Omphalos: An Attempt to Untie the Geological Knot

by Philip Henry Gosse

"The attachment of this affectionate mother is not confined to her eggs. After the young spiders are hatched, they make their way out of the bag by an orifice which she is careful to open for them, and without which they could never escape; and then, like the young of the Surinam toad (Rana pipa), they attach themselves in clusters upon her back, belly, head, and even legs; and in this situation, where they present a very singular appearance, she carries them about with her, and feeds them until their first moult, when they are big enough to provide their own subsistence."[94]

I waive the argument derived from the fact of the apparent necessity of the mother's care for the new-born young. But the mother's care is indispensable to the appearance of the young at all; not only because the eggs are the produce of her ovary, but also because the envelope which protects them is the produce of her spinning-glands.

There is a furry moth, by no means uncommon, known to collectors as the Gipsy (Hypogymna dispar), the eggs of which require to be protected by an elaborate covering, either from extremes of temperature, from light, or from certain electric conditions of the atmosphere. The protection is afforded at the expense of the hair which clothed the mother herself. Her ovipositor is furnished with a pair of nippers, by means of which she plucks off her own hairs, and makes with them a flat cushion on the surface of a leaf. On this she deposits her eggs in successive layers; and when the full number is laid, she covers them with a roof of hair, slanting downwards and outwards from an apex, so artfully arranged, like the thatch of a cottage, as effectually to throw off water; each layer of hairs overlapping the preceding, and all preserving the same direction, so that, when finished, the work resembles a smooth and well brushed piece of fur.

If, then, a patch of eggs newly-created had been subjected to our inspection, we should have found them snugly protected by their conical roof of thatch; and when we came to examine the thatch microscopically, we should have found it composed of the hairs of Hypogymna. And thus again we should have an indubitable and yet deceptive record of a preceding existence.

The numerous species of the genus Coccus, to which we are indebted for cochineal, lac, and other products valuable in commerce, afford me an illustration of my argument, more striking than any of the above. In the case of the lac insect (C. lacca), for example, the female resembles a little hemispherical scale on the twig of a tree. At a certain period of her life, a pellucid, glutinous substance begins to exude from the margins of her body, which by and by completely covers it, cementing her firmly to the branch, from which she never afterwards moves. She now proceeds to lay her eggs, which one by one as they are extruded are thrust under her, between her abdomen and the surface of the branch. The result of this is, that when the whole are laid, they occupy pretty nearly the same position in relation to the mother as they did before, with this exception, that the abdominal integuments, which before were beneath them, are now above them, and are in close contact with those of the back, so that both together make a double, but still a thin, arched roof over the heap of eggs, which are thus protected till the hatching of the young, when they eat their way out of their long dead mother.

Let me now make my usual application. You say the Coccus was created not an adult insect, which would involve the prochronic stages of its metamorphosis, but as a germ, that is an egg (for the germ of an insect is an egg, and nothing else): well, here is a batch of Coccus-eggs just created, covered with the scaly roof which is necessary to their existence. But this scale is not a record of the mother, but the mother herself, a prochronic mother, of course!

Other genera of this wonderful class of animals yield us evidences of a somewhat different character, in the structures which the parents form for the reception of their eggs.

One of the most complex and elaborate pieces of mechanism found in any animal organ is the ovipositor of the Sawflies (Tenthredinidæ). I cannot here describe it at length; it may suffice to say that it consists of two saw-plates, working separately and in opposite directions, the teeth of which are cut into finer teeth; and two supporting plates, very similar to the saws in shape and appearance. The whole flat side of the saw is, moreover, covered with minute sharp points, which give the action of a rasp to the instrument, in addition to that of saw.

By means of this complicated apparatus the parent fly cuts a groove in the twig of the proper shrub, say, a rose-bush. When it is made, the plates are slightly separated, and an egg is laid in the groove. The saw is now withdrawn, and a frothy secretion is deposited, which appears to be intended, by its hardening, to prevent the growth of the wood from closing upon the egg, before the time of hatching arrives.

If, then, any of the species of Tenthredo had been called into primal existence as an egg, it must have been within such a groove as this; and the groove, if carefully examined, would have presented evidences of having been formed and filled by the curious implement of the parent fly.