THE CLASSIFICATION OF FUNGI 27 



circular, in other examples angular in outline. If a species of 

 Boletus is examined, the hymenium, situated on the under surface 

 of the cap, presents the pinhole appearance described above ; now 

 if a median section is cut through the cap and down the middle of the 

 stem, the true nature of the hymenium can be studied. It will be 

 seen to consist of myriads of closely packed tubes standing end on, 

 one end of each being attached to the cap, the other end forming 

 part of the hymenium, and with its end open. It will be further 

 observed that the general mass of tubes forming the 'hymenium can 

 be easily separated from the flesh of the cap, and furthermore, that 

 with a little care the component tubes can be separated from each 

 other. Finally, the true hymenium or spore-bearing surface lines the 

 tubes, the basidia with their spores projecting into the cavity. 

 If a spore-print is made, by placing the surface of the hymenium 

 of a Boletus on paper, and allowing it to remain until the spores liave 

 fallen, it will be seen that the little heaps of spores deposited on the 

 paper will correspond exactly in shape and size with the pores in 

 the hymenium of the specimen used. 



The above explains the most typical structure of the hymenium 

 met with in the Polyporacea?, a word meaning literally many pores 

 or small openings. As would be expected, there are many departures 

 from the typical form. Nowhere else than in Boletus do the tubes 

 separate readily from the flesh of the cap, neither can the individual 

 tubes be separated from each other, yet the conception of tubes is 

 dominant throughout the family. In species of Boletus the tubes 

 are sometimes half to three - quarters of an inch long, whereas, 

 taking the other extreme, as presented by the genus Merulius, of 

 which M. lacrymans, or " dry rot," is perhaps the best-known 

 representative, the tubes are exceedingly shallow, or practically 

 non-existent, being reduced to very shallow pits, outlined by 

 slightly raised ribs or veins, anastomosing to form an irregular net- 

 work. Hence, whenever the surface of the hymenium presents a 

 porous or pitted appearance, it is highly suggestive of the family 

 Potyporacese. 



To this family belong the hard, woody, bracket-fungi, many of 

 which are perennial. There are great extremes of structure met 

 with in the family, ranging from structures resembling an agaric, 

 in having a fleshy cap supported on a central stem, and having the 

 hymenium inferior, or situated on the under surface of the cap, 

 to thin membranes spreading over bark or wood, and having the 

 surface slightly pitted, resembling in appearance a long past attack 

 of smallpox. 



Merulius is the genus connecting PolyporacccB \\'ith the next family 

 Hydnaceae, through the genus Phlehia. 



