spore- Ciiltiwe. 1 09 



been preserved, and according to the temperature of the 

 atmosphere at the time the experiment is made. I never 

 remember having seen any teleutospore germinate if the 

 temperature within the bell-glass was below s'' C. Germina- 

 tion is very partial and very slow at 8" C, but at from 10^ 

 to 15^ C. it is both vigorous and rapid. The germination 

 can be recognized to have taken place, if it be at all free, by 

 the naked eye ; the clusters of spores will then be seen to be 

 surrounded by an opalescent, hazy cloud, which, when 

 placed under the microscope, will be found to consist of 

 myriads of promycelia. A very convenient method of 

 preserving material on grasses — such, for instance, as Uro- 

 inyces pocs, which occurs on the leaves of the grass that in 

 the ordinary course of events become disintegrated by 

 decay daring the winter — is to gather a small bundle of 

 affected leaves, attached to the stems, place this bundle in 

 a flower-pot just as if it were a living plant, to cover the 

 flower-pot with a bell-glass, and keep it out-of-doors in a 

 shady place all winter. There will be enough moisture in 

 the atmosphere to prevent the material from being injured 

 by desiccation, but not enough to allow the teleutospores 

 to germinate until they are purposely placed in water. 

 The bell-glass will protect the grass from injury by wind 

 and weather ; so that when spring comes you will have 

 abundance of material ready to hand, in excellent condi- 

 tion for germination, which you can induce at pleasure, by 

 merely soaking it in water. The same method may be 

 conveniently adopted with those species which occur on 

 leaves, and in which the spores are lost by their decay in 

 the ordinary course of events. The Melampsorae on willow 

 and poplar may thus be kept out-of-doors under a bell- 

 glass with great facility. 



With those species which occur on leaves of plants 

 which have a very perishable foliage, it is necessary to 



