388 BOTANY PART n 



not developed in Basidiomycetes, which are characterised by a special 

 kind of spore, the basidiospores. These are produced by a process of 

 budding on the characteristic BASIDIA, each of which bears a definite 

 number of spores, usually four. The typical basidia (Figs. 343, 344) 

 are either terminal tubular cells bearing the four spores at their 

 upper ends, or they are four-celled, each cell giving rise to a spore. 

 The spores are borne on thin stalk-like sterigmata, from which they 

 become separated when mature. The basidia agree with the asci in 

 containing when young two nuclei, which fuse with one another. The 

 resulting nucleus then divides into the nuclei for the four spores ( 7l ). 



In most Basidiomycetes the basidia are borne on or in special 

 fructifications, the origin of which is not, however, dependent on a 

 sexual process. 



The general name of CONIDIA is given to fungal spores which arise 

 by a process of budding, and the simple or branched hyphte bearing 

 them are termed conidiophores. The basidia are thus a special form 

 of the latter, but are distinguished from other conidiophores by their 

 peculiar nuclear fusion. 



Other forms of conidiophore in addition to the basidia occur in 

 the life-history of some Basidiomycetes. In the Ascomycetes also 

 the formation of conidia as well as asci is a widespread method of 

 asexual reproduction. In general, it may be said that the asexual 

 formation of spores in the Fungi takes place in a large number of 

 different ways. 



The direct origin of spores from the cells of a hypha which round 

 off, become thick-walled and ultimately separate from one another 

 (chlamydospores of Brefeld), must be distinguished from the forma- 

 tion of conidia. The spores of the Ustilagineae are thus formed in 

 rows, while the uredo-spoues of the Uredineae arise at the ends of 

 hyphae. 



All the asexual spores of the Eumycetes are provided with cell 

 walls, and are adapted for distribution through the air. 



Sub-Class I. Aseomyeetes (* . a* TO) 



The sexual organs have been accurately investigated in relatively 

 few forms ; a number of distinct types are found. 



1. In the Laboulbeniaceae (Fig. 342) the carpogonium with its 

 trichogyne, and the antheridia. which produce spermatia, show a 

 striking correspondence with the structures of the same name in 

 the Red Algae. 



2. The Ascomycetes which enter into the composition of Lichens 

 (Figs. 372, 373) approach most closely the preceding group. The 

 carpogonium is here a spirally wound filament of cells terminating in 

 a trichogyne. ' The spermatia are formed in special flask-shaped 

 depressions of the thallus, the spermogonia. Similar reproductive 



