ALCOHOLIC FERMENTS. 



213 



curious cell-forms (Fig. 64 a) occur, which also develop during 

 fermentation. In wort-cultures five months old no film had 

 developed ; only a yeast-ring was observed. The liquor is not 

 decolourised by old cultures. 



The spores (Fig. 65) are usually oval. They occur in all 

 cell-forms, generally four to a cell ; they refract light strongly, 

 and, according to HOLM, they are coloured blue by iodine. 



In plate- and streak-cultures, the growths, both on and 

 below the surface, have a sharp cut edge ; the cell-forms are 

 similar to those in liquids ; cells shaped like the conidia of 

 O'idium lactis frequently occur. 



FIG. 65. Saccharomyces mellacei. Vegetation from the yeast-ring in beer- wort. 



(HOLM.) 



According to investigations made by P. GREG in the author's 

 laboratory, divergencies of a marked and permanent character 

 distinguish the species belonging to this type. Thus some 

 yield malodorous products in the fermenting liquor, others 

 differ greatly in the length of time required to complete 

 the fermentation in one and the same sterilised molasses and 

 under identical conditions. The amount of alcohol produced 

 by these types varied from 6 '6 to 7 '6 per cent, by volume. 

 The rate of multiplying also differed widely in these species. 

 Further details relating to comparative results in practice are 

 given in papers by GREG and by HART, who has carried out 

 rum-fermentation with ellipsoidal species. 



