Is there not at least a measuring adapted to each sex? Again, not so; for in the first series, where the females are housed, instead of the interval of 11 millimetres, which occurs at the beginning and the end, we find, in the middle of the series, an interval of 16 millimetres, while in the second series, reserved for the males, instead of the interval of 7 millimetres at the beginning and the end, we have an interval of 5 millimetres in the middle. It is the same with the other series, each of which shows a striking discrepancy in its figures. If the Osmia really studied the dimensions of her chambers and measured them with the compasses of her body, how could she, with her delicate mechanism, fail to notice mistakes of 5 millimetres, almost half her own length? Besides, all idea of geometry vanishes if we consider the work in a tube of moderate width. Here, the Osmia does not fix the front partition in advance; she does not even lay its foundation. Without any boundary-pad, with no guiding mark for the capacity of the cell, she busies herself straightway with the provisioning. When the heap of Bee-bread is judged sufficient, that is, I imagine, when her tired body tells her that she has done enough harvesting, she closes up the chamber. In this case, there is no measuring; and yet the capacity of the cell and the quantity of the victuals fulfil the regular requirements of one or the other sex. Then what does the Osmia do when she repeatedly stops to touch the front partition with her forehead and the back partition, the one in the course of building, with the tip of her abdomen? I have no idea what she does or what she has in view. I leave the interpretation of this performance to others, more venturesome than I. Plenty of theories are based on equally shaky foundations. Blow on them and they sink into the quagmire of oblivion. The laying is finished, or perhaps the cylinder is full. A final partition closes the last cell. A rampart is now built, at the orifice of the tube itself, to forbid the ill-disposed all access to the home. This is a thick plug, a massy work of fortification, whereon the Osmia spends enough mortar to partition off any number of cells. A whole day is not too long for making this barricade, especially in view of the minute finishing-touches, when the Osmia fills up with putty every chink through which the least atom could slip. The mason completing a wall smooths his plaster and brings it to a fine surface while it is still wet; the Osmia does the same, or almost. With little taps of the mandibles and a continual shaking of her head, a sign of her zest for the work, she smooths and polishes the surface of the lid for hours at a time. After such pains, what foe could visit the dwelling?