of varied colors and sizes, the insects issuing from which are wingless. When the trial is made, they will be found incapable of reproducing the warts they came from; they are, besides, all females. Again, we may see, in the spring, the ends of the limbs of the same oak bearing greenish-red tumors, which naturalists have long called oak-apples. They are also galls from which Cynips issue; these too, like the others, are incapable of reproducing the swellings from which they came; but they have wings, and are both male and female. Here, then, are beings totally different, if we study them separately as they come out from their nests. Now let us follow the experimenter, first observing that the insect of the root has been called Biorhiza, and that of the apple Teras. The Biorhizas escape from the roots on which they are hatched, and raise themselves up slowly and painfully, having no wings, to the ends of the branches of the tree. There they lay unfertilized eggs, and cause, by piercing the twigs, the oak-apples from which the Teras issue. On the other side, the Teras, escaping from their apple, copulate, and the fertilized female descends to deposit her eggs in the roots. The Biorhizas, therefore, are hatched from the eggs of the Teras, and the Teras from the eggs of the Biorhizas. Here, then, are two genera wholly distinct in habits, organization, and external characters, which are nevertheless derived each from the other, and which zoölogically ought to form only one. How could M. Adler have discovered these facts, except by experiment? When we remark that the Cynips are relatively high in the animal scale, we are justified in believing that a very great number of similar surprising facts may yet be found among lower forms.
I can not refrain from relating another life-history which is almost a romance. There is a hard sandstone in Provence, interspersed with friable strata, in which burrowing insects construct their chambers. A kind of bee, the Anthophorus, makes nests there and fills them with honey, on which it leaves its egg to float; then, finally, plasters up its chamber. Instead of Anthophores, entirely different insects come out from these nests—Sitaris, belonging to a group very remote from the bees. Let us see how they manage to substitute themselves for the legitimate proprietor of the nest. In the autumn the impregnated female of the Sitaris deposits her eggs in front of the sealed galleries of the Anthophorus. The young are hatched from these eggs, and lie in front of the closed doors, and thus remain in a mass, mingled with the dust and rubbish of the place, through the winter. In the spring, such of the bees as have reached their term come out from their prison. These earliest insects are all males; but, though precocious in being hatched, they are still tender to the changes of the weather, and remain half frozen and torpid in the dust along with
