and Life-history of Puccinia Graminis . 219 
that the granular protoplasm of the spore becomes vacuolated, 
and the contents pass into the germ-tube. (Zeiss E.) 
Fig. 4. A longitudinal section through the leaf of a young 
wheat-plant, on which uredospores had been allowed to ger- 
minate for forty-eight hours. The section passed through a 
stoma, cutting one of the guard-cells (omitted in the drawing) ; 
through the cut guard-cell is seen the germ-tube from an 
uredospore which had germinated on the epidermis. The 
tube had formed a slight swelling over the stoma, and then 
entered ; its end branches around one of the mesophyll-cells 
bounding the respiratory cavity. The nucleus of the distal 
guard-cell is very clearly seen. Orange-red granules are 
observed in the protoplasm of the germ-tube. 
In Fig. 5 (PI. XII) is a group of the teleutospores , obtained 
from a longitudinal section of the dry ripe straw of the wheat. 
The mycelium has now completely destroyed the cellular 
tissue, and its branches produce the two-celled elongated 
teleutospores, instead of the uredospores ; specimens can be 
obtained with both uredospores and teleutospores arising 
from the same matrix. In this stage the fungus was named 
Pticcinia. (Zeiss B.) 
Fig. 6 shows in greater detail two of the teleutospores 
from the above patch. As before, each arises as a swelling 
at the end of a hypha ; this club-shaped swelling becomes 
filled with dense protoplasm, and separated off from its pedicel 
by a septum. The young spore is then divided into two by a 
horizontal wall, and each of the two cells acquires a very 
thick hard coat, divided into several strata, as shown in the 
drawing. The colour also becomes much darker than before, 
the outer coats of the exosporium especially being sienna- 
brown ; owing to this the streaks of teleutospores on the wheat- 
leaf appear brown or nearly black, in contradistinction to the 
orange-red streaks of uredospores. These teleutospores, 
developed in the autumn as the wheat ripens, contain oily 
drops in the protoplasm, and the outer shells of the exosporium 
are cuticularised. Unlike the thinner walled uredospores, 
which are developed in the summer (July) and germinate 
Q % 
