ALCOHOLIC FERMENTS. 193 



species. The cells are 1'5 to 2'5 p in diameter, and almost 

 spherical. According to Duclaux's experiments, this yeast 

 is more aerobic than the ordinary alcoholic yeasts. Even 

 with strong aeration of the liquid, the whole of the milk- 

 sugar is used up in the alcoholic fermentation. In a 5 

 per cent, solution of milk-sugar 2*5 per cent, of alcohol 

 was formed in eleven days at 25 C. The most favourable 

 temperature for the fermentation of a neutral solution is 25 

 to 32 C., whilst at 37 to 40 C. the fermentation ceases. 

 Small quantities of acid have a retarding influence on 

 the fermentative activity of this yeast. 



Adametz likewise describes a budding-fungus which 

 ferments milk-sugar. Since this fungus does not yield 

 endogenous spores by Hansen's method, it is classed in the 

 group of non-Saccharomycetes. The cells are of about the 

 same size as those of Saccharomyces cerevisice, and are 

 spherical and elliptical. The colonies grown on peptone- 

 gelatine are round with slightly jagged borders and are of 

 a dark brown colour. A puncture-cultivation in wort- 

 gelatine yields a dull, flat mass on the surface and a 

 vigorous growth in the punctured channel, and from this 

 numerous rays penetrate into the gelatine. In sterilised 

 milk, this fungus induces fermentation phenomena within 

 24 hours at 50 C., in 48 hours at 38 C., and in about 

 four days at 25 C. In this fermentation, the milk-sugar 

 is alone decomposed. 



Both of the species mentioned above have been more 

 closely investigated by Kayser, together with a ne^v species 

 which likewise ferments lactose and also belongs to the 

 non-Saccharomycetes. All three yield colonies on gelatine, 

 which are more spread out than those of beer- and wine- 

 yeasts ; in the middle of the colonies there is a thicker 

 portion, whilst the border resembles mycelium. In milk 

 and in neutral liquids, when sufficiently aerated, they 

 induce an appreciable fermentation at 25 to 30 C. The 

 milk does not coagulate or become viscous during the 



