10 UREDOSPORES 
four) germ-pores; in fact, the uredo- resembles the ecidiospore 
in character, and must be considered as homologous with it— 
the stalk-cell corresponding to the intercalary cell of the latter. 
But they differ considerably in the fact that the uredospore is 
always produced singly, not in chains. 
(This is not true, however, of all 
the Uredinales.) The membrane of 
the uredospore is nearly colourless, but 
it encloses a bright orange granular 
and oily mass, with two nuclei. Every 
cluster of uredospores produced on the 
same spore-bed is called a sorus; it is 
surrounded by the laciniz of the epi- 
dermis, which is more or less torn or 
Fig. 10. Leaf of Carex split by the enlarging mass. In many 
pendula, with uredo- and . 
teleuto-sori, slightly en- C488, several sori become confluent 
larged. and form a larger pustule (Fig. 10). 
In other species of Uredinales the uredospores have coloured 
membranes or possess a larger or smaller number of germ- 
pores. Moreover the distribution of these pores over the 
surface is characteristic for each species: they may be placed 
equatorially, as they are in P. Caricis (Fig. 11), or towards 
the poles, or scattered over the surface with regularity or 
without any order. 
A uredospore may be very easily detached from its pedicel, 
and a ie (chiefly by wind, though sometimes by insects) 
ype to another leaf of Carew, on which it 
germinates, the germ-tube enters a stoma, 
produces a fresh crop of mycelium and 
another sorus of uredospores; this process 
can be repeated indefinitely. The my- 
celium can also grow up and down the 
Be map Hee leaf, producing fresh sori in its course ; 
showing the three for this reason the sori are usually 
germ-pores. x 600. arranged in linear series, owing to the 
parallel venation of the Carex-leaf. The germ-tubes of the 
uredospores are often curled or branched like those of the 
secidiospores, and the germination is of the same character in 
