PRELIM I XAKY OUSERVATIONS. 7 



All the true species of Boletus arc fleshy, but they are 

 closely connected with one of the largest genera of Fungi, the 

 Poll/port (Plate 16, fig, 1-C), which exhibit every gradation, 

 from great succulence to the hardness of wood, in their mul- 

 titudinous species. The scaly Polyporus (P. squamosus), so 

 common on ash; the hispid, ferruginous P. hispidus, which 

 abounds on apple-trees ; the coriaceous P. vei'sicolor, with its 

 velvety pileus and many-coloured zones, so common on stumps 

 and felled wood ; and the hard, hoof-shaped P. igmarins, to be 

 found everywhere in plum-orchards, — are examples of difterent 

 conditions familiar to us all. Multitudes of other forms 

 occur, distinguished by the presence or absence of a stem, 

 the complete attachment of the pileus to the substance on 

 which it grows, so that the whole plant consists of resupi- 

 nate pores, by the clothing of the pileus, by the nature of the 

 jiores, etc. Many of these are extremely common, and others 

 as rare, and some run so closely into each other that the spe- 

 cies are very difficult to distinguish. In a few foreign species 

 the pores are so large that they very closely resemble a honey- 

 comb, and in others, almost the whole plant is of a gelatinous 

 texture. Such also is the case in a rare British species of 

 the genus MeruHus, which contains the well-known Dry-rot, 

 MeruUus lacrymans (Plate 2, fig. 1), so destructive to our 

 ships and domestic buildings. The walls of the pores are here 

 mere veins, and there is a close connection with some of the 

 lower forms of the Gill-bearing Fungi. The Pore-bearing 

 Fungi are included under the common name of Polyporei. 



Occasionally the walls of the tubes or pores are broken up ; 

 and as this takes place in an early stage of growth, the whole 

 surface of these processes is covered with the fructifying cells, 

 or, in other words, with the hymenium. 



This paves the way to a third group of some importance, 



