SPORE-DISCHARGE FROM POLYPOREAE 113 



The Spore-fall Period of Fomes igniarius. Fomes igniarius 

 frequently attacks living deciduous trees in both Europe and 

 North America. In Central Canada and the adjacent parts of 

 the United States its fruit-bodies are frequently found on Poplars. 

 At Winnipeg 1 have noticed them especially on Populus tremu- 

 loides Michx. where they project from the bark of the tree-trunk 

 at the base of the stubs of 

 lateral branches (Fig. 40). 

 The fruit-bodies grow slowly 

 but may attain an age of 

 20-30 years. 



At my request my col- 

 league, Dr. G. R. Bisby, 

 investigated Fomes igniarius 

 during the summer of 1921 

 with a view to determining 

 when the fungus discharges 



FIG. 39. Fomes fomentarius. The 

 backs of three fruit-bodies A, 

 B, and C, one, two, and three 

 years old respectively ; to show 

 the relation of a fruit-body 

 with the mycelium in a Birch 

 tree. The mycelium in each 

 tree burst through the birch - 

 bark only in the area a. The 

 fruit-body began its develop- 

 ment at a and then grew down- 

 wards, tending to take on a 

 conical form but being pre- 

 vented from doing so by the 

 presence of the tree -trunk 

 against which it came to press. 

 It became so firmly adherent 

 to the tree-trunk that when it 

 was forcibly broken away 

 therefrom, as shown at b, it 

 carried with it a thin outer 

 sheet of the birch-bark (cork), 

 which is easily recognisable 

 in B and C by the lenticels. 

 However many years a fruit- 

 body may continue its growth, 

 its connection with the 

 mycelium in the tree-trunk 

 is only via the hyphae in the 

 small area a. Fruit-bodies 

 collected near the Lake of the 

 Woods, Central Canada. J 

 natural size. 



VOL. II. 



