SACCHAROMYCES BEHRENSIANUS 229 



unite two by two. This fusion almost always operates between two 

 ascospores from the same asc, exceptionally between two spores from 

 closely situated ascs. A canal for copulation is formed through 

 which the contents fuse. The fusion takes place, the copulation canal 

 gives birth to a sort of germinating tube which enlarges and takes the 

 shape of a vegetative cell ; it finally cuts itself off from the canal by 

 a wall accompanied by a circular construction. (Fig. 36.) The cell 

 thus formed separates from the zygospore which continues to form 

 new cells by the same process. The fusion of the ascospores is gen- 

 erally not absolute and quite a number among them germinate alone. 



We have observed, as has been stated, a species of Saccharomyces 

 Ludwigii from Hansen's laboratory which, having remained for a time 

 at laboratory temperature, had completely lost its sexuality. The 

 ascospores always developed without fusing. 



Hansen has shown that when various cells are cultivated from a 

 colony of this yeast, a sporogenic and an asporogenic race may be 

 obtained. 



On wort gelatin, Saccharomyces Ludwigii develops in the shape of 

 vegetative spots in which the color varies from a clear gray to a pale 

 yellow. In beer wort, it produces at the end of about a month, at 

 room temperature, a scum with elongated colonies. 



It yields even after a fermentation of long duration, only 1.2 per 

 cent of alcohol by volume. It does not act on maltose. On the other 

 hand in glucose about 10 per cent of alcohol is produced. It inverts 

 saccharose, and ferments dextrose, d-galactose, d-mannose, levulose, 

 raffinose, and sometimes very slightly, 1-sorbose, and tagatose (Lind- 

 ner). It has no action on lactose or maltose. 



SACCHAROMYCES BEHRENSIANUS. (Behrens) 



This yeast, discovered by Behrens l on hops, possesses round or 

 oval cells which divide like those of Saccharomyces Ludwigii. The 

 optimum temperature for sporulation is from 18 to 20 C.; at this 

 temperature, the ascospores appear in about 22 hours. The asco- 

 spores are spherical (4 to 4.5/>t in diameter) and are to the number of 

 two or three in an asc. Their germination is accomplished as in Sac- 

 charomyces Ludwigii. This yeast produces no scum. On 10 per 

 cent wort gelatin, the giant colonies present quite a characteristic 

 appearance. They show fine concentric rings placed around a cra- 

 teriform cavity which makes up the center. The edge of the colonies 

 is of a pure white and the middle portions of a yellow color. In 



1 Behrens, J. Studien iiber die Konswevierung und Zusammensetzung des 

 Hopfens. Woch. f. Brau. 13, 1896. 



