76 PHYLOGENY 
on the higher families would be expected to show the greatest 
advance. This consideration alone is sufficient to determine 
that Uredinopsis is like one of the primitive Uredinales and 
that the genera Puccinia and Uromyces contain the highest 
types. For Uredinopsis grows upon Ferns, and more than a 
quarter of the Pucciniae live on the Composite. 
Secondly a comparison of the spores of these two genera 
and their respective allies suggests that the possession of a 
single definite and well-formed germ-pore is a characteristic of 
the latest forms, while the primitive ones had no germ-pores 
at all, but protruded the germ-tube, as a conidium usually 
does, at any convenient point or where the wall first gives way. 
There is reason, from another point of view, to conclude that 
germ-pores, when first existing, were numerous and indefinitely 
scattered. A gradual reduction in their number and their 
restriction to definite parts of the spore-wall occurred during 
the course of evolution. The ecidio-teleutospore of Hndo- 
phylam has no germ-pore; in the Pucciniacee the ecidio- 
spores have usually several indistinct ones, the uredospores 
have them fewer and more easily visible, and the teleutospores 
have one or a small number, oftentimes very plainly marked. 
Amongst the other Fungi, the group which presents the 
nearest approach to the Uredinales is that of the Ustilaginales, 
which are also parasites; their teleutospores (brandspores), in 
the family Ustilaginacez, germinate in a similar way, but with 
less definiteness, by the formation of a basidium and basidio- 
spores. It may be inferred that this particular feature is one 
of the most deeply seated characters of both groups, and is 
therefore inherited from their ancestors. 
Moreover, this feature is exhibited in the Uredinales by 
cells which belong to the sporophytic generation, and after a 
certain amount of growth the mycelium produced by the 
basidiospores bears the two kinds of gametes. An exactly 
similar course of events takes place in certain Algae, e.g. 
Grifithsia, where the sporophyte bears tetraspores which on 
germination produce a thallus which bears gametes. It is true 
that in the Red Alge the tetraspores are more usually arranged 
in tetrahedral fashion, but other modes also obtain, among them 
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