16 ARTHUR: PROBLEMS IN THE StTuDY OF PLANT RusTs 
guises, and if they were sufficiently on the alert they probably 
would not be. Yet it is not rare to have new species of rusts 
described because the describer did not recognize the host under 
its latest name, as an old-time acquaintance. This failure of recog- 
nition also leads to a fictitious multiplication of hosts cited for a 
species of rust. Saccardo’s ‘‘Sylloge Fungorum”’ contains many 
instances of this. I may, however, mention a specific instance 
taken from a later work, in which greater accuracy is expected, 
that of Sydow’s “ Monograph of the Uredineae.’’ The second part 
of this work, just from the press, gives /erau/a dissoluta and Lepto- 
taenta dissecta as two hosts for a species of Puccinia, and yet both 
are names of the same plant. This is not a solitary instance. 
Such discrepancies ought not to occur, and largely would not if 
more importance were attached to the identity of the host. 
There are many topics connected with this intricate and many- 
sided subject of the rusts that I should like to bring before you at 
this time, but to do so must prove wearisome, even to enthusiastic 
students of the family ; and I fancy there are a few such in this 
audience. I will, therefore, content myself with a single additional 
topic, and even that must be treated briefly. 
I wish to point out the profound influence that cytological 
studies are likely to exert upon the morphological, evolutionary 
and taxonomic conceptions of the rusts, when these are carried 
far enough to explain the significance of nuclear fusions in the 
different sorts of spores, and to indicate where in the life-cycle the 
sexual fusion occurs, or originally did occur. Much patient work 
has already been done by eminent investigators, Dangeard, Sappin- 
Trouffy, Raciborski, Poirault, Harper and others, and many facts 
have been brought to light, but we are more bewildered than edi- 
fied by the results. 
There seem to be a few things that we may accept as reason- 
ably certain. One is that no close relationship exists between the 
Uredineae and the Ascomycetes, as advocated by DeBary, but that, 
on the other hand, the Uredineae and the Basidiomycetes have 
direct kinship. The nuclear fusions found in the teleutospore and 
in the basidium appear to be of similar nature, although probably 
without sexual significance. 
The simple structure of the vegetative parts of the Uredineae 
si be icls Aaa iaal 
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