With the tools which it possesses, the insect could obtain other forms of a less delicate curve than its pear-shaped piece of work. It could, for instance, make a rough cylinder, the sausage customary among the Geotrupes; or, simplifying the work to the utmost, it could leave the lump without any definite form, just as it happened to find it. Things would proceed all the faster and would leave more time for playing in the sun. But no: the Sacred Beetle never chooses any shape but the sphere, though it necessitates such scrupulous accuracy; she acts as though she knew the laws of evaporation and geometry from beginning to end. It remains for us to examine the neck of the pear. What can be its object, its use? The reply forces itself upon us irresistibly. This neck contains the egg, in the hatching-chamber. Now every germ, whether of plant or animal, needs air, the primary stimulus of life. To admit that vivifying combustible, the shell of a bird’s egg is riddled with an endless number of pores. The pear of the Sacred Beetle may be compared with the egg of the Hen. Its shell is the rind, hardened by pressure, to avoid untimely desiccation; its nutritive mass, its meat, its yolk is the soft ball sheltered under the rind; its air-chamber is the terminal space, the cavity in the neck, where the air envelops the germ on every side. Where would that germ be better off, for breathing, than in its hatching-chamber projecting into the atmosphere and giving free play to the passage of gases through its thin and easily permeable wall? In the centre of the mass, on the other hand, aeration is not so easy. The hardened rind does not possess pores like an egg-shell’s; and the central kernel is formed of compact matter. The air enters it nevertheless, for presently the grub will be able to live in it: the grub, a robust organism which does not need the same tender flutter of life as the sensitive germ. Where the adolescent larva thrives, the egg would die of suffocation. Here is a proof of it. I take a small, wide-necked phial and fill it with Sheep-dung, the fare required in this case. I push in a bit of stick and obtain a shaft which shall represent the hatching-chamber. Down this shaft I place an egg carefully moved from its cell. I close the orifice and cover up everything with a thickly-heaped layer of the same material. Here, in all excepting the shape, we have an artificial reproduction of the Sacred Beetle’s pellet; only, in this instance, the egg is in the centre of the mass, the place which over-hasty considerations made us but now believe the most suitable. Well, the point which we selected is fatal to life. The egg dies there. What has it lacked? Apparently, proper aeration.