The best place for growing cultivated mushrooms is one where the light is excluded or diffused and where the temperature remains reasonably constant. Cellars, caves, and the artificial caverns made by quarrying are peculiarly well suited for the growth of different varieties of fungi, such as mushrooms.
The art of growing mushrooms is not easily acquired. The directions given by the best authorities may be rigidly followed and failure ensue. The skill of the grower appears to be born, not made, and those who have acquired the art succeed where theoretical knowledge fails. For cultural purposes, the Agaricus campestris is most universally employed.
Soil.—The soil best suited for the growth of mushrooms is one rich in decayed or decaying vegetable matter. Mushrooms are often found growing in localities where a log or stump has decayed or where the inorganic matter from the manure of cattle or horses has been distributed on the soil. Artificial beds for the growth of mushrooms are made up largely of organic manurial substances.
Spores.—Mushrooms are grown from spores. The mushroom produces a brown powdery material which consists of almost innumerable simple cells of ovate shape to which the term "spore" has been applied. A spore is not in the strict sense of the word a seed, but simply a cell which by proliferation produces the new fungus. Generally growers do not use these spores directly in seeding mushroom beds. Each complete spore, however, is, under favorable conditions, capable of proliferation or germination, producing a thread-like growth of a spider-web character which penetrates through the soil, prepared and manured, upon which a spore is germinated. This spider-*web-like growth, in the common language of mushroom growers, is called the spawn, more properly called the mycelium of the mushroom. When the conditions are favorable, there are formed on the threads of this mycelium small nodules, which are the earlier stages of the complete fungus itself. From the beginning of this growth until the final production of the mushroom two or three days or even a week may elapse. The earlier periods of this growth take place under ordinary circumstances, but the advent of a warm rain or other extremely favorable conditions causes the budding mushroom to grow at an enormously rapid rate. The mushroom may not be said to have a root, stem, and leaf, as is the case with an ordinary green plant, but is practically a single organism, assuming different shapes which are represented by the different varieties and species of growth.
Differing Varieties of Edible Mushrooms.—There is a very large variety of edible mushrooms differing in form, size, and shape from the Agaricus campestris. In the Washington markets there are four principal kinds of mushrooms which are found growing wild in the vicinity of the city. These comprise the common mushroom—Agaricus campestris, the horse mushroom—
