PHARMACEUTICAL BOTANY 
2 54 
processes, and becoming dormant. Sometimes they enter the rest¬ 
ing condition after a process of division, when each cell divides into 
four parts, each of which becomes nearly dry and is surrounded by a 
thick wall. Such cells are called ascospores , and their production 
serves both as a method of multiplying the plant and of tiding over 
adverse conditions. They can survive for a long time without 
food or water, and can endure higher temperatures than the active 
cells and almost any degree of cold. 
Fig. 127. —Saccharomyces cerevisice. The form or variety known as brewers' top 
yeast. ( Oberhefe .) 
The dried cells and spores float in the air as dust and so accomplish 
a dispersal of the organism. Doubtless most of them never again 
meet suitable environment and so sooner or later perish. But some 
will fall into favorable conditions and be able to multiply enormously 
again, and so the species is continued. 
The general method of reproduction in Saccharomyces is that of 
gemmation or budding . A small protuberance of the cell wall com- 
