PREAMBLE. 16

named, and that is the color of the spores produced by each species. When any of the gill-bearing fungi are expanded and near maturity, the gills will be observed to vary in color—some being white, and others of almost any tint of gray, or brown, to black. But the color of the gills must not be relied upon as the color of the spores, for in some cases the gills may be colored, while the spores remain white. To ascertain accurately the color of the spores, the stem should be cut off close to the underside of the cap, and the severed cap should be placed, with the gills downward, upon a sheet of paper, and left in that position all night. In the morning, the spores will have fallen from the gills onto the paper, outlining the form of the cap and showing the radiating lines of the gills. If the spores are believed to be white or light-colored, opaque black paper should be used; if very dark or black, then white paper should be used. This enables