270 



STRUCTURE AND LIFE HISTORIES 



(Fig. 185). The cells from this point on, to and including 

 the formation of the ascus, are diploid, and therefore 

 constitute the sporophytic generation. 





Fig. 195. — Lilac mildew {Microsphcera Alni). A, perithecium, with 

 appendages; B, perithecium, showing asci (a); C, an ascus, containing 

 ascospores; D, conidiophore (cph), bearing a chain of conidia (conidio- 

 spores, c.s); E, beginning of fertilization; antli, antheridium; car, carpo- 

 gonium; F, later stage in fertilization; the contents of the antheridium and 

 carpogonium have fused; /, fusion of the two nuclei; G, germination of 

 ascospore (a.s); g.t, germ tube. (£ and F after R. A. Harper.) 



262. Germination. — Reduction occurs during the forma- 

 tion of the ascospores. When an ascospore germinates it 

 develops directly into a mycelium. 



263. Life-cycle. — The Hfe-cycle of Microsphcera may 

 be tabulated as follows: 



