SACCHAROMYCES, HANSENIA, TORULASPORA. 283 



colonies on gelatin are yellow in colour, and rapidly liquefy the 

 substratum, which they cover with a yellow film. The same 

 appearance is also observed in the sowings on milk and on solutions 

 of lactose. The yellow colouring-matter is formed only in presence 

 of air. The species was discovered in butter, to which it had 

 imparted an abnormal yellow colour and a highly disagreeable 

 smell like stale urine. It is included here on account of the 

 remarkable production of colouring-matter, although only imper- 

 fectly described at present. 



The species of the fifth sub-group are characterised by their 

 power of fermenting lactose. Hence they belong to the organisms 

 which excite alcoholic fermentation in milk (see vol. i. p. 85) and 

 play an important part in the preparation of Kefyr, Koumiss, 

 Mazun, &c. They are but few in number. A species of budding 

 fungus discovered in milk by GROTENFELT (III.) was named by him 

 Sacch. acidi lactici (not S. lactis acidi as is frequently, but errone- 

 ously, written). In respect of this species, and of another pre- 

 viously, described by DUCLAUX (XIV.) and named Sacch. lactis, he 

 says that both sporulate on potatoes. Kayser afterwards showed 

 that Duclaux's species cannot produce spores and is therefore a 

 torula ; consequently it is also highly probable that Grotenfelt's 

 species is not a Saccfiaromyces. A number of other species also 

 described as Sacckaromyces are really tor ulse (see chap. lix.). On 

 the other hand, the following species must be classed as true 

 Saccharomycetes : a Saccharomyces capable of fermenting lactose, 

 discovered by E. vox FREUDENREICH and O JENSEN (II.) in 

 Emmenthal cheese ; two species afterwards isolated from butter 

 by 0. JENSEN (II.), and one found by MAZE (I.) in cheese. None 

 of them has received a systematic name, and the descriptions are 

 imperfect. 



The only species of which a complete description is available 

 and to which a systematic name has been given is the following : 



Saccharomyces fragilis, JORGENSEN, which has been drawn by 

 that worker (XIII.). The cells are small, oval, and elongated. 

 The spheroidal spores are proiuced both in fermenting liquids on 

 gelatin, and in gypsum-block cultures, appearing in the latter 

 case after twenty hours at 25C., and in forty hours at 15 C. 

 Grown in 10 per cent, lactose yeast water at room temperature, 

 the species produces i per cent, (by weight) of alcohol in eight 

 days, and 4 per cent, in four months ; whilst in wort of the 

 gravity 1 1 per cent. Balling, it produces about i per cent, of 

 alcohol in ten days at room temperature. The species was isolated 

 from Kefyr. 



The sixth sub-group of the Saccharomycetes is characterised by 

 lacking the faculty of exciting alcoholic fermentation. The only 

 representative known as yet is : 



Saccharomyces Hansenii, ZOPF (XIII.). The cells are globular 

 to ellipsoidal and measure 4-11/1 in diameter. Each cell contains 



