304 PART IV. CLASSIFICATION. 



In the higher Basidiomycetes (Autobasidiomycetes) the basidia 

 are unicellular, but in the lower forms (Protobasidiomycetes) they 

 are multicellular, either with transverse septa (Pilacrese, Auricu- 

 lariese), or with longitudinal septa (Tremellinese, Fig. 184). 



The number of spores borne by a unicellular basidium is usually 

 four ; but it may be one (species of Hymenogaster), or two (Calo- 

 cera, Dacryomyces, species of Octaviana and Hymenogaster), or 

 4-8 (Phalloidese). In the case of the multicellular basidium, each 

 cell bears one basidiospore. 



Simple conidiophores have been discovered in several forms (e.g. 

 Pilacre Petersii, Auricularia sambucina, Exidia, Trcmella 

 mesenterica and lutcscens. In these forms the basidiospore gives 

 rise, on germination, to a mycelium, sometimes small and un- 

 branched, which is either itself the simple conidiophore, or bears 

 simple conidiophores, on which conidia are formed by abstriction. 

 The same mycelium may subsequently bear the compound sporo- 

 phores ; or the conidia-bearing form may reproduce itself through 

 successive generations until at length, under appropriate con- 

 ditions, the form bearing the compound sporophores occurs. 



The conidia of Tremella, cultivated in nutrient solution, mul- 

 tiply rapidly by budding, producing yeast-like cells which have 

 not, however, the power of exciting alcoholic fermentation. 



The formation of unicellular gemmae (see p. 277) is of common 

 occurrence in the Basidiomycetes ; either in the form of chlamydo- 

 spores (e.g. Nyctalis, Oligoporus, Fistulina) ; or, more commonly 

 (e.g. species of Coprinus, Clavariese, Polyporus, Cyathus, etc.) in 

 the form of oidium-cells. The chlamydospores are especially de- 

 veloped in the basidial fructifications of the plants in which they 

 occur : the oidium-cells are generally developed from the vegeta- 

 tive mycelium, either the whole of it or individual hyphse, forming 

 sometimes a more or less definite fructification. In some Agaricinse 

 (e.g. Coprinus, Clavariese) the oidium-cells appear to be incapable 

 of germinating. 



Sclerotia (see p. 277) are known in some cases. The mycelium 

 (e.g. species of Typhula, Coprinus stercorariuSj Tulostoma) pro- 

 duces sclerotia as an antecedent to the formation of the compound 

 sporophores; the sclerotia become quite free from the mycelium, 

 and may be kept for months without losing their vitality. On 

 germination each sclerotium gives rise to one or more compound 

 sporophores. The most remai'kable sclerotia are those of Agaricus 

 mclleus, a Fungus which is very destructive to timber. The 



