622 



LECTURE XXII. 



dium with those of the trichogyne takes place. The effect of 

 this fusion is soon manifested in the dilated basal portion, 

 ascogonium, of the female organ. It increases in size and 

 developes short tubular outgrowths, the ascogenons hypJice, 

 which give rise to numerous asci in which ascospores are 

 eventually produced. Whilst this is going on, the female 

 organ and its ascogenous hyphae become surrounded by a 

 dense upgrowth from the mycelium, the whole forming the 

 characteristic fructification (apothecium). 



Fig. 73 (after Stahl). A section of the thallus of a Lichen (Collcma micro- 

 phyllum\ shewing the ascogonium us and the projecting end of the trichogyne tr. 

 B end of trichogyne surrounded by spermatia. C fusion of a spermatium with the 

 terminal cell of the trichogyne. 



But besides these sexual Ascomycetes in which there is no 

 differentiation of sexual reproductive cells, there are others in 

 which male reproductive cells are differentiated, though in no 

 Ascomycete is there any differentiation of female reproductive 

 cells. The differentiation of male reproductive cells takes 

 place in certain Ascomycetes in which, unlike Eremascus and 



