32 RESEARCHES ON FUNGI 



was 9 mm. long, and possessed a perimeter at its base of G mm. 

 Hence, the area of hymenium for each square centimetre = 9x0x22 

 = 1188 mm. 2 approximately. Therefore, for 1 cm. 2 , =100 mm. 2 , 



we find that the specific increase = = 11*8 approximately. 



In most specimens of the fungus the tubes do not attain a length 

 of 9 mm. The specific increase is therefore usually less than 11 8. 

 By comparison with the results in the table given above, it may be 

 concluded that many Agaricinese have a larger specific increase than 

 Polyporus squamosus. However, this species has unusually wide 

 tubes. When the tubes are very narrow, as in the cases of Fomes 

 vegetus and F. igniarius, now to be discussed, it is found that 



Fig. fi. — View of part of the underside of a mature fruit-body of Polyporus squamosus 

 which was 2 ft. 2 in. across. The openings of the hymenial tubes are polygonal. 

 Natural size. 



the specific increase may be much greater than that in any of the 

 gilled fungi. 



Fomes vegetus. — The fruit-bodies are perennial and produce 

 a layer of tubes annually (Fig. 11). In the specimen examined it 

 was found that for one year there were 2080 tubes to 1 square cm. 

 The length of each tube on the average was 12 mm. and the 

 diameter - 17 mm. Hence, the area of the hymenium for each 



square centimetre = 12 ( — x 0-17 j x 2080 = 148:'>0-4 mm. 2 approx. 



Therefore, for 1 cm. 2 , =100 mm. 2 , we find that the specific increase 



= — - — = 148 approximately. In the specimen examined three 



