I seem to catch a glimpse of the reason for this long watch. The pill-rollers, whether Scarabs or Gymnopleuri, never have more than a single pear, a single ovoid in their burrows. The mass of foodstuff, which at times is rolled from a great distance, is necessarily limited by the insect’s own limitations of strength. It is enough for one larva, but not enough for two. An exception must be made with respect to the Broad-necked Scarab, who brings up her family very frugally and divides her rolling booty into two modest portions. The others are obliged to dig a special burrow for each egg. When everything is in order in the new establishment—and this does not take long—they leave the underground vault and go off somewhere else, wherever chance may lead them, to begin their pill-rolling, excavating and egg-laying once more. With these nomadic habits, any prolonged supervision on the mother’s part becomes impossible. The Scarab suffers by it. Her pear, which is magnificently regular at the outset, soon shows cracks and becomes scaly and swollen. Various cryptogams invade it and undermine it; the material expands and the resultant splitting causes the pear to lose its shape. We have seen how the grub combats these troubles. The Copris has other ways. She does not roll her stores from a distance; she warehouses them on the spot, bit by bit, which enables her to accumulate in a single burrow enough to satisfy all her brood. As there is no need for further expeditions, the mother stays and keeps watch. Under her never-failing vigilance, the pill does not crack, for any crevice is stopped up as soon as it appears; nor does it become covered with parasitic vegetation, for nothing can grow on a soil that is constantly being raked. The two or three dozen ovoids which I have before my eyes all bear witness to the mother’s watchfulness: not one of them is split or cracked or infested with tiny fungi. In all of them the surface is irreproachable. But, if I take them away from the mother to put them into a bottle or tin, they suffer the same fate as the Sacred Beetle’s pears: in the absence of supervision, destruction more or less complete overtakes them. Two examples will be instructive to us here. I take from a mother two or three pills and place them in a tin, which prevents them from getting dry. Before a week has passed, they are covered with a fungous vegetation. More or less everything grows in this fertile soil; the lesser fungi delight in it. To-day it is an infinitesimal crystalline plant swollen into a bobbin-shape, bristling with short, dew-beaded hairs and ending in a little round head as black as jet. I have not the leisure to consult books and microscope and give a name to the tiny apparition which attracts my attention for the first time. This botanical detail is of little importance: all that we need know is that the dark green of the pills has disappeared under the thick white crystalline growth stippled with black specks.