RUSTS. 
319 
again in distinct cysts, resembling very closely similar bodies 
in lichens ; and we have a third kind of cysts, containing the 
usual sporidia in sausage-shaped hyaline sacs ( asci ). Even 
here, however, we have not done with marvels ; for if the 
sty losp ores are placed in water, they produce in the course of 
twenty-four hours conidia of a second order, exactly analogous 
to those which arise on the germination of the spores of the 
rusts and mildews which affect our cereals and other plants. 
Further reference is also made to three species of moulds, 
which M. Tulasne has shown to be only varied forms of the 
mycelium of a species of SjAiceria common to various plants ; 
these moulds having been hitherto regarded as fungi perfect 
in themselves. 
It is unnecessary to adduce other instances to prove 
that di-morpliism is far from uncommon. In the Uredines, 
to which this paper is devoted, the genera known as 
Lecythea and Tricliobasis are by some mycologists excluded 
altogether, as containing only species which are mere forms 
of more highly developed uredines, such as Piiccinia, Aregmci , 
and others. On the other hand, they are retained by those 
who possess a lingering doubt whether both forms may not be 
distinct, though developed from the same pustule. As the 
two forms are distinct in appearance, it will better answer my 
present purpose to treat them separately, notwithstanding my 
belief that, in a scientific point of view, the evidence is all in 
favour of their union. 
Unfortunately, the first group of fungi to which I wish 
to direct our readers* attention, contains species but too well 
known for their ravages amongst graminaceous plants, 
especially the cereals. Rust/* as it is generally called, has 
a reputation little better than mildew, and it really deserves 
no better, for it is only another form of that pest of the farm, 
from the mycelium of which the corn-mildew is at length 
developed. There are two species very closely allied (doubtless 
only forms of the same species with different spores) which 
attack the leaves and culms of growing corn, and, bursting 
through the cuticle in the manner represented in Plate XII. 
fig. 9 (magnified), give a peculiar rusty appearance to the 
plant, as represented in fig. 8. One of these corn-rusts is 
botanically named Tricliobasis rubigo-verci , Lev., or the true 
rust Tricliobasis ;** the latter, which is the generic name, being 
a compound of two Greek words ( thrix , a hair, and basis, a 
foundation), on account of the spores being at first furnished 
at their base with a short thread-like peduncle, which at 
length falls away (Plate XII. fig. 10). The other corn -rust 
is Tricliobasis linearis, or “line-like Tricliobasis,’’ because the 
sori or pustules are linear, or lengthened out like a line ; the 
