240 MICRO-ORGANISMS AND FERMENTATION. 



ferment maltose, and neither ferments nor inverts cane-sugar 

 In 10 per cent, and 15 per cent, solutions of dextrose in 

 yeast-water it gives 4*6 and 4' 5 per cent, by volume of alcohol 

 after 15 days at 25 C., and 4*8 and 4'7 per cent, in 28 days. 

 In two other flasks 4'8 and 5 '3 per cent, of alcohol had been 

 produced after long standing. HANSEN assumes that this 

 species takes part in vinous fermentation, and considers it 

 probable that species such as the sixth and seventh, which 

 produce a vigorous fermentation in dextrose solutions, take part 

 in the fermentation of grape-juice and other fruits. On the 

 other hand they have probably little importance in breweries 

 and distilleries, since they are unable to ferment maltose. 



Another species of Torula (Torula Novce Carlsbergice}, the 

 cells of which exhibit very different forms, has been described 

 by GROENLUND. It imparts a disagreeable bitter taste to wort. 

 According to SCHJERNING'S investigations it inverts cane-sugar, 

 and induces alcoholic fermentation in solutions of cane-sugar, 

 dextrose, and maltose. In ordinary brewery-wort it can 

 produce about 4*7 per cent, (volume) of alcohol. 



Torula species which contain no invertase, yield only about 

 1 per cent, (volume) of alcohol, and do not ferment maltose, 

 are found widely distributed in nature. Those which have 

 been examined ferment solutions of dextrose. 



Belated to the above are the red budding -fungi (the "pink 

 yeast " of medicinal bacteriology) universally distributed in 

 atmospheric dust; several species of these are known. KRAMER, 

 for instance, found in must a top-fermentation torula-yeast 

 which produces a red colouring-matter soluble in water. It 

 ferments dextrose, and, in a 10 per cent, solution, it yields 4'5 

 per cent, by volume of alcohol ; it inverts cane-sugar, directly 

 ferments maltose, but has no action on lactose. 



These different species cannot be distinguished by the 

 microscope alone either from each other or from the round 

 cells of the Saccharomycetes, and, as seen above, there are 

 species with pronounced fermentative activity. 



HANSEN assumes, with some degree of probability, that they 

 are derived from the higher fungi, and in his cultivation 

 experiments he has observed the development of a mycelium- 

 in a few cases. 



