188 TEXT-BOOK OF FUNGI 



therefore either represents a third independent departure 

 from the Florideae, or a spontaneous evolution of a 

 trichogyne. 



^ It has already been stated that even in the Phycomy- 

 cetes the original sexual phase showed a decline, and that 

 in certain species it had completely disappeared, leaving 

 the asexual conidial stage as the only representative of the 

 species. This condition of things is much more empha- 

 sised in the Ascomycetes, where from the present stand- 

 point of knowledge the great majority of species are asexual, 

 in the sense of the sexual organs, when present, being no 

 longer possessed of functional activity, whereas in numerous 

 species the sexual organs are more or less rudimentary, or 

 have entirely disappeared, and the structure producing 

 spores that were originally of sexual origin remains in 

 other respects unchanged. 



It may perhaps be advisable to state that, taking the 

 entire group of fungi into consideration, not more than a 

 score of species are known to produce fruit as the result 

 of a sexual act, that is, due to the fusion of a male and a 

 female nucleus. All the rest is assumption or founded on 

 analogy. 



On arriving at the Basidiomycetes it is found that all 

 trace of a sexual generation has completely disappeared, 

 and the species as such consist of the conidiophore stage 

 alone. This being the case the phylogenetic affinity of the 

 Basidiomycetes cannot be determined from cytological 

 evidence afforded by the sexual organs. 



My idea of the evolution of the fungi is as follows, 

 based on morphological evidence. 



The Oomycetes section of the Phycomycetes are the 

 most primitive of fungi at present known, and descended 



