GOLIATH BEETLE, AND PUPA CASE.
"This fine Goliathus," he would say, "has not long, probably, emerged from a hollow case of oval form, made of particles of earth agglutinated together by a secretion from the mouth of the larva, and concealed under the surface of the ground. Within that sepulchre it has left its cerements,—the shrivelled skin of the pupa, in which it had been wrapped up motionless like a mummy, for several weeks prior to its appearance as a glittering beetle. The construction of the oval cell was the last act of the larva, a thick, massy, heavy-bodied grub, which had fattened for years by feeding on the roots of plants beneath the soil. Four years passed away[69] while yon beetle lay on its side, darkly labouring at this occupation; and before that it was a minute egg for some weeks. The specimen before us cannot be far short of five years old."
No such thing: the witness is at fault: the Goliathus is not an hour old.
Take notice of the swarm of Gnats, which, like a dim cloud, are uniting in choral dance and song in the beam of the setting sun. Every member of the band that "winds his shrill horn," has had an aquatic before he had an aërial existence. A week was spent, in lobster-shape, with two breathing tubes on the summit of his body, in passing alternately from the bottom to the top of yonder stagnant pool, and then back from the top to the bottom. And a month was occupied in pretty nearly the same employment, but in another mask,—in fish-like form, with the star-tipped breathing-tube projecting from the side of the tail. But for some months earlier still it was a little lenticular egg, which was agglutinated with a number of others into an oval concave boat, that floated to and fro on the surface of the pool.
And there was something worth observing in that tiny skiff of eggs; for it did, in its artful construction, carry the evidence of time back to a former generation. The eggs individually and separately would have sunk to the bottom of the water; it was, however, essential to their life that they should be in contact with the air as well as with the water. Hence they were so arranged in the aggregate, that the mass should swim, though the constituent individuals could not. To effect this, the parent Gnat, resting on the calm surface of the pool, crossed her two hind legs, and laid an egg perpendicularly in the angle so made: others were added in succession, all maintaining the perpendicular position, all glued together by a cement that resists water, but so arranged, the crossed legs being still the mould, that the outline should be spindle-shaped, while the summits of the central eggs, being a little lower than those of the outer ones, gave a concavity to the boat. So buoyant was it when finished, and the mother's legs withdrawn, that even a drop of water falling full upon it from above, would have failed to submerge it. There it floated, week after week, and month after month, all through the winter, till the genial sun of spring hatched the fish-like larvæ to begin their wriggling existence beneath the surface.
Now may we not say with confidence, that the sounding-winged insect looks back to the pupa, the pupa to the larva, the larva to the egg-boat? And more, that the form of the boat,—a form so essential that it could not have lived without it,—looked back to the crossed feet of the mother-gnat, the impress of whose angle its extremities sustained?
Of course we might reason thus: but yet we should be at fault; for the ringing swarm of merry Gnats has been this very evening created.