YEAST 



31 



the parent cell, and may even bud in turn, thus giving rise to 

 chains of yeast cells (Fig. 14). 



Spore-formation. Another mode of reproduction occurs 

 under certain and for the most part unknown conditions. 

 The protoplasm divides, within the cellulose membrane, to 

 form two, three, or four compact, rounded spores (Fig. 15). 

 Under favorable conditions the spore capsules burst or sprout, 

 and the spores emerge as yeast cells which then develop like 



FIG. 14. Colonies of budding yeast cells. (From Sedgwick and Wilson.) 



ordinary forms. Reproduction by this means is called endo- 

 genous sporulation, which differs somewhat from "spore- 

 formation" in bacteria where there may be no actual reproduc- 

 tion but merely a temporary protection against drying, or 

 other unfavorable condition of the environment. 



Culture Media. The simplicity of structure of yeast cells 

 would naturally suggest a simplification of the vital processes, 

 and lend support to the belief that these might be more readily 



