436 SACCHAROMYCES APICULATUS. 



produce acetic ether, more particularly when the nutrient solution 

 is aerated continuously. According to SCHANDER (III.), some 

 races of Sacch. apiculatus are to be numbered among the yeasts 

 that produce sulphuretted hydrogen, and its accompanying dis- 

 agreeable taste, in wine. 



As another metabolic peculiarity may be mentioned HENNE- 

 BEKG'S (VI.) discovery that the cells of this yeast are only able to 

 store up small quantities of glycogen. On the other hand, the 

 abundant secretion of proteolytic enzymes is demonstrated by 

 the rapid liquefaction of gelatin in cultures of various Apiculatus 

 yeasts. Finally, AMTHOR (I.) mentions, as a special property of 

 these budding fungi, that it exerts a powerful decolorising action 

 when employed to ferment wine must, which observation was 

 confirmed by SCHANDER (II.) in the case of the races examined by 

 him. 



313. The Importance of Saceharomyces apiculatus 

 in Wine-making 1 . 



REESS (I.) found Sacch. apiculatus to be a constant member of 

 the abundant fungoid flora on ripe grapes and fruit ; and this 

 discovery has since been confirmed by PASTEUR (XXVIII.) and 

 numerous other workers. HANSEN (IX.), in his researches on 

 the life cycle of yeasts, showed whence and how this yeast finds 

 its way on to grapes, the easily recognisable cell form of Sacch. 

 apiculatus being specially adapted for this purpose. The particulars 

 have already been given in 271. Cells of Sacch. apiculatus are 

 only found occasionally on unripe fruit, on which they soon perish, 

 owing to the unfavourable conditions, especially drought ; but as 

 the fruit ripens, the conditions of existence become more suitable 

 for the fungus. It is first found on cherries, these ripening 

 earlier than any other fruit (in Central Europe) ; soon afterwards 

 it is met with on gooseberries and currants, then on plums, and, 

 finally, on grapes. Strawberries, raspberries, and sorb apples 

 come in in their proper turn. Where two kinds of fruit that 

 ripen at different times are met with, even side by side, such as 

 currants and grapes, only the earlier one will be found infested 

 with the fungus at first, the other exhibiting none at all or only 

 a few isolated cells. Thus, in a vineyard at Geisenheim-on- 

 Rhine, where a plantation of early Burgundy grapes lay side by 

 side with one of late grapes of the same class, MULLER-THUR- 

 GAU (XXVI.) observed on August 23 large numbers of yeast cells 

 on the earlier grapes, that werv just ripe, whereas none could be 

 found on the adjoining (unripe) late grapes. Apart from the fact 

 that the wind-borne yeast cells found a more suitable habitat on 

 the ripe grapes, and were able to reproduce extensively thereon, 

 especially when they could gain access to the juice through any 



aperture, it is certain that as discovered by Miiller-Thurgau a 



considerable part is played by insects, which prefer ripe fruit, and, 



