CALYPTOSPORA GOEPPERTIANA 61 
which they completely fill, They are mostly divided by two 
crossed walls into groups of four cells, each provided with a 
germ-pore at its upper and inner corner. 
In the spring following their formation, they germinate in 
situ about May, sending out their basidia through the dead 
epidermis, and producing their basidiospores in the air. These 
are blown by the wind on to the just-starting shoots of Fir, and 
infect the young leaves, on which they produce the ecidia on 
yellow spots in two rows, one on each side of the midrib. The 
ecidia are cylindrical, white, with torn margin, }—1 mm. high, 
filled with orange spores, and when empty look like the remains 
of insects’ eggs. Their spores are soon ripe and can infect the 
young Cowberry shoots, but not the Fir. The diseased leaves 
soon turn yellow and begin to fall off during July; it is this 
early defoliation of the Fir that does the harm. 
There is obviously no cure except to remove and burn the 
infested Cowberry plants, and for the sake of prevention these 
should be searched for in the neighbourhood, when a plantation 
of Silver Fir or its allies is going to be made. There is no 
difficulty in detecting them on account of the peculiar appeatr- 
ance which they present. The disease is rare in this country, 
and is confined mainly to the moorland districts. 
These life-histories have been selected in such a way as to 
show, so far as could be done from British species, the remarkable 
variations that exist in the cycle of development and in the 
occurrence of the different spore-forms of the Uredinales. 
