TAXONOMY 
255 
mences to form on the parent-cell. This grows larger and a portion 
of the cytoplasm and nuclear material pass into it. Eventually a 
daughter-bud, which may assume the size of the parent-cell, is 
formed. This generally adheres to the parent-cell and produces one 
or more granddaughter-buds which in turn may produce great-grand¬ 
daughter-buds before separation from the parent-cell takes place. 
There are two varieties of brewer’s yeast, viz.: Top yeasts and 
Bottom yeasts. Top yeasts grow on or near the surface of the liquid 
Fig. 128 .—Saccharomyces ellipsoideus. A common yeast found on grapes, 
jams, jellies, etc. Budding process is shown in many of the cells as also the vac¬ 
uoles. ( Schneider , Pharmaceutical Bacteriology.) 
and produce rapid fermentation at summer temperatures causing 
great quantities of carbon dioxide to arise to the surface and thus 
forming the froth which is characteristic of ale, stout and porter. 
Bottom yeasts grow at about 4°C. at or near the bottom of the 
vat. They are used in the manufacture of lager beers. 
Compressed yeast (Cerevisiae Fermentum Compressum) N. F. 
consists of the moist, living cells of Saccharomyces cerevisice or of other 
species of Saccharomyces, combined with a starchy or absorbent 
base. 
