108 British Uvredinee and Ustilaginee. 
nor will they if they have once become thoroughly dry. 
The same method is to be adopted with the uredospores, 
and the same precautions observed. With regard to the 
teleutospores, certain modifications of the above are neces- 
sary. If one of the Leptopucciniz is to be examined, all 
that is requisite is to cut up one of the sori and place the 
fragments in a drop of water, and in a few hours the pro- 
mycelia will be developed. Those species which have a 
prolonged period of rest in their life-history, it is, of course, 
useless to attempt to germinate except at the proper season 
of the year. Suppose it is desired to observe the germina- 
tion of P. graminis, in the autumn some specimens of mil- 
dewed straw must be procured, and preserved through the 
winter, I have always found the best plan is to tie them 
up in a bundle and keep them out-of-doors, so that they 
are exposed to the same vicissitudes of temperature and 
moisture as would happen to them in a state of nature ; 
for it is obvious that if they be kept throughout the 
winter indoors, they will not only be maintained at a 
higher temperature, but also will become more completely 
dried than is natural to them. Under such circumstances 
they neither germinate so freely nor so uniformly as they 
do when they have passed the winter in the open air. 
Specimens of P. graminis may be obtained on Triticum 
repens, in February or March, from the immediate vicinity 
of any barberry bush, and these will be found to germinate 
very readily. Having obtained the material, in March or 
April, however it may have been preserved, in order to get 
it to germinate all that is required is to place it in water. 
If some of the spore-beds be cut into pieces about one- 
eighth of an inch (2 or 3 mm.) across, and placed in water 
in a watch-glass, under the bell-glass, the process of germi- 
nation soon commences, perhaps in twelve hours, perhaps 
longer, according to the manner in which the material has 
