56 



FUNGOID DISEASES 



mushroom-like outgrowths called stromata (see 

 Fig. 15, B) with violet stalks and yellow heads. 



These heads contain numerous flask-like bodies 

 — perithecia — with the narrow part pointing out- 

 wards (see Fig. 15, C and D) and containing 

 numerous asci (spore cases). Each ascus encloses 



Fig. 15. — (A) Ryegrass affected with Claviceps purpiii'ca : (5) sclerotiuni ; 

 (B) germination of a sclerotium (s^) stroma ; (C) longitudinal section 

 through a stroma showing the perithecia (/>) containing asci ; (D) 

 perithecium more highly magnified showing the position of the asci 

 (a); (E) an ascus very highly magnified; (5) the ascospores. (After 

 Tulasne.) 



eight long, slender ascospores (Fig. 15, E). When 

 the ascospores are carried by the wind to the base 

 of the floret of the host plant, they send out a 

 germ tube which enters the ovary and produces at 

 the same time a mycelium externally bearing 

 numerous conidia. A sugary substance is secreted 



