to return to the 

 sporogenic type as is shown by other data. The sporogenic type 

 is distinguished from the asporogenic type by a certain number of 

 characteristics. The asporogenic type contains but a small amount 

 of glycogen. Their reaction towards Lugol's iodine allows them to be 

 distinguished macroscopically. On the other hand the asporogenic 

 variety liquefies gelatin while the sporogenic race does not. The 

 sporogenic type forms a deposit of spherical cells at from 28 to 

 30 while the other type forms long cells sometimes in chains. 



This ic contrary to the observations of Hansen on S. pastorianus 

 and the yeast Johannisberg II, in which the sporogenic race was only 

 slightly formed; in S. mandshuricus, as in Sch. octosporus and Nad- 

 sonia, the asporogenic varieties appeared quickly and do not seem to 

 depend on conditions of culturing but on internal conditions. A low 

 temperature, however, as in Schizosaccharomyces octosporus., favors the 

 formation of asporogenic races, and in old cultures the asporogenic 

 types seem to predominate. 



Saito has also observed the formation of asporogenic races in 

 Zygosaccharomyces Mandshuricus. There are white colonies and gray- 

 ish yellow colonies with irregular surfaces. The inoculation of a white 

 colony produces a majority of white colonies with a few yellow 

 colonies. The inoculation of grayish yellow colonies gives the asporo- 

 genic cells. The asporogenic race is distinguished from the sporo- 

 genic race by the shape of its cells, longer and arranged in chains 

 with less glycogen. The white race which is not definitely asporogenic 

 has a tendency to lose its sexuality and to give parthenogenetic ascs 

 after unfruitful attempts at copulation. 



