192 PLANT DISEASES 



are almost semicircular in shape, fixed to the trunk by a 

 broad base, and measure six inches to a foot across. 

 When actively growing the tubes exude water, which drips 

 away in considerable quantities, even in very dry weather. 



I 





Fig. 44. Polyporus hispidus. i, two plants much reduced ; 

 2, section through a fungus showing the pileus, a, and the tubes, 

 b ; 3, two basidia bearing spores, x 300. 



Every part of the fungus yields a deep yellow colour when 

 soaked in spirit or in an alkaline solution. 



Being a wound-parasite, the mycelium can only gain 



