ONION SMUT FUNGUS. 



109 



fact that it is hyaline while the sterile cells are brown. During the suc- 

 ceeding stages, however, it increases rapidly in size until it may be almost 

 as large as the spore itself (Fig. 1, K). This hemispherical or subglobose 



Fig. 1. — Gormiiuition of spores. 



vesicle corresponds to the promycelium or hemibasidium of other smuts 

 and rusts, and will be so designated. A stout tube grows out from the 

 surface of the promycelium (Fig. 1, C-G) and is quickly followed by 

 others in succession until a w^horl of diverging branches is produced (Fig. 

 1, H-N). The number of branches in the whorl is not constant, neither 



