io8 Bi'itish UredinecB and Usiilae'ine^. 



<3 



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 Leptopucciniae 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 yean 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 Triticuni 

 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 



