206 MICRO-ORGANISMS AND FERMENTATION. 



SACCHAROMYCES HANSENII (ZOPF) 



was discovered by ZOPF among the fungi of cotton-seed flour. 

 It forms very small spherical spores, which usually develop 

 singly, and at most in pairs, in the mother-cell. It does 

 not induce alcoholic fermentation in fermentable nutrient 

 sugar solutions, but, 011 the other hand, crystals of calcium 

 oxalate have been observed in the sediment. ZOPF found such 

 crystals in nutrient solutions of galactose, grape-sugar, cane- 

 sugar, milk-sugar, maltose, dulcite, glycerine, and manriite. 



SACCHAROMYCES LUDWIGII (HANSEN). (Figs. 40, 41 and 60.) 



This remarkable species, which was discovered by LUDWIG in 

 the viscous secretion of the living oak, is the only one of the 

 known Saccharomycetes which can be recognised solely by means 

 of a microscopic examination. The following description is 

 taken from HANSEN'S investigations. The cells are very 

 variable in size, elliptical, bottle-shaped, sausage- or frequently 

 lemon-shaped. Partition walls may occur in all the complex 

 cell-combinations. The vegetative growths in wort-gelatine 

 are round like those of nearly all Saccliaromycetes, and are 

 either pale grey, or faintly yellow. In wort, it yields only 1*2 

 per cent, by volume of alcohol after a long continued fermentation; 

 and this accords with the fact that maltose is not fermented 

 by this species. In dextrose solutions, on the other hand, it 

 yields up to 10 per cent, by volume of alcohol. It inverts 

 saccharose, but does not ferment solutions of lactose and 

 dextrin, neither does it saccharify solutions of starch. It 

 readily develops spores in aqueous solutions of saccharose, in 

 wort-gelatine, in yeast-water, and in wort ; in the latter case, 

 even when no film has formed. 



It is characteristic of this species that, especially in the case 

 of young spores, a fusion of germinated spores often occurs, and 

 these new formations develop germ-filaments (promycelium), from 

 which new yeast-cells are gradually marked off by sharp trans- 

 verse septa. At the ends of these cells, buds develop, and 

 these again are marked off by transverse septa. 



