In April I make a copious collection of cocoons. Of these I place ten or twelve at the bottom of test-tubes of different diameters and, last of all, I fill the apparatus with sandy soil, sifted and very slightly moistened. The contents are pressed down, but in moderation, for fear of injuring the cocoons below. When the month of August comes, the column of earth, damp at the outset, has set so firmly, thanks to evaporation, that, when I reverse the test-tube, nothing trickles out. On the other hand, some cocoons have been kept naked under a metallic cover. These will teach me what the buried cocoons would not be able to show. They furnish me, in fact, with records of the greatest interest. On issuing from the cocoon, the Pine Bombyx has her finery bundled up and presents the appearance of a cylinder with rounded ends. The wings, the principal obstacle to underground labour, are pressed against the breast like narrow scarves; the antennæ, another serious embarrassment, have not yet unfolded their plumes and are turned back along the Moth’s sides. The hair, which later forms a dense fleece, is laid flat, pointing backwards. The legs alone are free, fairly active and endowed with a certain vigour. Thanks to this arrangement, which does away with all awkward projections, the ascent through the soil is made possible. True, every Moth, at the moment of quitting her shell, is this sort of swathed mummy; but the Pine Bombyx has in addition an exceptional aptitude rendered necessary by the fact that she hatches under the ground. While the others, once out of the cocoon, hasten to spread their wings and are powerless to defer their development, she, by virtue of an indispensable privilege, remains in her compact and wrapped-up condition as long as circumstances demand it. Under my bell-glasses I see some who, though born upon the surface, for twenty-four hours drag themselves over the sand or cling to the pine-branches, before untying their sashes and unfurling them as wings. This delay is evidently essential. To ascend from beneath the earth and reach the open air, the Moth has to bore a long tunnel, which requires time. She will take good care not to spread her finery before emerging, for it would hamper her and would itself be rumpled and badly creased. Therefore the cylindrical mummy persists until the deliverance is effected; and, if liberty happen to be acquired before the appointed moment, the final evolution does not take place until after a lapse of time in conformity with usage. We are acquainted with the equipment for emergence, the tight-fitting jerkin indispensable in a narrow gallery. Now, where is the boring-tool? The legs, though free, would here be insufficient: they would scrape the earth laterally, enlarging the diameter of the shaft, but could not prolong the exit vertically, above the insect’s head. This tool must be in front.