UBTILAQINEJE. 



321 



there grow out small sporidia, which germinate by sending 

 out a slender hypha ; when this hypha comes in contact 

 with the proper host plant, it penetrates the walls of its 





Fig. Z24. TtUetia caries, d, transverse section of an infected wheat-grain ; e, ripe 

 spore ; /, the flret stage of germination ; g, the formation of a branching promyce- 

 lium, with granular protoplasm in its upper end ; h, the formation of slender 

 branches which unite by a kind of conjugation ; the ends of these branches give rise 

 somewhat later to very small sporidia, and when thece germinate very sleudtr hy- 

 phae are produced, which penetrate the epidermis as at i ; k', mycelium from the 

 young ovary of the wheat two small lateral branches are shown, from which spores 

 will develop ; k, spores more fully developed. d, after (Ersted ; e-h, after Tulasne, 

 X 460 ; i-k, after Kuhn, x 300. 



cells, and thus gains admittance to its interior, where it pro- 

 duces a new mycelium* (Fig. 224, t). In Ustilago carbo the 



* This is upon the authority of Kuhn : " Krankheiten der Culturg-e- 

 wachse," 1859. There are some doubta as to the correctness of his 

 observations, and they have not been confirmed bv any one. 



