Cold *nd 



Yeasts 



42 HOUSEHOLD BACTERIOLOGY. 



working by the yeast means no possible raising of the 

 dough by the gas. Sometimes the dried yeast cake 

 has been carelessly prepared in this respect and the 

 yeast plants are nearly all dead. 



The yeast plants can endure cold better than heat. 



FIG. 24. YEAST PLANTS IN VARIOUS STAGES OF BUDDING OR 

 REPRODUCTION". (After Sedgwick and Wilson.) 



Experiment 

 with Yeasts 



It hinders their work but does not quickly kill them. 

 To show the favorable or unfavorable tempera- 

 ture for the growth of yeast plants, take one-half 

 cup each of boiling, lukewarm and ice-cold water. 

 Add to each one tablespoonful of molasses and one- 



