a British Uvredinee and Ustilaginee. 
for. The vegetative mycelium of most of the Uredinez 
is very similar, although the spores are very diverse. The 
mycelium, being present in the appropriate host-plant, may 
give origin to several different kinds of spores, according 
to the nature of the Uredine under examination, each kind 
of which was regarded by the older botanists as being a 
distinct genus (cidium, Uredo). While it is true that 
the relationship between the various spore-forms was 
suspected as early as the beginning of the present century, 
yet its actual demonstration has been accomplished only 
within the last thirty years. From the investigations of 
Tulasne and De Bary, we now know that each spore-form 
has a life-history of its own, that they are often products 
of the same mycelium grown among different environments, 
and that they all arise from some antecedent spore-form. 
The ultimate condition in which all the Uredinez are 
encountered is the teleutospore, which, after a longer or 
shorter period of quiescence, manifests its vitality by ger- 
minating and producing a body—the promycelial spore. 
The promycelial spore may then be regarded as the 
beginning of the series of spore-forms of which the teleu- 
tospore is the end. 
The actual number of spore-forms intervening between 
the promycelial spore and the teleutospore is subject to 
considerable variation in different species, 
1. The promycelial spore, after emitting a germ-tube, 
which enters the tissues of its appropriate host-plant, may 
give rise to a mycelium, which produces teleutospores 
exactly similar to the teleutospore from which it originated 
(Leptopuccinia, Micropuccinia). 
2. The promycelial spore in a second group of the 
Uredinez, in like manner, gives rise to a mycelium which 
produces uredospores, and subsequently teleutospores 
(Hemipuccinia). 
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