We see here about us swarms of these busy elves in obedience to their own peculiar mischievous promptings. What whispers this glittering midge to the oak twig here to which she clings so closely? We may not guess; but if we pass this way a month or so hence, what a beautiful response in the glistening, rosy-clouded sponge which encircles the stem! "But this sponge is not pretty enough by half," exclaims a rival fairy. "Wait until you see what yonder sweetbrier rose will do for _me_." Hovering thither among its thorns, she imparts her spell, and, lo! within a month the stem is clothed in emerald fringe, which grows apace, until it has become a dense pompon of deep crimson--a sponge worthy the toilet of the fairy queen herself! Who shall still say that the fairy is a myth! These two fairy sponges are familiar to us all, at least to those of us who dwell for even a small part of the year in the country, and use our eyes. Indeed, we need go no farther than our city parks, or even our "back-yard" gardens, to find at least one of them, for the sweetbrier is rarely neglected by this particular fairy. So many specimens of both of these sponges have been sent to me by "Round Table" correspondents and others that I have begun to wonder how many of those other young people who have seen them and kept silence have wondered at their secret. The two fairies which are responsible for these sponges have been captured by the inquisitive scientist, and have had their portraits taken for the rogues' gallery, and now we see them stuck upon tiny little three-cornered pieces of paper, and pinned in the specimen case as mere _insects_--gall-flies. The one is labelled _Cynips seminator_, the other, _Cynips rosæ_. [Illustration: A. One of the points detached. B. Section of the base. C, D. Cynips emerging.] And now the prosaic entomologist proceeds to supplant fact for fancy. This gall-fly is a sort of cousin to the wasps, but what we would call its sting is more than a mere sting. Like a sting, it seems to puncture the bark or leaf, and at the same time probably to inject its drop of venom; but at the same time it conveys to the depths of the wound a tiny egg, or perhaps a host of them. One gall-fly is thus a magician in chemistry, at least, for no sooner are these eggs deposited than the wounded branch begins to swell and form a cellular growth or tumor about them, the character of this abnormal growth depending upon the peculiar charm of the venomous touch--to one a tiny coral globe, to another a cluster of spines, to another a curved horn, and to our cynips of the white or scrub oak a peculiar globular, spongy growth which completely envelops the stem, sometimes to the size of a small apple. In its prime it is a beautiful object, with its fibrous, glistening texture studded with pink points. But this condition lasts but a few days, when the entire mass becomes brownish and woolly, which fact has given this insect the common name of "wool-sower."