or stem, crowned with a cap, the pileus. This cap consists of an expanded disk, bearing on its lower surface hundreds of radiating plates, the gills or lamellæ, with sharp edges and delicately 
Fig. 2.—Section of the Lamellæ of common Mushroom. tinted, velvety sides. Cut a section perpendicular to the course of these plates or gills, and we have a comb-like structure which under a good lens presents the appearance portrayed in Fig. 2. Under still better lenses we may discover on each gill-section a marginal row of rather large cylindric cells, each bearing at its summit a pair of smaller cells manifestly formed by abstriction from diverging branches of the larger cell (see Fig. 3). The small cells are the spores, and the supporting cell but the terminus of an extended and much-branched hypha, which has blended with a myriad like itself to form stalk and cap and gill of our completed mushroom. That is the whole structure, and yet from such simple machinery behold what wealth and variety of form and style come forth! Other modes of spore-production there are to be hereafter seen, but that described is characteristic 
Fig. 3.—Schizophyllum commune. cross-section. of the vast majority of those greater fungi which occupy the shadows of our world. To begin with, there are hundreds of species of agarics, fungi like the mushroom, differing from each other in matters of form and color chiefly, the attachment of stipe and gills, the stability and instability of the entire structure. Some, as the "ink-caps" (Coprinus), spring in the night and vanish in inky dissolution ere the sun ascends to midday; others, as the little woolly fungus with cleft gills (Schizophyllum), so common on fallen branches everywhere, survive the storms of many seasons and outlast the substratum on which they grow. Fig. 3 shows the elegant curvature of the cleft gill-plates, and the order in which they appear. New ones are constantly intercalated between those already formed.
In all these the lamellæ run out in rays and remain quite gen-
