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derived
EUSTS. 99
minute^ cellular^ linear bodies called spermatia^ invested
with a kind of mucous substance^ that overflows
with them from the orifice of the spermogone^
like lava from the crater of a miniature volcano.
The rust in company with which they have been
found most plentifully,
is that which covers the
under surface of the leaves of the commonest of
The external form of
all thistles {Cnicus arvensis).
one of these spermogones is figured plate VII.
fig. 153. The rust possesses, when fresh, a peculiar
odour, which is said to resemble that of orangeflowers
;
•
whence was its name of ^^ sweetsmelling
rust^^ (Trichohasis suaveolens, Lev.). M.
Tulasne writes :—^'
With respect to this species, it
is, in my opinion, but the first form of a Fiiccinia,
analogous to P. Comjpositarum, D.C. the spermogones
with which it is mixed being very abundant,
:
it
ought to be placed with that Puccinia. I should,
perhaps, retain some doubts upon the legitimacy
of this relationship,
if it had not been my fortune
to meet on another species of the same kind {Puccinia
AnemoneSj P.) spermogones perfectly characterized,
and in which the colour, habit, and position
would not allow me to hesitate an instant in attributing
them to the Puccinia.^' In this species of
rust the whole under surface of the leaf is covered
with a purphsh-brown dusty coating of the spores,
from the numerous pustules which are produced
(plate VII. fig. 151). The plants, when attacked,
have a paler and more sickly appearance ;
the leaves
A 2