32 RESEARCHES ON FUNGI 



was 9 nun, lonj^', and possessed a perimeter at its base of G mm. 

 Hence, the area of hymenium for each square centimetre = 9 x <> x -2 

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



11 88 

 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 1 1 S. 

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

 concluded that many Agaricinea; have a larger specific increase than 

 Foli/poruf^ sqitariiosus. However, this species has unusually Avide 

 tubes. When the tubes are very navroAV, as in the cases of Fames 

 vegetiis and F. i(/nl<i)''nis, now to be discussed, it is found that 



Fig. 0. — View of part of the underside of a matur(> fruit-liody of I'dlypoms nr/uamosug 

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

 Natural size. 



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

 trilled funiji. 



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 lenc^th of each tube on the averai^e Avas 12 mm. and the 

 diameter 0-17 iiiiii. Hence, the area of the hymenium for each 



square centimetre= 12 f "_" X ^'1' ) >^ -*^*"'^*-' = l-^'^-'^'-i nmi.- appri)x. 



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



14830-4 1 ,,,  . 1 T 4-U • • 1 »!, 



= =148 approxunatel}'. In the specimen exammed three 



