ALCOHOLIC FERMENTS. 147 



cerevisice (page 200) can neither invert nor ferment the 

 above four carbohydrates. 1 



Sacch. apiculatus (page 195) does not invert saccharose, 

 and of the four sugars mentioned it only ferments dextrose. 

 It therefore only induces a feeble alcoholic fermentation in 

 beer wort. 



Amongst the Torula forms (page 189) examined by 

 Hansen there are many which do not secrete invertase, do 

 not ferment maltose, and which only yield about 1 per cent, 

 of alcohol (by volume) in beer wort. Other species invert 

 saccharose. In nutritive dextrose solutions the different 

 species induce a more or less vigorous fermentation. 



Monilia Candida (page 100) possesses no invertive action, 

 but ferments saccharose (without hydrolysing it), maltose, 

 and dextrose. It ferments beer-wort, but at the ordinary 

 room-temperature it only very slowly yields the higher per- 

 centages of alcohol, as compared with the Sacckaromycetes. 



If we now review all these different properties of the 

 Saccharomycetes we shall see that they fall into two 

 groups : 



I. Those which develop invertase, and induce alcoholic 



fermentation. This group is further sub-divided into 

 (a) those which not only ferment saccharose and 

 dextrose, but also vigorously ferment maltose 

 (Hansen's first described six species, and the 

 yeasts employed in the brewing industry). 

 (6) those which ferment saccharose and dextrose, but 

 not maltose (Sacch. Marxianus, Ludiuigii and 

 exiguus). 



II. Those which do not develop invertase, and do not induce 

 alcoholic fermentation (Sacch. rnembranaefaciens). 



The budding fungi ivhich do not form endospores (non- 

 Saccharomycetes) show, with reference to the properties of 

 inversion and fermentation, the most varied characters. 



1 According to Lasches experiments, some species of Mycoderma 

 present in beer are capable of inducing alcoholic fermentation. 



