prolonged hymenophore. They are vertical, simple, equal, respectively, or more frequently alternating with shorter gills. They are often evanescent and putrescent, sometimes liquefying altogether. Their color is usually different from the upper surface of the cap, not always similar to that of the spores borne upon them, at least in youth; with age, however, they usually assume the color of the mature spore. The change of color of the gills according to the age of the plant is very important in the study of the Agaricini; it accounts for the white gills of certain species in youth, the pink in maturity, and the brown when aged.

The end of the gill nearest the stalk of the plant is termed the posterior extremity; the opposite end, the anterior extremity. In most of the Agaricini the gills are unequal. Some extend from the margin to about half the space between it and the stem; others are still shorter.

THE VOLVA.

The volva is a membrane which envelops the entire plant in embryo, giving it the appearance of an egg. It originates at the base of the mushroom and furnishes it, during its fœtal life, with the means of support and nourishment. Its texture is so delicate that it generally disappears, leaving very little trace of its existence on the adult plant. In many of the volvate species this organ exists only so long as they are under ground, and some mycologists restrict the term "volvati" to such only as retain it afterwards. As the young plant expands it breaks through the top of this volva or wrapper, and, emerging, carries with it patches of the membrane on the upper surface of the cap. These are more or less prominent, numerous, and thick, sometimes irregularly disposed, sometimes regularly in the form of plates, warts, etc. At the base of the stem of the mushroom the remains of the volva are seen in the form of a sort of wrapper. This is more or less ample, thick, and ascending. It is called free when it is loose or easily detached from the stem, and congenital when it cannot be separated from it without laceration. In some species it is distinctly membranous, and in others floccose, and friable in character, sometimes appearing in ridges as a mere border, at others broken up into scales, and, as the plant matures, wholly disappearing. The volva is a feature of great importance in the study of the Agaricini, of the subgenera Amanita, Volvaria, etc.

THE MUSHROOM VEIL.

The veil is not a constant feature in the Agaricini, at least it is not always visible. When present it consists of a membrane which extends from the margin of the cap to the stem, veiling or protecting the gills. This membrane, called the cortina, has given its name to a numerous and important class of mushrooms (the Cortinarias). It is generally white, soft, slightly spongy, cottony, at times fibrillose or even slightly fibrous, again in texture comparable to the spider's web, and may be even powdery or glutinous. It exists intact only in the youth of the plant. It is not visible in the developing mushroom, at least while the cap is closely pressed against the stem, but as the cap expands the membrane extends and finally breaks, leaving in some species its remnants upon the margin of the cap and upon the stem in the usual form of a ring or a mere zone. When the stem is not ringed the veil rises high upon the stalk, stretches across to meet the edges of the cap, and is afterwards reflected back over its whole surface.

MUSHROOM SPORES AND MYCELIUM.

The spore is the reproductive organ of the mushroom. It differs from the seed of the flowering plant in being destitute of an apparent embryo. A seed contains a plantlet which develops as such. A spore is a minute cell containing a nucleus or living germ, the reproductive cell germ called by some authors the germinating granule. This in turn throws out a highly