FUNGI IMPERFECTI 179 



discharge from Oaks, produces abundant cell-chains on cultiva- 

 tion. S. apiculatus is very frequently met with on all kinds of 

 sweet fruits, it has orange-like cells. S. mycoderma has cylindri- 

 cal cells, often united together in chains (Fig. 183) : it forms a 

 whitish-gray mass (" fleur de vin ") on wine, beer, fruit-juice, etc., 

 standing in bottles uncorked or not entirely filled. It is thought 

 that this Fungus causes decomposition and oxydises the fluid in 

 which it is found, but it cannot produce alcoholic fermentation in 

 saccharine liquids, and it does not form endospores ; hence it is 

 uncertain whether it is true Saccharomyces. 



The "Dry-yeast" used in baking white bread is "surface- 



FIG. 181. Oidium lactis : a branched hypha commonly met with ; b a hypha lying in 

 milk and producing aerial hyphse which give rise to oidia ; c a branch giving rise to 

 oidia, the oldest (outermost) oidia are becoming detached from one another ; d a chain 

 of divided cells; e germinating oidia in different stages (slightly more magnified than the 

 other figures)/ 



yeast." In leaven, a kneaded mixture of meal, barm and water, 

 which is used for the manufacture of black bread, Saccharomyces 

 minor is present, and a species allied to this produces alcoholic 

 fermentation in dough with -the evolution of carbonic acid, which 

 causes the dough to "rise." 



2. Oidium-forms. Of many Fungi only the Oidium-forms 

 are known, which multiply in endless series without employing 

 any higher form of reproduction. Oidium lactis (Fig. 184) is an 

 imperfectly developed form which frequently appears on sour 



