140 RESEARCHES ON FUNGI 



corresponding area of the Mushroom. I found that a wild Mushroom 

 about 4 inches in diameter has a hymenial area of about 1 33 feet 

 and produces about 16,000,000,000 spores. 1 Now White's large 

 Fames applanatus fruit-body had a pored area of about 1 square 

 foot. It is therefore clear that the hymenial area of the Mushroom 

 is only slightly larger than the area of the under side of the Fomes. 

 I showed in Volume I that in Fomes applanatus (=F. vegetus), 

 owing to the disposition of the hymenium in the inside of very 

 fine closely -packed tubes, with a tube length of 12 mm. the specific 

 increase of hymenial surface is 148, i.e. that a Fomes applanatus 

 fruit-body with a tube depth of 12 mm. and a pored area of 

 1 square foot has a hymenial area of about 148 feet. 2 Now in 

 some large fruit-bodies, e.g. the one shown in Fig. 48, p. 131, the 

 tubes may be 18 mm. deep or even deeper. Let us assume that 

 White's large fruit-body had a tube depth of 18 mm. Then the 

 specific increase of hymenium would be 220, i.e. the hymenial area 

 would be 220 square feet. We therefore see that : 



The hymenial area of the Fomes 220 



~ . "I *Z 



The hymenial area of the Mushroom 1-33 



i.e. that White's Fomes applanatus fruit-body had a hymenial area 

 about 165 times greater than that of our Mushroom. 



Now let us imagine a Mushroom so big that it has a hymenial 

 area not of 1-33 feet but of 220 feet, i.e. a hymenial area equal to 

 that of White's Fomes applanatus. How many spores would it 

 produce ? Since a Mushroom with a hymenial area of 1-33 pro- 

 duces, as we have seen, 16,000,000,000 spores, a Mushroom with 

 220 feet of hymenial area would produce : 



220 16,000,000,000 

 jTjjjj x ~ ~~i ~~ = 2,640,000,000,000 spores. 



Now the Fomes applanatus fruit-body with a hymenial area of 

 220 square feet produced, as we have seen, about 5,460,000,000,000. 

 This number is only about twice that obtained for the Mushroom, 

 i.e. is of the same order as that number. 



1 Vide infra, Chap. XIII, Section : " The Spore-discharge Period and the 

 Number of Spores." 



2 Vol. i, 1909, p. 32. 



