230 BULLETIN 193. 



tree, 30 or 40 years ago. This leader, as a dead, decorticated 

 object still projected 15 to 20 cm. above the point where the 

 healing process was going on (Fig. 85). One of the upper 

 branches at this point had become the leader. 



This old fracture of the main trunk years ago very probably 

 provided an opportunity for the entrance of the fungus. Most 

 conifers are provided with a quantity of free resin in the young 

 branches or shoots, or the growing portion of the trunk. As is 

 well known this resin flows freely from fresh wounds, and often 

 continues for some time from old ones. The presence of this 



89. Cross section of red spruce showing pockets from end view. 



resin and its free exudation from wounds is nature's most effect- 

 ive method of blocking the way to the entrance of timber 

 destroying fungi in the conifers. When the wound is small, or 

 the broken branch or shoot is young, the amount of resin forms 

 an effectual barrier against the entrance of this class of fungi. 

 Where the wound is larger, or the shoot is older, the process of 

 healing over requires many years, and the older portions of the 

 wood do not yield so great an amount of free resin. 



The broken shoot in this example was 5 cm. (2 inches) in 

 diameter. Healing began 20 to 30 cm. below the broken end. 

 After 30 or 40 years the dead prong still projected 15 to 20 cm. 

 above the healing surface, and probably never would have healed 



