This necessary detail I shall endeavour to make as entertaining as I possibly can, by introducing, with the description of the organ, the uses it serves in the economy of the insect. I hope thus to add an interest to it which a merely dry technical and scientific definition would not possess. Structure is always expressive of the habits of the bees, and is as sure a line of separation, or means of combination, as instinct could be were it tangible. Hence the conclusion always follows with a certainty that such-and-such a form is identical with such-and-such habits, and that, in the broad and most distinguishing features of its economy, the genus is essentially the same in every climate. Climate does not act upon these lower forms of animal life, with the modifying influences it exercises upon the mammalia and man. A _Megachile_ is as essentially a _Megachile_ in all its characteristics in Arctic America, the Brazils, tropical Africa, Northern China, and Van Diemen’s Land, as in these islands, and _Apis_ is, wherever it occurs, as truly an _Apis_. Therefore the habits, in whatever country the genus may be found, can thus be as surely affirmed of all its species, from the knowledge we have of those at home, as if observation had industriously tracked them. Therefore, the technicalities of structure once learnt, they become permanently and widely useful. The body of the bee consists of a head, thorax, and abdomen, which, although to the casual observer, seemingly not separated from each other, are, upon closer inspection, more or less distinctly disconnected. The three parts are merely united by a very short and slight tubular cylinder. This is sometimes so much reduced as to be only a perforation of the parts combined by a ligament, and through which aperture a requisite channel is formed for the passage of the ganglion or nervous chord, which extends from one portion of the body to the other, giving off laterally, in its progress from the sensorium in the head onwards, the filaments required by the organs of sensation and motion, as well as all which control the other functions of the body of the insect. [Illustration: Fig. 4.—Body of the bee. _a_, head and antennæ; _b_, vertex and ocelli; _c_, genæ, or cheeks; _d_, prothorax; _e_, mesothorax; _f_, squamulæ; _g_, insertion of the wings; _h_, scutellum; _i_, post-scutellum; _k_, metathorax; _l_, abdomen.] These apertures form also the necessary medium of connection between the several viscera, whereby the food and other sustaining juices are conveyed from the mouth through the œsophagus to the various parts of the body.