YEASTS. 41 



sible the raised bread, or the- "election cake" like that 

 of our grandmother's time ; it also produces the 

 "froth" and '"sparkle" of the "home-made spruce beer" 

 as well as that of the large breweries. 



Yeast plants grow best from 70 F. to 90 F. They 



FIG. 23. A YEAST GARDEN. 



do not work well under 70 F. and are killed when in 

 a moist state by the temperature of 130-! 50 F. No 

 wonder the bread will not rise when the cook pours 

 boiling or even hot water on the cake of yeast! Dead 

 plants cannot work any more than dead animals. No 



Favorable 

 Temperature 



