COMPARISON WITH 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 hyphz 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 Auriculariez, 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- 
sportum 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. 
Nore. Werth und Ludwigs (1912) showed that the teleutospores of Puccinia 
Malvacearum arise by the conjugation of two basal cells like those of an ecidium, 
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. 
