SAC FUNGI IN PARTICULAR 



39 



Starter began in Roman times, but the art was lost until the seventeenth 

 century, when it was regained. One of the earliest methods of obtain- 

 ing yeast was salt raising, which consisted in adding to a quantity of 

 milk a little salt sufficient to delay the growth of bacteria, while the 

 yeast found entrance to the milk through the air and grew rapidly. 

 This milk was then mixed with dough for the raising process. Bakers 

 also sometimes used a brew called barms. Scotch barms were prepared 

 by taking hops and flour with other ingredients which were allowed to 



^ '^^ ^ ^^^ 

 C^^^ 



Fig. 48. — Saccharomyces ellipsoideus. A common yeast in jams, jellies, etc. 

 Budding process is shown in many of the cells as also the vacuoles. Fig. 66, p. 145, 

 Schneider, Pharmaceutical Bacteriology, 1912. 



ferment spontaneously, and the fermented material was used in 

 bread baking (see page 667). 



Saccharomyces ellipsoideus (Fig. 48) is known as the wine yeast and 

 may be classed as a wild species, while the beer yeast is found only in 

 cultivation. The vegetative cells are ellipsoidal 6/x long, single, or 

 united into a row of loosely connected cells. The cells are two- to four- 

 spored. The spores are spheric 2 to 4/i broad. It is important in the 

 fermentation of grape juice, gaining entrance from the skin of the 

 grape fruit upon which it lives. In the spore form, it overwinters in 

 the soil, being blown as dust to the developing grape fruits. The 



