THE SEXUALITY OP THE FUNGI. 31 



There is little need to dwell on this scheme, since its chief interest 

 for us is in its being an intelligible attempt to classify the fungi from 

 the point of view of the theory of descent. A point of some impor- 

 tance, however, may be referred to, as we shall have occasion to speak 

 of it later. Brefeld indicates the possibility that the Oosporece (typi- 

 fied by Peronosporece) may be allied to the " true fungi " otherwise 

 than by a common descent from some Alga-like ancestor. He also 

 recognises a common origin for the Oosporece and the Zygomycetes. In 

 other respects the system is chiefly remarkable for the peculiar views 

 taken of the descent of the two great groups, the typical Basicliomycetes 

 (Gasteromycetes and Eymenomycetes, &c.) and the Ascomycetes, which 

 he regards as having long ago diverged from a common point, at a 

 time when the ancestral forms commenced to specialise their repro- 

 ductive organs. While on the one hand asci arose as specialised forms 

 of sporangia — complications resulting from the development of peri- 

 thecia, &o, being considered unimportant — on the other hand, the 

 sporangia became degi'aded to conidia, and the Basicliomycetes came to 

 be merely highly developed tufts of conidiophores. 



Tn a later memoir l Brefeld insists on regarding the so-called Polli- 

 noclia of the Ascomycetes as simply tubes for enveloping the ascogenous 

 cell or filament ; and it is interesting to note that he quotes Melano- 

 spora as a case where the non-sexual relation of the ascogenous cell 

 and the filaments which envelop it may be clearly observed. Brefeld 

 also points out that in the Ascomycetes we can trace gradual degra- 

 dations of the various forms of fructification, with a disappearance of 

 sexuality at the same time. He supposes that all the fungi arose 

 from an ancestral form containing chlorophyll and possessing sporangia, 

 and that the variations met with are derived by modifications of this 

 sporangium, as already indicated. 



It seems unnecessary to criticise these views in detail, since it is 

 obvious that no decision can be arrived at apart from the considera- 

 tion of numerous facts. It will be noticed, however, that Brefeld's 

 hypothesis assumes that, in addition to purely vegetative modes of 

 multiplication (e. g. the breaking up of filaments, &c), certain fungi 

 must have acquired other forms of reproduction than those inherited 

 and specialised— some uEcidiomycetes, for instance, with their four 

 kinds of spores or spore-like bodies (eecidospores, spermatia, uredos- 

 pores, and teleutospores) must have acquired at least one of these spores. 



1 * Schiramelpilze/ iv, 1881. 



