The argument is erroneous: instinct developed by degrees is flagrantly impossible in this case. The art of preparing the larva’s provisions allows of none but masters and suffers no apprentices; the Wasp must excel in it from the outset or leave the thing alone. Two conditions, in fact, are absolutely essential: that the insect should be able to drag home and store a quarry which greatly surpasses it in size and strength; and that the newly-hatched grub should be able to gnaw peacefully, in its narrow cell, a live and comparatively enormous prey. The suppression of all movements in the victim is the only means of realizing these conditions; and this suppression, to be complete, requires sundry dagger-thrusts, one in each motor centre. If the paralysis and the torpor be not sufficient, the Grey Worm will defy the efforts of the huntress, will struggle desperately on the road and will not reach the journey’s end; if the immobility be not complete, the egg, fixed at a given spot on the worm, will perish under the contortions of the giant. There is no via media, no half-success. Either the caterpillar is treated according to rule and the Wasp’s family is perpetuated; or else the victim is only partially paralysed and the Wasp’s offspring dies in the egg. Yielding to the inexorable logic of things, we will therefore admit that the first Hairy Ammophila, after capturing a Grey Worm to feed her larva, operated on the patient by the exact method in use to-day. She seized the creature by the skin of the neck, stabbed it underneath, opposite each of the nerve-centres and, if the monster threatened further resistance, munched its brain. It must have happened like this; for, once more, an unskilled murderess, doing her work in a perfunctory and haphazard fashion, would leave no successor, since the rearing of the egg would become impossible. Save for the perfection of her surgical powers, the slayer of fat caterpillars would die out in the first generation. Again I hear you say: ‘The Hairy Ammophila, before hunting the Grey Worm, may have picked out feebler caterpillars and heaped up several in one cell, until they represented the same bulk of provender as the big prey of to-day. With puny game, a few thrusts of the needle, perhaps one, would be enough. Gradually, large-sized prey came to be preferred, as reducing the number of hunting expeditions. Then, as successive generations went after bigger game, the dagger-strokes were multiplied, in proportion to the victim’s power of resistance; and, by degrees, the elementary instinct of the outset became the highly-developed instinct of our time.’