32 MORPHOLOGY AND CULTURE OF MICROORGANISMS. 



Their fermentative power is considerable, some of them being capable 

 of producing over 16 per cent by volume of alcohol. They differ in the 

 flavors and aromas which they produce in the fermented liquid, and especi- 

 ally in the rapidity with which they settle. Some yeasts, such as those of 

 Champagne and Burgundy, form a compact sediment which settles 



FIG. 14. Wine and beer yeasts. A, S. ellipsoideus, young and vigorous; B, S. 

 ellipsoideus, (i) old, (2) dead; C, S cerevisia, bottom yeast; D. S. cerevisia. top yeast. 

 (Original.) 



quickly and leaves the liquid clear. Others remain suspended for a long 

 time and settle with difficulty. 



Every region seems to have its own forms and the characteristics 

 of the various forms seem to be as well fixed as those of beer yeasts. 



Wines are manufactured by the use of these yeasts. They are 

 also employed in distilleries. In breweries they are considered disease 

 yezsts and have a deleterious effect on the beer. 



