Generations , and General Cytology of the Uredmeae. 343 
The nuclei of the free uredospore have sometimes a peculiar, irregular 
contour as seen in Fig. 84 ; this appears to be only a temporary phase 
of development. 
DEVELOPMENT OF TELEUTOSPORES. 
Phragmidium violaceum. 
The teleutospores appear on the leaves towards autumn, and are 
at first mixed with the uredospores, but later arises in sori which consist 
of teleutospores only, surrounded by a layer of paraphyses. The mycelium 
on the leaf from which they arise shows a septate mycelium with a pair 
of nuclei in each cell. In Fig. 85 the paired nuclei can be distinctly seen 
in the haustoria in the cells marked * and in several of the other cells, 
but owing to the thinness of the section the nuclei appear single in 
a number of cases. 
From this mycelium there grow up, when the teleutospore sorus is to be 
developed, a number of rectangular, binucleate basal cells closely packed 
beneath the epidermis. It is from these special cells (which Sapin-Trouffy 
has figured in a diagrammatic way) that the teleutospores are developed. 
The young teleutospore appears first as an elongated, binucleate, cylindrical 
outgrowth from the basal cell. It increases in diameter, and soon cuts off 
from the apex downwards a series of three or four superposed cells (Figs. 
86, 86 a ), which form the body of the teleutospore, the lowest cell becoming 
the stalk. The upper cells take on the characteristic shape, and the walls 
become thickened. The upper cell grows out into a short, narrow projection 
(Fig. 86 b ), the cavity of which soon becomes completely or almost com- 
pletely obliterated by the great increase in thickness of its wall ; there is 
thus produced the knob-like projection characteristic of the mature spore. 
The lowest cell, the stalk, increases very greatly in length, and its 
cavity becomes almost completely obliterated by the thickening of its 
walls, except in the lowest part where it is inserted on the basal cell. Here 
there is a cavity of considerable size in which the two disorganized nuclei 
are to be found (Fig. 86 c). Some evidence was obtained of a pit connecting 
for some time the end of the stalk with the basal cell (as in the case of the 
uredospore and its stalk) ; the absence of thickening at this point, and the 
peculiar widening of the cavity shown in Fig. 86 c, strongly suggest such 
a connexion, though its existence was not established with certainty. 
During the process of thickening of the wall of the spore the 
nuclei in the cells show each a single well-marked nucleolus and granular 
chromatin, and are usually to be found close together (Figs. 86, 86#). 
When the wall is fully thickened the process of nuclear fusion begins. In 
the first stage the two nuclei are found in close contact (Fig. 87 a) ; in the 
second stage instead of two small nuclei one larger one is found, but the two 
