The earthen pot is exactly filled by its contents, without the slightest interval along the line of junction. This detail tells us the worker's method. The jar is moulded on the provisions. After the food-pellet has been formed in the ordinary baker's fashion and the egg laid in its hatching-chamber, the Bolbites takes some armfuls of the clay near at hand, applies it to the foodstuff and presses it down. When the work is finished and smoothed to perfection with indefatigable patience, the tiny pot, built up piecemeal, looks as though made with the wheel and rivals our own earthenware in regularity.
The hatching-chamber, in which the egg lies, is, as usual, contrived in the nipple at the end of the pear. How will the germ and the young larva manage to breathe under that clay casing, which intercepts the access of the air?
Have no fears: the pot-maker knows quite well how matters stand. She takes good care not to close the top with the plastic earth which supplied her with the walls. At some distance from the tip of the nipple, the clay ceases to play its part and makes way for fibrous particles, for tiny scraps of undigested fodder, which, arranged one above the other with a certain order, form a sort of thatched roof over the egg. The inward and outward passage of the air is assured through this coarse screen.
One is set thinking in the presence of this layer of clay, which protects the fresh provisions, and this vent-hole stopped with a truss of straw, which admits the air freely, while defending the entrance. There is the eternal question, if we do not rise above the commonplace: how did the insect acquire so wise an art?
Not one fails in obeying those two laws, the safety of the egg and ready ventilation; not one, not even the next on my list, whose talent opens up a new horizon: I am now speaking of Lacordaire's Gromphas. Let not this repellant name of Gromphas (the old sow) give us a wrong notion of the insect. On the contrary, it is, like the last, an elegant Dung-beetle, dark-bronze, thickset, square-shaped like our Bison Onitis15 and almost as large. It also practises the same industry, at least as regards the general effect of the work.
15 Cf. The Sacred Beetle and Others: chap. xvi.—Translator's Note.
Its burrow branches into a small number of cylindrical cells, forming the homes of as many larvæ. For each of these the provisions consist of a parcel of Cow-dung, about an inch deep. The material is carefully packed and fills the bottom of the cavity, just as a soft paste would do when pressed down in a mould. Until now the work is similar to that of the Bison Onitis; but the resemblance goes no farther and is replaced by profound and curious differences, having no connection with what the Dung-beetles of our own parts show us.
As we know, our sausage-makers, Onites and Geotrupes alike, place the egg at the lower end of their cylinder, in a cell contrived in the very midst of the mass of foodstuffs. Their rival in the pampas adopts a diametrically opposite method: she places the egg above the victuals, at the upper end of the sausage. In order to feed, the grub does not have to work upwards; on the contrary, it works downwards.
More remarkable still: the egg does not lie immediately on top of the provisions; it is installed in a clay chamber with a wall about one-twelfth of an inch in thickness. This wall forms an hermetically-sealed lid, curves into a cup and then rises and bends over to make a vaulted ceiling.
The germ is thus enclosed in a mineral box, having no connection with the provision-store, which is kept strictly shut. The newborn grub must employ the first efforts of its teeth to break the seals, to cut through the clay floor and to make a trap-door which will take it to the underlying cake.