30G MICRO-ORGANISMS AND FERMENTATION. 



case of a wine yeast (Johannisberg II.). He placed spore- 

 forming cells in a shallow layer of wort. In the course of a 

 few hours they swelled up and burst the mother-cells. They 

 were then transferred to a shallow layer in a saturated aqueous 

 solution of calcium sulphate at 25 C. Under these conditions 

 no budding took place, but several spores fused together and 

 formed new endospores. Similarly, Guilliermond detected a 

 fusion of spores in S. Ludwigii. 



In this connection we may mention the fusion (copulation) 

 of vegetative cells observed by Schionning, Guilliermond, and 

 Barker, in the case of S. octosporus, Pombe, mellacei, and 

 Zygosaccharomyces. Further details are given in the systematic 

 description of these species. 



The germination of the spores of the known species of the 

 groups S. Pastorianus and S. ellipsoideus takes place in essen- 

 tially the same way as that just described. 



S. Ludwigii forms a second and very different type (Figs. 

 55, 56), where germination does not take place through budding, 

 but through a germinal tube, called a promycelium. Two 

 such germinal tubes frequently fuse together, and the propa- 

 gation of yeast cells takes place through division and not 

 through budding, after the formation of a clearly defined 

 septum. Similarly these yeast cells produce new cells. In 

 this case, unlike the first type, it is not the spores, but the 

 new formations springing from them that fuse together. 

 Guilliermond observed such a fusion of germinal tubes in 

 spores which were derived from different mother cells. 



In older spores this curious fusion is more uncommon 

 (Fig. 56). A few germ-filaments develop into a branched 

 mycelium (group b). 



The spores of S. anomalus have a remarkable shape similar 

 to those of Endomyces decipiens* They are almost hemi- 

 spherical with a rim round the base. 



During germination the spores swell and the projecting 

 rims may either remain or disappear. Buds then crop out 

 at different points on the surface of the spore. 



* A fungus which is parasitic on the lamellae of certain mushrooms. A similar 

 species was described by P. Lindner as E. fibuliger. 



