PRELIMINARY OBSERVATIONS.

7

All the true species of Boletus are fleshy, but they areclosely connected with one of the largest genera of Fungi, thePolypori (Plate 16, fig. 1-6), which exhibit every gradation,from great succulence to the hardness of wood, in their mul-titudinous species. The scaly Polyporus ( P. squamosus), socommon on ash; the hispid, ferruginous P. hispidus, whichabounds on apple-trees; the coriaceous P. versicolor, with itsvelvety pileus and many-coloured zones, so common on stumpsand felled wood; and the hard, hoof-shaped P. igniarius, to befound everywhere in plum-orchards,—are examples of differentconditions familiar to us all. Multitudes of other formsoccur, distinguished by the presence or absence of a stem,the complete attachment of the pileus to the substance onwhich it grows, so that the whole plant consists of resupi-nate pores, by the clothing of the pileus, by the nature of thepores, etc. Many of these are extremely common, and othersas rare, and some run so closely into each other that the spe-cies are very difficult to distinguish. In a few foreign speciesthe pores are so large that they very closely resemble a honey-comb, und in others, almost the whole plant is of a gelatinoustexture. Such also is the case in a rare British species ofthe genus Merulius, which contains the well-known Dry-rot,Merulius lacrymans (Plate 2, fig. 1), so destructive to ourships and domestic buildings. The walls of the pores are heremere veins, and there is a close connection with some of thelower forms of the Gill-bearing Fungi. The Pore-bearingFungi 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 wholesurface 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,