SPORE-DISCHARGE FROM POLYPOREAE 107 



period of several months' duration. It is now easy, therefore, to 

 explain the failure of Atkinson and other mycologists to find the 

 spores on the basidia of our Fomes : they all searched at the wrong 

 season of the year ; they cut sections through the hymenial tubes 

 in the autumn instead of in the spring. 



Thanks to the kindness of Dr. Faull, I have been able to observe 

 for myself that Fomes fomentarius does actually liberate its spores 

 in the spring. In order to show me this phenomenon, Dr. Faull 

 took me, on May 26, 1919, at Toronto, on an excursion into the 

 little valley which is spanned by the new viaduct. There, upon a 

 bank at the edge of a wood, were growing a number of ancient 

 Birch-trees (Betula, lutea) which were far past their prime ; and 

 from the trunk of one of them, about 2 feet above the ground, 

 projected several of the characteristically hoof-shaped fruit-bodies 

 of Fomes fomentarius. These fruit-bodies each contained a series 

 of annual layers of very fine hymenial tubes and, according to 

 Dr. Faull, were about six years old. As we approached the tree- 

 trunk, it became obvious that the fruit-bodies were producing and 

 liberating their spores ; for a white spore-cloud, like fine smoke, 

 was being given off beneath each one of them. This spore-cloud 

 could be easily discerned at a distance of 10 feet and it was slowly 

 being carried away by slight lateral currents of air. It thus exactly 

 resembled the spore-cloud of Polyporus squamosus which I described 

 in Volume I of this work. 1 We watched it for some minutes, but 

 it grew neither thicker nor thinner except in so far as it was affected 

 by slight changes in the speed of the air-currents. A number of 

 spores had settled near-by on the bark of the tree and upon the 

 tops of the fruit-bodies themselves, to which situation they had 

 doubtless been carried by slight upward movements of the air 

 during very still weather. The thickness of the white spore- 

 deposit suggested that the liberation of spores from the fruit-bodies 

 must have been going on for several previous days and nights. 



In most Hymenomycetes, as soon as the gills, tubes, spines, 

 etc., have come into existence, the associated hymenium imme- 

 diately proceeds with its development, which only ceases after 

 all the spores have been liberated. Fomes fomentarius, with its 

 1 Vol. i, 1909, pp. 89-93. 



