hyphæ modified here and there to the accomplishment of various functions. Fungi, like other organisms, have two principal things to do—viz., to accumulate energy and to expend it; to grow and to produce fruit. The hyphæ of a fungus are, therefore, in ordinary cases of two sorts—nutrient hyphæ forming the mycelium, and fruiting hyphæ which make up the fructification. In what we term puff-ball, mushroom, we have simply the fructification—the fruiting hyphæ—all compacted together, while the mycelium lies hidden beneath the surface. When, however, we pluck the mushroom from its place, the mycelium may perhaps seldom be discovered. There are for this two reasons: first, the mycelial threads are generally tenuous and delicate in the extreme, and unless crowded together escape observation; and, secondly, once the fructification or colony of mushrooms is formed, the energy of the mycelium having passed above the surface, the threads vanish. Only in special cases, or where the fructification is unusually large, and the number of hyphæ converging at a single point in consequence very great, do we find root-like structures that are at once obvious and persistent. Fugacious as the mycelium thus appears, it is really in many—perhaps most—cases much longer-lived than the fructification it creates. Months—possibly in some instances years—elapse while the subterranean hyphal threads ramifying and spreading through myriad diminutive tunnels are ingathering to some single center those resources of nutriment and energy which shall at length break forth with a suddenness and volume utterly astounding. In my neighbor's yard, not long ago, appeared a succession of giant puff-balls one after another, sometimes two or three at a time, over an area of perhaps thirty by forty feet. In size the plants ranged from the dimensions of a goose-egg to that of a half-bushel, and the amount of matter raised above the surface was little less than one hundred pounds. The largest fruit seemed simply sessile, hardly attached to the substratum, while others, smaller, showed something like a tap-root, white, cord-like, extending a few inches downward—not a root, certainly, rather the undeveloped base of the ball itself. Whence had all this wealth of organic matter come, and what was the meaning of it all? The previous existence of a wood-yard on the locality affords probable explanation of the phenomenon. Through and through the accumulated detritus of the old wood-yard the mycelium of the puff-ball had literally threaded its way, developing perchance for years over an area of not less than twelve hundred square feet, restoring again for the moment to the kingdom of life and light organic matter which seemed fallen into ruin irretrievable.
Turning our attention now to the fructification, we shall find our mushroom to consist of the following parts: A short stalk.