12 TELEUTOSPORES 
is much thicker at the apex than elsewhere (Fig. 13). While 
the spores are standing in a densely crowded 
\ sorus, the apex is the part most exposed to the 
: weather, and therefore most needing protection. 
There is a thin endospore to each cell: the 
contents are granular and at first oily; there 1s 
a large and conspicuous nucleus in the centre 
of each. This nucleus, in its resting stage, 1s 
almost homogeneous except for its nucleolus, 
and was mistaken by the older observers for 
a “vacuole.” 
Since the mycelium from which the teleuto- 
Fig.13. Teleuto- Spores, as well as the uredospores, were formed 
spore of P. gontains paired nuclei, the cells of the teleuto- 
Caricis. x 600. " . Lee 
spore were at first in the same condition. When 
its wall, however, begins to thicken, ie. when it is becoming 
mature, the conjugate nuclei unite, and form one large fusion- 
nucleus (Fig. 14). The two fusing nuclei, after the very 
@ 
& o ae 
© 
4* 2 
a b c d e 
Fig. 14. Formation of teleutospores of P. Falcariae (after Dittschlag) ; 
u, the spore-bearing hypha; b, the same divided into pedicel and 
spore-cell; c, the spore divided into two cells; d, a young teleuto- 
spore; ¢, the same after the fusion of the nuclei. x about 800. 
numerous conjugate divisions during the long period of growth 
from the formation of the fusion-cell of the secidium, would be 
related, as it were, like very distant cousins, especially since 
the nuclear divisions during this period, though indirect, appear 
to show a very simplified form of mitosis, tending rather to be 
of the nature of amitosis. The fusion, as already intimated, is 
not to be considered as the act of fertilisation, but merely as a 
necessary preliminary to chromatin-reduction. 
