2M 



BUJ.LETIN 193. 



growth of the fruit form may then be (jiiite 

 small, as in fianu'e 79, where it is but a small 



'J 



» 



78. — JJlcem oil t/unk of 

 TTiaple. 



protuberance, 1 to 2 cm. in diameter, and 

 showing no fruiting surface. This often 

 increases in size each year slowly until 4 to 

 5 cm. in diameter, when it may increase moi'e 

 rapidly and each year form a new fruiting 

 surface beneath. 



The young fruit form shown in the photo- 

 graph is on a trunk of a maple 10 cm. in 

 diameter. This was the only evidence that 

 the tree was diseased, all the other wounds 

 at fallen limbs having healed over. A sec- 

 tion of the trunk shows that the heart rot 

 had begun. It is in the first stages of the 

 disease and confined to a limited area, that 

 directly at the centre of the heart. There 

 is present here only the discolored area 

 which is characteristic of the other and 

 younger area in older stages of the disease, 

 described above. It is quite likely that the 

 functus enters at these slow healino^ wounds 

 where the lower limbs have fallen^ and that 

 in some cases the wounds mio'ht entirelv 

 Ileal over and imprison the mycelium before 

 the fruit bodies had an o])portunity to form. 

 That there was abundant op|)ortunity for 

 the mycelium of the funa"us to enter at 

 these wounds is shown by the evidence of a 

 large proportion of the young maple trees 

 in the mixed forest at Clearwater. 



I have alreadv called attention to the deei) 

 shade in the spruce woods where the tall 

 spruces overtop the bi-oad leaved trees, and 

 of the effect which this shade has in check- 

 ing foliage development on the younger 

 maples. Even on the young and middle 



