"If one should take a full-grown mushroom after the under surface of the cap has become exposed by the breaking away of the annulus, twist the stem until it breaks away from its attachment to the cap, or cut it off short, and then place the cap gill surface downward on a sheet of white paper, there will be found in the course of twenty-four hours, more or less, a print. ...The print obtained is a fairly good reproduction of the projected form of the gills, being composed of a mass of brownish-black powder which has fallen from the gills themselves. It is... for the production of this powdery mass that the mushroom, as we know it, is formed. The brown powder consists of innumerable minute simple cells in the form of ovate bodies, termed "spores." ...They are equivalent to the green powdery substance produced by moulds which grow upon bread, cheese, and the like. Their function is that of reproducing the mushroom, but they should not be termed seeds. ...The entire gill surface is the "hymenium," or spore-bearing layer."