388 BOTANY part ii 



through the substratum in all directions in their search for organic 

 nourishment. In many of the higher Fungi, however, the profusely 

 branching hyphae form compact masses of tissue. Where the fila- 

 ments in such cases are in intimate contact and divided into short 

 cells, an apparently parenchymatous tissue or PSEUDO-parenchyma 

 is produced. Such compact masses of hyphal tissue are formed by 

 some species of Fungi when their mycelia, in passing into a vegetative 

 resting stage, become converted into sclerotia, tuberous or strand- 

 like, firm, pseudo-parenchymatous bodies, which germinate under 

 certain conditions (Fig. 110). In the fructifications the hyjDhae are 

 also nearly always aggregated into a more or less compact tissue 

 (Fig. 109). 



The two sub-classes are distinguished by their respective 

 methods of asexual spore-formation. Tlie ASCUS is characteristic of all 

 Ascomycetes ; it is a club-shaped sporangium within which a definite 

 number of spores (usually 8) is formed in a peculiar Avay by free cell 

 formation (Fig. 317). The Basidiomycetes have in place of the 

 ascus a basidium of varying shape. It may either be four-celled or 

 a unicellular tubular structure from which the spores are abstricted by 

 a process of budding in definite numbers, usually four (Figs. 333, 334, 

 343). 



Sub-Class I.— Aseomyeetes (;'''' ^^' °^'' <'^) 



The Ascomycetes in their typical forms possess sexual organs, 

 the oogonia, which here go by the name of ascogonia or, as in the 

 Red Algae, of carpogonia, and antheridia. The sexual organs have 

 been accurately investigated in relatively few forms ; a number of 

 distinct types are found. 



1. In the Laboulbeniaceae (Fig. 332) 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. 360, 3G1) 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 sjjermogonia. Similar reproductive 

 organs occur in some Ascomycetes (e.g. Polystigma) which do not form 

 parts of Lichens. 



3. Pyrnnema Q'') (Fig. 326) and related genera, Ascodemiis 

 ( = Boudiera Claussen) ('-), Monascus ('*), AspergiUvs (™), exhibit a 

 distinct type. A multiinicleate carpogonium which is provided with 

 a trichogyne is fertilised by a multinucleate antheridium, the two 

 structures being thus coenogametes. Lachnea {'■''), the carpogonium 



