FIB DISEASES 



167 



and from the exterior this rot is identified bmthe rusty knots. 

 In the heartwood there are three distinct stages in the progress 

 of the decay. As the rot advances, the newly affected wood 

 is discolored and spongy, with occasional light brown spots. 

 This advance rot, as it is called, extends from two to six feet 

 beyond the distinctly red-brown disorganized wood. In more 



Fig. 25. — Fruiting-body of Echinodontium, tinctorium. 



advanced stages, the wood tm-ns red-brown and is soggy. The 

 annual rings are separated into sheets which appear as brown 

 cylinders one inside the other. Soon, however, the wood of 

 these partially destroyed rings is dissolved and the tree be- 

 comes hollow. The decay may proceed until only a thin shell 

 of sapwood remains. 



