86 



DISEASES OF TREES 



are developed on the filamentous mycelium which clothes the 

 diseased plant, or foreign substances, in the form of Rhizoctonw 

 or otherwise 



The perithecia of this species have been discovered by Viala. 





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They form only on vines and fruit-trees that have been dead 

 and decayed for a long period. It is only in soil that has dried 

 slowly that they are to be found. Associated with bristling ap- 

 pendages bearing gonidia the perithecia appear partly on sclerotia 



