i 9 2 TEXT-BOOK OF FUNGI 



Finally, as to Dangeard's idea respecting sexuality as 

 to whether it falls within the preconceived idea as to what 

 actually constitutes a sexual act or not I am not in the 

 least concerned; to my mind the fusion of nuclei, as 

 described by Dangeard, answers the purpose of a sexual 

 act inasmuch as it imparts vigour or rejuvenescence. I 

 fail to see that its efficacy is negatived by the fact that it 

 occurs in some species where the older or acknowledged 

 sexual method is yet present. It appears to simply signify 

 that the newer (Dangeard's) method of rejuvenescence 

 evolved before the older truly sexual method was com- 

 pletely obliterated, hence the two types overlapped. It is 

 a parallel case to the coexistence of sexual and conidial 

 forms ; the original sexual type was destined to go, and 

 the conidial state to take its place, and to give us the most 

 highly organised and perfect forms, the Basidiomycetes. 

 But the new or conidial type appeared long before the 

 sexual stage disappeared, in fact the two stages overlapped 

 to the end of the Ascomycetes. It is only the newest 

 group, the Basidiomycetes, that is absolutely free from 

 vestiges of the primitive sexual stage. 



There yet remains to be noticed the enormous assem- 

 blage of forms usually included under ' Fungi imperfecti,' 

 otherwise known as Hyphomycetes, Sphaeropsideae, etc. 

 In many systems these groups are entirely ignored, pre- 

 sumably on the supposition that they are simply conidial 

 forms of higher fungi. In purely systematic works these 

 groups are included and treated, so far as descriptions are 

 concerned, as entities or species. 



Many of these species are probably only conidial forms 

 or phases of ascigerous fungi; but there remain many 

 hundreds that have not been proved by pure cultures, or 



