EU-MYCETES.-(a) ASCOMYCETES 



either case the result at ripeness is that the fruil appears as a dry 

 spherical sac, filled with ascospores set free by the disappearance ni 

 the ascus-walls, and of the nutritive tissues that embedded them. On 

 germination the ascospores form a new mycelium. (Fig. 367, 2, ; 4 



In Aspergillus both the antheridial and carpogonial cells are multinuclcAtr, 

 and it appears that sometimes a normal sexual fusion takes place. But in 

 others the antheridium degenerates, and sexual fusion is replaced by a fusion 

 of ascogonial nuclei in pairs. Thus Asper- 

 gillus illustrates that degradation of 

 sexuality, evidence of which is common 

 among the Fungi. 



The type of life-history seen in these 

 simple Mildews and Moulds is common 

 for other Ascomycetes, though it may be 

 worked out with greater complication. 

 But in many of them the sexual organs 

 are so degraded that they, or their 



A />• 



Fig. 368. 

 A, a sclerotium of Peziza, which has germinated and given rise to uuiiirrou» 

 trumpet-shaped discs. B, section through such a sclerotium (sr), and the /Vxim 

 disc (rf) to which it has given rise. 6=stalk. a = asci. Magniliofl and bliRhtly dia 

 grammatic. (From Marshall Ward.) 



equivalents, if present, have hitherto escaped observation. There is normally 

 an alternation of generations, the critical points of which are the scxu.il 

 fusion in the carpogonium, and the rediiction which precedes the fonnatio!-. 

 of the ascospores. The stage of the ascogenous hyphae, which intervcnt-^ 

 l)etween these events may be regarded as a diploid sporophyte. The rest ^^ 

 held to be the haploid gametophyte, which is Uable to indefinite repoiiti' 

 means of conidia. The fruit-body is then a composite struct urtr. coiv 

 essentially of the ascogenous hyphae. constituting the sporophyte. \\\ 

 enveloped in a covering derived from the mycelial gametophyte. I he w 

 analogies are with the fruiting bodies of the Red Seaweeds. 



Both the mycelial and the fruiting stages of Ascomycctous 1 

 are subject to modifications according to habit and circumst. 

 and either may attain large size. The mycelium may, by repeated 



