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black glazed paper. The fairy ring mushroom is one of the commonest species which grows on the lawns in Washington and vicinity. As many as twenty of these fairy rings have been found on the grounds of the Department of Agriculture in one season. In the earlier days, when superstition was more rife than at present, these rings were supposed to mark the places of the dances of the fairies. Another fanciful cause assigned for the production of the rings was that it was due to the effect of lightning striking the ground and burning the grass in a circle, and thus favoring the growth of fungi. Investigations, however, show that the fairy ring is due to a peculiar way in which the mycelium is produced, which begins at a central point, growing uniformly in all directions a few inches each year. After a while the central portion, being older, begins to die, and thus a small circular band is formed which each year increases in size, growing regularly on the outside and dying as regularly on the inside. The fairy rings are not always complete circles,—they are sometimes broken and often are crescent-shaped. This variety of mushroom is quite permanent, does not tend to decay as rapidly as some, and resists better than most varieties the attacks of insects. They, however, are very small as compared with the other common varieties.

Fig. 64.—Fairy Ring Formed by Marasmius oreades, an Edible Mushroom.—(Coville, Circular 13, Division of Botany.)

Puff-balls.—A typical mushroom known as the puff-ball is the variety