COMPARISON AV1TH BASIDIOMYCETES 29 



which takes place in the maturing teleutospore, occurs also in 

 the basidium of the Agaricini and Polyporei, followed by a 

 division of the fusion-nucleus into four nuclei of which one 

 passes into each basidiospore, although it is not yet ascertained 

 how or where the cells of the hyphse of those Fungi become 

 binucleate. From this point of view it is evident that the 

 chief difference between the basidiospore-formation in the 

 Basidiomycetes and in the Uredinales lies in the fact that, 

 in the former, the four tetraspore-nuclei are not surrounded 

 by cell-walls previously to the production of conidia, as they 

 are in the latter. 



The basidium of some of the Hemibasidiomycetes, e.g. of 

 the Auriculariese, is divided into a row of four super-imposed 

 cells of an exactly similar character to that of Puccinia, each 

 cell also giving rise to a basidiospore on a sterigma in the 

 same way. The similarity of this basidium to that of Coleo- 

 sporium is not diminished by the fact that it also is surrounded 

 by a gelatinous mass through which the sterigmata protrude. 

 Had not this primitive mode of forming the conidia been 

 modified into that typical of the Agaricini, there would have 

 been no opportunity for those wonderful and intricate contri- 

 vances for facilitating spore-dispersal which Buller has pointed 

 out (1909) and which find their highest and latest development 

 in Coprinus. 



The Uredinales must be considered a highly organised 

 group of comparatively recent evolution, as is evident also from 

 their exceedingly complex parasitism. They are not a stage in 

 the evolution of the ordinary Basidiomycetes, but the end-group 

 of a different branch. 



Note. Werth und Ludwigs (1912) showed that the teleutospores of Puccinia 

 Malvacearum arise by the conjugation of two basal cells like those of an secidium, 

 but usually of unequal size. The nucleus of the smaller cell passes into the 

 larger; the fertilised cell then forms, by conjugate division, a short chain of 

 binucleate cells, of which the two upper become the teleutospore. 



