At first sight, this latter detail hardly deserves attention: is it not right to fill the pot before we put a lid on? The Osmia who owns a medium-sized reed is not at all of this opinion; and other plasterers share her views, as we shall see when we watch the Odynerus building her nest. (A genus of Mason-wasps, the essays on which have not yet been translated into English.--Translator's Note.) Here we have an excellent illustration of one of those latent powers held in reserve for exceptional occasions and suddenly brought into play, although often very far removed from the insect's regular methods. If the reed, without being of inordinate width from the point of view of the cocoon, is nevertheless too spacious to afford the Bee a suitable purchase against the wall at the moment when she is disgorging honey and brushing off her load of pollen; the Osmia altogether changes the order of her work; she sets up the partition first and then does the victualling. All round the inside of the tube she places a ring of mud, which, as the result of her constant visits to the mortar, ends by becoming a complete diaphragm minus an orifice at the side, a sort of round dog-hole, just large enough for the insect to pass through. When the cell is thus marked out and almost wholly closed, the Osmia attends to the storing of her provisions and the laying of her eggs. Steadying herself against the margin of the hole at one time with her fore-legs and at another with her hind-legs, she is able to empty her crop and to brush her abdomen; by pressing against it, she obtains a foothold for her little efforts in these various operations. When the tube was narrow, the outer wall supplied this foothold and the earthen partition was postponed until the heap of provisions was completed and surmounted by the egg; but in the present case the passage is too wide and would leave the insect floundering helplessly in space, so the partition with its serving-hatch takes precedence of the victuals. This method is a little more expensive than the other, first in materials, because of the diameter of the reed, and secondly in time, if only because of the dog-hole, a delicate piece of mortar-work which is too soft at first and cannot be used until it has dried and become harder. Therefore the Osmia, who is sparing of her time and strength, accepts medium-sized reeds only when there are no small ones available. The large tubes she will use only in grave emergencies and I am unable to state exactly what these exceptional circumstances are. Perhaps she decides to make use of those roomy dwellings when the eggs have to be laid at once and there is no other shelter in the neighbourhood. While my cylinder-hives gave me plenty of well-filled reeds of the first and second class, they provided me with but half-a-dozen at most of the third, notwithstanding my precaution to furnish the apparatus with a varied assortment.