Fig. 27.— Canker fungus spreading down from a branch. 

 This was photographed from a living specimen. The dark- 

 coloured cortex near the branch is dead. The lighter 

 coloured, above and below this, is alive. 



.' : f {;:» 



Fro. 28.— Spread of fungus down the branches. This 

 stem was taken from a young tree wliicdi had been fidh^d 

 and allowed to lie in the wi.od for a few mouths. 



