238 



Bulletin 193. 



An injury resulting from this kind of fractures leaves a long and 

 slivered end some distance from tlie point where healing takes 

 place. It must be a number of years then l)efore the healing 



process can advance so far 

 as to cover tlie fracture. 

 In this instance over thirty 

 years elapsed. The broken 

 and slivered end of the 

 sapling offered the most 

 favorable lodgment place 

 for spores of fungi, and 

 for the accumulation of 

 detritis resulting from tlie 

 constant weatherino; of the 

 exposed surface. In these 

 places moisture is also con- 

 served. The conditions 

 presented are favorable 

 for the germination of the 

 spores and entrance of the 

 mycelial threads. Is o moro 

 favoral)le infection court could be provided whereby the fungus i^ 

 enabled to enter the heart wood. 



From this point of in- 

 f e c t i o n the mycelium 

 spreads both ways down 

 the old trunk of the sap- 

 ling, and upward in the 

 branch whi^-h forms the 

 newl V estal)li8hed leader. 

 The |)r()gress of the fun- 

 ii; u s is con]i)arativelv 

 slow, and the disorgani- 

 zation of tlie wood ac- 

 companies it. The slow 

 o-rowth of the mvcelium 

 is probably due to several causes, the resistance which it meets from 

 the wood, the action of tannic acids in the heart wood, as well as to the 



69. — Section of oak sfiowing dead scvpUng stage 



near center. 



70. — Section of oak showing slivered end of 

 broken sapling. 



