=Pileus:= At first globular, its edge connected to stem by the veil; then round convex, at length becoming possibly almost flat. Surface dry, downy, or even quite scaly, varying in color from creamy white to light brown. Diameter at full expansion, about three inches.
=Gills:= Unequal in length; pink when first revealed, becoming brownish, brown, purplish, and finally almost black.
=Stem:= Solid; of the color of the cap; paler and white in section, retaining the remnant of the veil in a permanent ragged ring.
=Taste:= Sweet and inviting, and odor agreeable.
=Habitat:= Pastures, lawns, and open rich soil generally.
=Season:= Late summer and early autumn, occasionally in spring.
[Illustration: PLATE V AGARICUS CAMPESTRIS.]
Doubtless a sufficient and satisfactory reason for the universal dignity which this species has acquired as "the mushroom" may be found in the fact that it is the only species prominently under cultivation, and almost the only one which is sure to respond to the artificial cultivation of its spawn in the so-called "mushroom bed." The "spawn" of the Campestris has thus become a mercantile commodity, duly advertised in the seedsmen's catalogues.
This so-called spawn is in truth nothing but the mycelium, or subterranean vine of the mushroom (see Plate 2), taken from the beds in which the mushrooms have been grown, or in which the mycelium has been cultivated. The cultivator simply prepares a "bed" to receive it--duplicating as far as possible the soil conditions from which it was taken, whether from foreign cultivation or his old manure-bed or stable-yard--a rich, warm compost of loam and horse-manure, this latter ingredient being a most important consideration, as the fungus in its several varieties, notably the larger, _Agaricus arvensis_, known as the "horse-mushroom," has followed the track of the horse around the world. These natural conditions having been even approximately fulfilled, will, within two months, generally reward the cultivator with a crop of mushrooms, which, with the continued ramifications of the mycelium permeating the muck as the yeast fungus permeates the home-made loaf, will insure a continual succession of crops for weeks or months, to be renewed spontaneously, perhaps, the following season.