Presidential Address. F. T. Brooks. 25 



is considered in detail, although the difterences between basidio- 

 spore and ascospore formation are considerable, these are not 

 so profound as might be thought at first sight. The divergence 

 in method of spore formation and spore discharge between the 

 Ascomycetes and the Basidiomycetes is correlated with diversi- 

 ties in style of architecture, but in both groups the spore mother 

 cells are fundamentally the same and are often miiltipUed in- 

 definitely to pro\'ide for an enormous spore output. 



The Uredineae and Ustilagineae are pecifiiar groups of 

 obhgate or semi-obhgate parasites which show no close relation- 

 ship with other Basidiomycetes, but which undoubtedly fall 

 within this category. The Uredineae in particular exhibit con- 

 siderable resemblance to the Ascomycetes. No one who has 

 worked on the c\-tolog},' of such forms as Gnomania, Polystigma, 

 or the hchen fungi can fail to be impressed by their hkeness in 

 certain respects to rust fungi. The spermogonia of both and 

 certain features in the development of aecidia and perithecia 

 show a marked resemblance, which may point to ancestr\" from 

 a common stock or may be of even greater phylogenetic sig- 

 nificance. The similarity between certain Ascomycetes and the 

 rust fimgi was commented upon by de Bar\'* many years ago, 

 and I ventured to call attention to it in a paper on Gnomonia 

 erythrostoma pubhshed in igiot. The gap between the Basidio- 

 mycetes and the Ascomycetes is not unbridgeable, and a com- 

 mon origin for both groups is indicated. The divergence between 

 them is of long standing, and may date back to the time when 

 they, together with early forms of the Phycomycetes, began 

 to be evolved from the first organisms of a definitely fungoid 

 nature. It mav be mentioned here in passing that there is 

 much to be said for separating the Smut and the Rust Fungi 

 from all other basidia-producing fungi, and constituting them 

 a group of equal rank with the Ascomycetes and the remainder 

 of the Basidiomycetes. 



It is maintained, therefore, that the fungi are a monophyletic 

 group, estabhshed in far-distant times from protist organisms, 

 which have evolved along their own fines just hke any other 

 large group of plants or animals. In the past a poh-phyletic 

 origin for many groups of organisms including fungi has been 

 advanced, but the present trend of opinion is in favour of 

 attributing each phylum to a common ancestry, notwithstanding 

 the existence of great discontinuity of t^-pe within the phylum. 

 It is admitted that it is particularly difficult to trace relation- 



* de Ban,-, A. , Comparative morphology- and biology of the fnngi, mycetozoa 

 and bacteria. English translation (1887). 



t Brooks, F. T., The Development oiGnomonia erythrostoma Pers. Ann. Bet. 

 XXIV, p. 585 (1910). 



