284 



A TEXTBOOK OF THEORETICAL BOTANY 



The former functions as an ascogonium, the latter as an antheridium. 



On the side of the ascogonium nearest to the antheridium, a papilla is 



formed, the wall dissolves and the nuclei 

 of the antheridium pass into the tip of 

 the ascogonium. 



The further development is uncertain, 

 *='" '.\ iy^ ^ but apparently the nuclei pass to the base 

 of the ascogonium, while the tip dis- 

 organizes and disappears. Later, in the 

 position of the ascogonium, are seen 

 ^ binucleate cells, presumably derived from 

 the ascogonium, which form ascogenous 

 hyphae. The tips of these hyphae bend 

 over, a terminal cell is cut off, and 

 from the penultimate cell an ascus is 

 formed in which the ascospores develop 

 (Fig. 278). 



Each perithecium contains a number 

 of narrow, tubular asci which taper at 

 either end. Each ascus encloses eight 

 filiform ascospores. These ascospores 

 are liberated through a small opening 

 at the apex of the ascus. The asco- 

 spores can be carried by wind to the flowers of the rye, which, if they 

 are open, receive them. It has been recorded that the ascospores are them- 

 selves capable of budding off conidiospores which will also infect the ovaries 

 of rye plants. Thus the life-cycle is completed and we can represent it by the 

 following diagram (Fig. 279) : — 



?tr'\ihtt\um 



Fig. 278. — Claviceps purpurea. Peri- 

 thecium enlarged showing wall 

 enclosing asci and paraphyses. 



Sc/erotium 



Ascosp 



Claviceps ■ 

 Fig. 279. — Life-cycle of Claviceps purpurea. 



