Making ample allowance for anatomy, a precious aid, what do we know of animals? Next to nothing. Instead of inflating cabbalistic bladders with this nothing, let us collect well-observed facts, however humble. From a sheaf of such facts a clear, calm light may shine forth one day, a light far preferable to the fireworks of theories which dazzle us for a moment only to leave us in blacker darkness. Here is this little detail. By some accident an egg has fallen from the blue globe, its regular lodging, into the axilla of a leaf half-way up the stem. We can even admit, if we choose, that the mother, either by inadvertence or by intention, laid it at this point herself. What will become of the egg under such conditions, so far removed from the rules? What I have before my eyes tell us. The grub, faithful to custom, has not failed to broach the stem of the thistle, which allows the nourishing moisture to ooze from the wound. As a defence it has built itself a pitcher similar in shape and size to that which it would have obtained in the thistle-head. This novel edifice lacks only one thing: the roof of dead florets bristling on the customary hut. The builder has contrived to do very well without its floral pantiles. It has made use of the base of the leaf, one lobe of which is involved, as a support, in the wall of the cell; and from both leaf and stalk it has taken the ligneous particles which it had to imbed in the cement. In short, except that it is bare instead of surrounded with a palisade, the fabric adhering to the stalk does not differ from that hidden beneath the withered florets of the thistle-head. People set great store by environment as a modifying agent. Well, here we see this famous environment at work. An insect is placed as much out of its element as it can be, but without leaving the food-plant, which would inevitably be the end of it. Instead of a ball of close-packed flowers it has for its workshop the open axilla of a leaf; instead of hairs—a soft fleece easily shorn off—it has for its materials the fierce teeth of the thistle. And these profound changes leave the builder’s talents unperturbed; the house is built according to the usual plans. I agree that I have not allowed for the influence of the centuries. But what would this influence bring about? It is not very clear. The Weevil born in an unusual place retains no trace of the accident that has happened. I extract the adult from his exceptional cell. He does not differ, even in size, a not very important characteristic, from the Larini born in the regular cell. He has thriven on the axilla of the leaf as he would have done on the thistle-head. Let us admit that the accident is repeated, that it even becomes a normal condition; let us suppose that the mother decides to abandon her blue balls and to confide her eggs to the axillæ of the leaves indefinitely. What will this change bring about? The answer is obvious.