8o 



BACTERIA, YEASTS, AND MOLDS 



Fig. 34. A yeast cell 

 containing four 

 spores. 



method of budding, but its contents break up into several 

 parts. In Fig. 34 is shown one of these yeast cells which 

 has been growing on a porcelain plate 

 without sufficient nourishment, and it 

 will be seen that four small bodies 

 have formed inside of the cell. These 

 bodies are spores and are capable of 

 resisting for a long time a variety of 

 adverse conditions, such as drying, 

 heating, etc., without being injured. 

 When the yeast cell breaks, the little spores burst forth 

 ready to be distributed by the winds or by any other 

 convenient means. 

 Not all species of 

 yeasts are yet 

 known to produce 

 spores of this kind, 

 although it is a 

 characteristic pos- 

 sessed by a large 

 number (Fig. 35). 

 Botanists divide 

 yeasts into two 

 divisions in accordance with their power of producing such 

 spores. The genus Saccharomyces includes yeasts which 

 produce spores, while the genus Torula includes those that 

 do not. The number of spores formed in a single yeast 

 cell is not always the same, although commonly three or 

 four. It may not always be the same for the same species 

 of yeast. 



Fig. 35. 



Three species of yeast each contain- 

 ing spores. 



