216 



BULLETIN 193, 



A maple tree about 20 cin. (eight inches) in diameter in the 

 mixed forest at Clearwater had been affected by the Polyporus 

 igniarius for a number of years. The fruit body was several 

 years old, of a triangular shelving form, and 15 cm. broad. 

 Several entire sections of the trunk, one of them bearing the 

 fruit body of the fungus, were collected and shipped to Ithaca. 

 Cross sections of the tree present a very characteristic and 

 often beautiful marking of the wood due to the different stages 

 of decay and the coloration of the wood. The more advanced 

 stages of decay lie at the centre, the less advanced ones toward 

 the periphery. The sound wood at the periphery is limited 



from the decayed area 

 toward the centre by 

 a broad and irregular 

 discolored area. The 

 discolored area is of a 

 light brown color, and 

 this is farther sharply 

 defined from the pale 

 yellowish white area 

 outlined by a narrow 

 black line. The more 

 advanced stages of 

 decay, in this maple 

 tree advanced toward 

 the periphery in 

 separated columns, 

 showing on cross sec- 

 tion a radiating or 

 digitate figure. The 

 radiations or "fin- 

 gers," alternate with 

 dark areas which ex- 

 tend inward from the 



75. Section nf maple tree showing effect of 

 mycelium of Polyporus igniarius. 



periphery as shown in the photograph. Sometimes this figure 

 is quite regular around a portion of the margin, while other 

 portions are very irregular. The decay of the wood seems to 

 proceed in waves from the centre toward the periphery, so that 



