214 MICRO-ORGANISMS AND FERMENTATION. 



temperature for the development of Monilia in wort are r 

 according to Hansen, maximum 42-43 C., and minimum 

 4-6 C. 



Many other species have been described, amongst which 

 may be mentioned M. sitophila, discovered by Went, which 

 grows on the earth nut (Arachis hypogaea) in West Java. Its 

 mycelium extends by degrees throughout the entire fruit, the 

 hypha3 assuming a yellow colour on exposure to air. By means 

 of the various enzymes which the fungus contains, a change is 

 brought about in the fruit contents. In this fermented con- 

 dition the earth nuts are eaten in large quantity by the natives. 

 Sachsia suaveolens, discovered by P. Lindner, is also an inter- 

 esting fungus belonging to this group. It produces a high 

 percentage of alcohol in wort, and develops a wine bouquet. 



6. Oidium lactis (Fig. 42). 



Oidium lactis is a mould which has played an important 

 part in the literature of the physiology of fermentation, and 

 in that of medicine. It is known as the milk mould. 



Some authors have sought to establish the theory that 

 this fungus is a stage in the development of species which, 

 under other circumstances, occur in entirely different forms,, 

 and with quite different properties. It was thus brought into- 

 genetic relation with Bacteria, Chalara, Saccharomyces, etc. 

 Both Brefeld and Hansen have carried out numerous investi- 

 gations with this fungus, and have undertaken culture ex- 

 periments, which were continued for a long time without 

 producing any other than the ordinary Oidium form. Recently, 

 it is true, Brefeld has discovered a formation of conidia re- 

 sembling chains of Oidium cells in several higher fungi, but it 

 has not yet been determined whether this also includes that 

 particular species which we designate Oidium lactis. 



The transparent, thin-walled hypha?, often forked and 

 branched, form a thick white felt ; in the upper part of the 

 filaments transverse septa are formed close together, after 

 which the single cells, filled with very refractive protoplasm, 

 are detached as conidia (Fig. 42: 3 to 7, 11 to 14, 17 to 19). 

 As a rule, the conidia, in longitudinal section, are rectangular 



