What is happening at the same time with the gummy sloes? Nothing whatever. I wait a month: nothing yet. I wait two, three, four months: nothing, still nothing. Not a grub comes out of my prepared sloes. At last, in December, I decide to see what has been going on inside. I crack the stones whose air-holes I have blocked with gum. Most of them contain a dead maggot, which has dried up while quite young. Some hide a live larva, well developed, but lacking in strength. You can see that the creature has suffered not from want of food, for the kernel is almost entirely consumed, but from another unsatisfied need. Lastly, a small number show me a live grub and an exit-hole made in the regular manner. These lucky ones, immured by the gum perhaps when they were already full-grown, had the strength to perforate the casket; but, finding on top of the wood the hateful varnish, which is the result of my perfidy, they obstinately refused to bore any farther. The gummy barrier stopped them short; and it is not their habit to seek their freedom in another direction. Away from the bare floor, the bottom of the crater, they would infallibly come upon the pulp, which is no less detestable than the gum. In short, of the collection of larvæ subjected to my stratagems, not one has thriven; the sealing with gum has been fatal to them. This result puts an end to my hesitations: the cone set up in the centre of the pit is necessary to the existence of the grub sequestered in the stone. Its tunnel is a ventilating-shaft. Each species certainly possesses its peculiar method of maintaining a connection with the outside world, when the larva lives under conditions in which the renewal of the air would be too difficult or even impossible if no precautions were taken. Generally, a fissure, a corridor, more or less unobstructed and the usual work of the grub, is enough to ventilate the dwelling. Sometimes it is the mother herself who sees to these hygienic requirements; and then the method employed is strikingly ingenious. While on this subject, let us recall the wonderful devices of the Dung-beetles. The Sacred Beetle models her grub’s loaf in the form of a pear; the Spanish Copris [51] shapes it like an egg. It is compact, homogeneous and as air-tight as stucco-work. To breathe in these lodgings would unquestionably be a very difficult thing; but the danger is provided against. Look at the small end of the pear and the top of the ovoid. After ever so little reflection, you will be seized with surprise and admiration.