102 



BACTERIA AND FERMENTATION 



Saccharomyces Ellipsoidus I. Round, oval, or sausage-shaped cells, single or in 

 chains; ascospores in twenty-four hours at 25 C. (not above 30 C. , not below 

 4 C.). Grown on the surface of wort gelatine, a network is produced by which 

 they can be recognised (in eight to twelve days at 33 C.). At 13-15" C. a 

 characteristic branching mass is produced. It is an alcoholic ferment as active as 



O 00 



FIG. 15. Diagram of S. cerevisite. 



FIG. 16. Diagram of S. cllipsoideus. 



S. cerevisice. S. ellipsoideus II. Round and oval, rarely elongated, a widely dis- 

 tributed yeast, causing ** muddiness " in beer and a bitter taste. It is essentially a 

 " low " yeast, and one of the so-called " wild yeasts " injurious to beer. 



Saccharomyces Conglomerate is a round cell, often united in clusters, and 

 occurring in rotting grapes, and at the commencement of fermentation. 



Saccharomyces Pastorianus I. Oval or club-shaped cells, occurring in after- 

 fermentation of wine, etc., and producing a bitter taste, unpleasant odour, and 

 turbidity. The spores frequently occur in the air of 

 breweries. 



S. Pastor. II. Elongated cells, possessing an in- 

 vertose ferment. They do not, like S. pastor. I., 

 produce disease in beer. 



S. Pastor. 111. Oval or elongated cells, producing 

 turbidity in beer. Grown on yeast-water gelatine ; 

 the colonies show after sixteen days crenated hairy 

 edges. 



Saccharomyces Apiculatus. Lemon-shaped cells. 

 They give rise to a feeble alcoholic fermentation, and 

 produce two kinds of spores round and oval ; they 

 appear at the onset of vinous fermentation, but give 

 way later on to S. cerevisice. 



Saccharomyces Mycoderma. Oval or elliptical cells, 

 often in branching 'chains. They form the so-called 

 "mould" on fermented liquids, and develop on the 

 surface without exciting fermentation. When forced to grow submerged, they 

 produce a little alcohol. 



Saccharomyces Exiyuus. Conical cells, appearing in the after-fermentation of 

 beer. 



Saccharomyces Pyriformis.Oval cells, converting sugary solutions containing 

 ginger into ginger-beer. 



Saccharomyces lllicis, Hansenii, and Aquifolii produce a small percentage of 

 alcohol. 



2. Acetous Fermentation 



Cause, Mycoderma aceti ; medium, wine and other alcoholic liquids; result, the 



formation of vinegar. 



If alcohol be diluted with water, and the specific ferment mixed 

 with it and exposed to the air at 22 C., it is rapidly converted into 



FIG. 17. Diagram of S. 

 pastorianus. 



