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1894.) The Homologies of the Uredineae. 991 
the wheat. In many heteroecismal species it has hitherto been 
found impossible to determine the aecidium belonging to it, 
and for many aecidia occurring upon common plants, the 
uredo and teleutospore stages are not known. The difficulties 
surrounding this problem are so great as to discourage the 
attempt to solve them. 
Howorocv or PARTS. 
Having now a general idea of the structure of the Uredineae, 
we come to the important question of the homology of their 
parts. Here, again, we are beset with difficulties, No sexual 
organs have yet been discovered, and there has been very much 
structural degeneration of the whole plant. 
In their general structure the Uredineae show clearly that 
their relationship is with the Ascomyceteae or Basidiomyceteae 
rather than with the Phycomyceteae, and upon this point there 
has been little disagreement among recent botanists. Some 
authors regard the aecidium as a kind of degenerated apothe- 
cium, in which each conidial chain is a modified ascus. In 
this view, the aecidium is the result of an obsolete or obsoles- 
cent sexual aet, as in the Discomyceteae, and the uredospores 
and teleutospores are considered to be conidial structures. 
Accordingly, those who hold this view quite consistently set 
off the Uredineae in a class bearing the name Aecidiomycetes. 
By far the greater number of botanists, however, now regard 
the teleutospores as basidia, homologous with the basidia of 
the Hymenomyceteae and Gasteromyceteae, and they therefore 
place the Uredineae in the class Basidiomyceteae. In this view, 
the sporidia which develop upon the germination of the teleu- 
tospore are basidiospores, homologous with those of mushrooms 
and puff balls, and the uredospores and aecidiospores are forms 
of conidia. It is needless in this paper to set forth these views 
at length, since they may be found in almost any common 
text-book of botany. 
Briefly stated, the view which I wish to present 1s that the 
" teleutospore," so-called, is a tightly fitting aseus, containing 
one or more large spores; the teleutosorus is à reduced apo- 
thecium ; the aecidiospores are the normal conidia; and the 
