80 PHYLOGENY 
spermogones. The first stage of evolution was the separation 
of this spore-form into two, one (the ecidiospore) germinating 
conidially, the other (the teleutospore) following it and germi- 
nating basidially: types approximating to this stage are seen 
in the section Pucciniopsis. It is quite certain that uredospores 
are only modified xcidiospores, formed as a mere multiplying 
device without the intervention of another fusion-cell. The 
peridium which is found in these later stages of evolution round 
the ecidium was at first represented (doubtless even in the 
primitive Endophyllum) by a mere circle of paraphyses or 
not.at all. 
From a cytological point of view, the fusion of the two 
nuclei in the teleutospore may be taken as paralleled by the 
similar fusion in the basidium of the Basidiomycetes; the 
division into four basidiospores follows in both cases, although 
the mechanism is different. If the view propounded in a 
previous chapter is adopted, that the four cells of the “basidium” 
of the Uredinales are the real tetraspores' and the basidiospores 
are merely conidia whose function is to facilitate dispersion by 
wind, it will be seen that the difference in the Basidiomycetes 
consists in the fact that cell-walls are not formed round the 
tetraspores previously to the production of conidia. This may 
recall the fact that in the Red Algee the four spores in a tetra- 
sporangium are also not surrounded by cell-walls before their 
discharge into the water. Of course, in the subaérial Uredinales 
and Basidiomycetes such naked masses of protoplasm would be 
comparatively ineffective for propagation, and are here replaced 
by methods more suitable to a land environment. The throw- 
ing off of the basidiospores with a jerk appears to be the same 
in both these groups. 
A similar comparison with the Ascomycetes cannot be made 
with equal advantage, until the students of that group of Fungi 
have come to some semblance of agreement as to the actual 
course of its cytological history. But it is impossible to over- 
look the remarkable parallelism between the cytology of the 
1 In the Himalayan Barclayella, which is placed among the Melampsor- 
aces (?), these tetraspores are said to round themselves off and separate, 
apparently as the normal mode, without forming basidiospores. 
