USTILAGO. 



277 



which at first swell up in a gelatinous manner. Spores are 

 formed inside the ultimate ramifications of the mycelium, and 

 as they reach maturity, the membrane loses' its gelatinous 

 character, the cells break up, and the spores are set free ; they 

 are dispersed as a dry dusty powder after rupture of the tissues 



\^^ 



Fig. 148. — Ustilago uiaydU. The head has liecu exposed to view by dissecting 

 away the enclosing leaves; it is beset towards the apex by smut-boils. 

 (V. Tubeuf phot.) 



of the host enclosing them. The spores germinate, giving rise 

 to a promycelium (basidium), which becomes divided up by 

 means of cross-septa into several cells, from each of which 

 conidia are laterally abjointed. These conidia sprout yeast- 

 like, and give off new conidia, or they produce a mycelium ; 



