220 



MICRO-ORGANISMS AND FERMENTATION. 



develops mycelium. When this has attained a certain age, 

 it forms numerous, closely contiguous, transverse septa, and 

 gradually turns brown or olive green (5) ; this forms the 

 resting stage of the plant. In Hansen's air analyses, Dematium 

 was frequently found from spring until late autumn in wort 

 to which air had access. He observed that when the mould 

 was sown in a saccharine liquid it at first developed only 

 mycelial threads ; after some time, however, yeast-like cells 

 separated, without inducing alcoholic fermentation. 



P. Lindner states that one Dematium, species produces a 

 ropiness when cultivated in wort, owing to the formation of 

 slime from the cell membrane. Dematium species are also 

 found in milk and dairy products. A great development of 

 Dematium occurs in the sap which oozes from the cut stem of 

 the vine, and, according to Wortmann, this is the main reason 



Fig. .45. Dematium specie* (Jorgensen). Spore-formation in mycelial threads. 



why the sap is gradually converted into a slimy, gelatinous 

 mass. Wine must may also turn slimy, for the same 

 reason, if it is allowed to ferment too slowly. In isolated 

 cases Wortmann observed that Dematium exercises a destruc- 

 tive influence on grapes. The author observed in 1895 endo- 

 genous spore-formation in Dematium-like moulds occurring 

 on dried grapes, but the organism showed no development of 

 the resting cells described above (Fig. 45). The spores de- 

 veloped nothing but a yeast growth in saccharine liquids. 

 The yeast thus developed was capable of spore-formation, and 

 is, therefore, a true Saccharomyces. 



