Let us, once April is here, detach and lay open this strange appendage. It is hollow, and full of an incomparable downy wadding; no feather-bed or eider-down could boast of so fine, so white a filling. In the midst of this magnificent eider-down some ovoid beads are scattered, some white and others [[301]]tinged with a ruddy brown. These are the eggs. The new-born insects are swarming amongst them, higgledy-piggledy; some are bare and brown, some are more or less speckled with white, according to the more or less advanced state of the coat.
On the other hand, let us watch the Dorthesia idly roaming about the spurge. At long intervals we shall see emerging from the orifice at the end of the padded pocket a young Louse, handsomely clad, and nimble in his movements, who chooses his place beside his mother and settles down, plunging his bill into the juicy bark. He will not stir again until the well is dry. Others follow him from day to day; and this goes on for months on end!
If we were guided only by these observations we should conclude that the mother was viviparous, given to dropping, here and there, living offspring, all ready dressed. Nothing of the kind: we have just found in the thickly-quilted pocket both eggs and young. Moreover, the laying and hatching of the eggs may be witnessed without difficulty.
In a glass tube provided with a sprig of spurge I segregate a few mothers whose [[302]]terminal wallet I have removed. Laid bare, the insect’s hind-quarters have no further secrets from us; I see, sprouting from them, a sort of white mildew, like an unshaven beard. This is the waxy secretion that sprouts from the insect’s hind-quarters, producing, instead of tassels, filaments of extreme fineness. It is thus that the down which fills the wallet must be produced. Presently, in the midst of this tuft of down, an egg appears, like those which we obtained by breaking into the maternal treasury.
This method enables me to estimate the size of the clutch. Two Dorthesiæ stripped bare behind and isolated, with provisions, in a glass tube, produced, in thirteen days, thirty eggs, or fifteen apiece, or rather more than one egg daily. As the process of laying continues for nearly five months, the total number of eggs for a single mother must be nearly two hundred.
The eggs hatch in three or four weeks’ time. The hatching is announced by a change in the colour of the egg, which from white becomes a bright reddish-brown. On leaving the egg-shell the infant Louse is reddish-brown and absolutely naked. Its appearance [[303]]is that of a very tiny Spider, the more so as its long antennæ look very like a fourth pair of legs. Before long, four longitudinal rows of tiny white tufts appear on its back, with bare spaces between them. This is the beginning of the waxen mantle.
The protracted period of egg-laying, which continues for four months or more, the comparatively quick hatching, and, finally, the gradual exudation of the Louse’s clothing, explain why white eggs and reddish-brown eggs, with naked youngsters and others more or less clothed, are found simultaneously in the maternal pouch. This pouch is a warehouse in which the Louse’s eggs are collected for months together.
Inside the pouch, in the depths of its luxurious padding, the young Lice are born, grow up, and clothe themselves in wax before risking the dangers of the open. The mother gently carries them from twig to twig of the spurge without troubling herself as to those that emerge from her pouch. One by one, as they feel themselves strong enough, they migrate, when their time has come, to settle down in the neighbourhood. The exit from their home is always open; [[304]]they have only to force their way through the barrier of down.
The Narbonne Lycosa carries her family about with much less tenderness and security. There is no shelter on the back of the Gipsy Spider, no safeguard against falls, which are frequent in such a scramble. The Dorthesia, more happily inspired, makes a box of the skirts of her mantle and a downy bed of her caudal tufts. To find an equivalent method we must go back from the Spurge-louse to the first-born of the Mammifers—Kangaroos, Opossums and others—who rear their young in a pouch formed by a fold of the skin of the abdomen. Coming before its time, the shapeless embryo fixes itself on the teat and completes its development in the maternal pouch or marsupium.
Let us make use of this term to denote the Dorthesia’s pouch. There is a great similarity between the two wallets, although the insect is superior to the mammal in this respect: Life often begins with excellence in the lowly and ends with mediocrity in the strong. In the original device of the marsupium [[305]]a Louse has done better than the Opossum.