FOMES APPLANATUS 137 



requirements of the fruit-bodies during their many years of 

 spore-producing activity. 



The Number of Spores in Fomes applanatus and Other 

 Basidiomycetes. The total number of spores liberated by a large 

 fruit-body of Fomes applanatus during the six months of its spore- 

 fall period is enormous far greater than that of Polyporus squa- 

 mosus or of any of the fleshy Agaricineae so far investigated and 

 of the same order as that of a large Giant Puff-ball (Calvatia 

 gigantea). This conclusion is based on the following facts and 

 considerations. 



(1) J. H. White, using my haemocytometer method, observed 

 that a Fomes applanatus fruit-body having a pored area equal 

 to about one square foot liberated 30,000,000,000 spores in 24 

 hours ; and he also observed that the length of the spore-fall 

 period was six months and that, during this period, the number 

 of spores liberated per day, as judged by the diurnal spore-deposit, 

 was very constant. 1 Granting, then, that 30,000,000,000 spores 

 were liberated each day for six months, the total number of spores 

 which the fruit-body liberated must have been approximately 

 182 X 30,000,000,000 or 5,460,000,000,000. 



(2) The total number of spores produced by a large fruit-body of 

 Coprinus comatus was calculated as follows. The number of spores 

 on O'Ol of a square millimetre of gill-surface was counted, and the 

 total area of the hymenial surface on all the gills was measured. 

 A simple calculation based on these data then showed that the 

 fruit-body had developed on its gills approximately 5,240,000,000 

 spores. 2 These spores, had they been left undisturbed, would have 

 been liberated in about 48 hours. It is clear, therefore, that the 

 total number of spores produced by a large fruit-body of Coprinus 

 comatus during the two days of its spore-discharging activity is only 

 about one-thousandth of the total number of spores produced by a 

 large Fomes applanatus fruit-body in six months. 



(3) By using a method essentially similar to that just described 

 for the investigation upon Coprinus comatus, I found that a Mush- 

 room (Psalliota campestris) about 4 inches in diameter produced 



1 J. H. White, foe. cit., pp. 139-142. 



2 A. H. R. Buller, Researches on Fungi, vol. i, 1909, pp. 82-83. 



