364) INTRODUCTION TO CETPTOGAMIC BOTANY. 



felling, or, if this be out of the question, impregnation with 

 such chemical substances as are destructive to the growth of 

 Fungi. Merulius lacrymans is perhaps the worst of these, 

 as its mycelium attracts moisture. A cellar which has long 

 been dripping from its prevalence, will soon become dry when 

 a strong wash of corrosive sublimate is applied. Several of 

 the sjjecies are capable of a certaiu degree of growth in sub- 

 terraneous localities, in consequence of which a number of 

 very curious forms occur. Another peculiarity is, that as the 

 hymenium is constantly deposited on the side which is turned 

 towards the earth, if a specimen be accidentally reversed the 

 hymenium gradually loses its own characters, assuming those 

 of the pileus, and the contrary. Specimens in a state of tran- 

 sition are often very puzzling. 



398. Attempts have been made to cultivate Boletus edulis, 

 and a species of Polyporus is produced by roasting the branches 

 of hazel-trees in Italy. The dense masses of mycelium belong- 

 ing to P. tuberaster are capable of being transported thou- 

 sands of mUes, and on the application of moisture will pro- 

 duce a crop of pilei, as has been proved more than once in 

 England. Polyporus fomentarius not only supplies Amadou, 

 but has been manufactured into coarse clothing ; and the 

 pounded pileus of P. igniarius is mixed by the Ostyacks with 

 snuff, whose narcotic qualities it is said to improve. 



6. Agaricini, Fr. 



Hymenium plicate, radiating from a common centre ; the 

 main divisions often connected by transverse processes, but not 

 so as to form definite pores. 



399. The only remaining group of Fungi, and that contain- 

 ing the noblest though not the largest species, is distinguished 

 by the gill-like folds which form the hymenium. In some 

 species of Paxillus, they not only separate with ease from the 

 substance of the pileus, like the tubes of Boleti, but they are 

 capable of being unfolded to a considerable extent ; in other 

 species, the substance which unites the two surfaces is so closely 

 combined with each, that any such separation is out of the 

 question. In the genus Trogia, however, there is a groove 

 along the outer edge ; and in Schizophyllum, the gills split in 



