STRUCTURE. 37 
cellular passages, and may sometimes be found in parts of the 
plants where the fungus does not develop itself. There is no 
proper excipulum or peridium, and the spores spring direct 
from a more compacted portion of the mycelium, or from a 
cushion-like stroma of small cells. In 
Lecythea, the sub-globose spores are it 
first generated at the tips of short 
pedicels, from which they are ulti- 
mately separated; surrounding these 
spores arise a series of barren cells, yy ; 
_ i wW a We 
or cysts, which are considerably larger py, 1¢ —Barven Cysts and Pseudo- 
than the true spores, and colourless, Spores: Ob Levy lets 
while the spores are of some shade of yellow or orange.* In 
Trichobasis, the spores are of a similar character, sub-globose, 
and at first pedicellate; but there are no surrounding cysts, and 
the colour is more usually brown, al- 
though sometimes yellow. In Uredo, 
the spores are at first generated singly, 
within a mother cell; they are globose, 
and either yellow or brown, without 
any pedicel. In Coleosporium, there 
are two kinds of spores, those of a 
pulverulent nature, globose, which are 
sometimes produced alone at the com- 
mencement of the season, and others Fic. 17.—Coleosportum Tussilaginis, 
which originate as an elongated cell ; ney 
this becomes septate, and ultimately separates at the joints. 
During the greater part of the year, both kinds of spores are to 
be found in the same pustule. In 
Melampsora, the winter spores are 
elongated and wedge-shaped, com- 
pacted together closely, and are only 
matured during winter on dead leaves ; 
the summer spores are pulverulent 
and globose, being, in fact, what were until recently regarded 
Cia = 
Fic. 18.—Melampsora salicina. 
* Léveillé, ‘‘Sur la Disposition Méthodique des Urédinées,” in ‘‘ Ann. des 
Sci. Nat.” (1847), vol. viii. p. 369. 
