192 MICRO-ORGANISMS AND FERMENTATION. 



the cells of which exhibit very different forms, has been 

 described by Gronlund. 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. 



Eelated to the above are the red-coloured budding-fungi 

 (the pink yeast of medicinal bacteriology) universally dis- 

 tributed in atmospheric dust ; several species of these are 

 known ; Kramer, for instance, found in must a top-fermen- 

 tation 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. Pasteur distinguished the 

 Torula-forms from the other yeasts, because the species 

 which he examined excited only a very feeble alcoholic 

 fermentation. It will be seen, however, from the above 

 that there are also species with pronounced fermentative 

 activity. 



Hansen assumes with some degree of probability that 

 they are derived from the higher fungi, and in his cultiva- 

 tion experiments he has, as mentioned above, in a few cases 

 observed the development of a mycelium,. 



Duclaux found a yeast-fungus in milk \vhich . induces 

 alcoholic fermentation in a solution of lactose. A con- 

 version of lactose into galactose was not observed. This 

 fungus appears to be most closely related to the Torula 



