210 



BULLETIN 193. 



The decay of the heart wood had reached an advanced stage so 

 that it was quite soft, and the moisture content was much less 

 than in healthy trees. The lessening of the water content of the 

 heart wood during the growth and spread of the mycelium caused 

 a shrinkage in the wood. This produced several radial checks 

 into which the mycelium had grown forming sheets of pure 

 mycelium, sometimes called "punk." 



POLYPORUS SULPHUREUS IMPRISONED IN A WHITE OAK. 



A white oak tree about 40 years old was growing quite close 

 by the side of a larger tree on the grounds of Cornell University. 



The tree leaned 

 slightly away from 

 the larger one and 

 there was a one 

 sided development 

 of the branches 

 induced by strong- 

 er illumination 

 from that side. 



' The tree was 

 felled in order to 

 see if there was a 

 correspo n d i n g 

 asymmetry in 4he 

 annual growth of 



the trunk which 



67. Section of living oak with imprisoned . ,, , :*-. 



mycelium of the sulphur polyporus. might be mamtest 



in the excentric 



position of the annual rings. Before cutting the tree down there 

 was no evidence that it was diseased. The trunk to all external 

 appearance was sound. There were no broken limbs, no wounds, 

 visible. On cutting the trunk into sections to study the annual 

 rings, the heart wood through a large part of the trunk pre- 

 sented unmistakable evidences of partial decay following many 

 of the annual rings and along by the medullary rays. The 

 wood in these areas was being disorganized by the mycelium, 

 and the latter forming the incipient stages of punk. 



