30 PLANT DISEASES AND FUN(;i. 



ceeding changes follow each other in regular order. But this is not 

 all, since another system of reproduction is going on within the plant 

 tissues. Certain of the threads of the mycelium produce internally 

 larger globose bodies, sometimes called " resting spores," which 

 acquire a thick outer coat, and then remain dormant in the plant 

 stems throughout the winter, only germinating after a period of 

 rest. It is these "resting spores" which carry over the parasite to 

 the following spring, and awake to life and vigour just at the time 

 when young host-plants are ready to receive them. During the 

 winter these resting spores are concealed within the old herb-stems 

 which lie and rot upon the surface of the ground. In the spring, it is 

 assumed, that by the decay of the stems of the original host-plant the 

 resting spores are freed, and under the influence of spring rains 

 undergo their final change, like that of a chrysalis to an imago. The 

 contents of the globo.se body become divided into a number of seg- 

 ments, each of which is at length enveloped in a thin membrane, 

 and furnished at one extremity with a pair of vibratile cilia. When 

 the thick coating of the resting spore is ruptured, all the contained 

 zoospores escape, and are washed on to the ground, or wherever the 

 moisture will carry them, fully competent to carry on the process of 

 reproduction, by germinating upon the leaves of such young foster 

 plants as may be growing in their vicinity. By the means of these 

 two processes of reproduction, the conidia in the summer and 

 autumn and the resting spores in the spring, the perpetuation of the 

 species is assured. 



After a consideration of this life history, it will become manifest 

 that such a pest must be met and encountered, in no haphazard 

 manner, but with skill and perseverance. Burning all the debris of 

 old plants in the autumn will include the destruction of all the rest- 

 ing spores, and thus prevention will obviate the necessity of seeking 

 for a cure. 



By this time it will have become evident that there is only one 

 way in which the fungoid diseases of plants can be successfully 

 encountered, and that is by the patient acquisition of knowledge, 

 and a course of action based upon that knowledge. It can no longer 

 be maintained that the study of fungi is a waste of time ; it is no 

 longer possible to laugh at those who pursue the study as fanatics 

 and enthusiasts. The old cry of cui bono has no longer any potency, 

 for it is only by patient study, by the acquisition of knowledge, and 

 by the spread of knowledge of the life history and characteristics of 



