IMPORTANCE IN WINE-MAKING. 441 



wines are those in which the number of elliptical yeasfc cells in 

 the sowing was high in comparison with those of the apiculate 

 cells. 



The collaboration of Sacch. apiculatus in the fermentation of 

 wine is always a drawback, not merely because fermentation is 

 retarded, the fixed acids destroyed in an uncontrollable manner 

 (and one that may proceed too far in certain beverages that, are 

 low in acid), and volatile acids and other malodorous and bad 

 flavoured products, or such (esters, &c.) that may alter the 

 character of the beverage, are formed ; but also because in 

 many instances the attenuation is unsatisfactory. For example, 

 MULLER-THURGAU (XVI.) has found that both fruit and grape 

 wines fermented with an elliptical wine yeast and a race of 

 Apiculatus mostly contain a large residue of unfermented sugars of 

 the kind the latter yeast cannot attack. In the case of the experi- 

 ments detailed on p. 437, vol. ii., the amount of these sugars left 

 in a grape wine at the close of primary fermentation was 10 per 

 cent, with Sacch. apiculatus. 0.05 per cent, with Steinberg yeast, 

 0.075 per cent, with Steinberg and Sacch. apiculatus, 0.189 F er ceru ^ 

 with Karthaus yeast, and 0.396 per cent, with Karthaus and 

 /Sacch. apiculatus. Moreover, it is well known that wines low in 

 alcohol are more liable to maladies like turning (acetic taint), and 

 more especially ropiness, when they also contain an appreciable 

 residuum of sugar capable of furnishing the corresponding patho- 

 genic organisms with material for nourishment or fermentation. 



The wine and fruit wine industries are in the unpleasant 

 position of having to make the best of the presence of Sacch. 

 apiculatus. In the case of apples and pears a large proportion 

 of the indigenous yeast can be removed by washing, but this is 

 impracticable, for several reasons, with berries and especially with 

 grapes. The purification of grape must by filtering or centri- 

 f ugalising is attended with insuperable difficulties at present, and 

 pasteurisation is mostly impracticable under the existing con- 

 ditions of the wine industry. On the other hand, the growing 

 employment of pure culture wine yeasts affords a suitable means 

 for rapidly suppressing the injurious influence of the /Sacch. apicu- 

 latus present in the indigenous yeast. Whenever it is anticipated 

 that fruit must will be strongly infected with the pest, or the 

 presence of the latter has been discovered in the microscopical 

 examination of grapes or the freshly expressed juice of same, it 

 is advisable to employ more than the usual quantity of pure 

 yeast, and to add it to the must as early as possible. In making 

 cider and perry the fermentation of the beverage will be purer 

 and the content of volatile acids smaller if the fruit be washed 

 thoroughly before putting it through the mill, and the juice be 

 then pitched with a sufficient quantity of vigorous pure yeast. 

 Even in these circumstances Sacch. apiculatus will have some 

 opportunity during the must stage and at the commencement of 



