on the ventral side, opposite the dorsal vessel, this is by no means established; and, on the other hand, it is certain that a considerable quantity of the sanguineous fluid finds its way into the cavities of the body (lacunæ), and there bathes the intestines. This statement may perhaps cause you some surprise, for you know, no doubt, that in the higher animals an escape of blood internally, from the regular channels in which it is confined, would lead to serious, if not fatal results; and, moreover, the inquiries are at once suggested, "What becomes of the blood after it has entered the cavities of the body? and how is it that the supply is not exhausted?" An examination of the "dorsal vessel" shows that it is not only furnished with valves that unite its chambers, but also with another set, which are placed at the side of the tube, and communicate with the cavities of the body in such a manner as to admit of the ingress, but not the egress of fluid. The blood then, after having bathed the vital organs of the body, accumulates around the dorsal vessel, into which it is admitted by this second set of valves, and again propelled forwards into the thorax. Moreover, this wonderful force-pump (the dorsal vessel), with its chambers and valves, gives out several fine branching arteries, some of which are also said to terminate in the cavities of the body*. * The circulation of the blood in insects may be observed in some of the smaller Diptera, such as gnats, &c., where the external envelope is semitransparent, more easily than in the Bee. The nervous system of the Bee presents the usual articulate type. It consists of a pair of straight parallel chords of nerve-substance that lie side by side, and run along the whole ventral side of the body, beginning in the head and ending near the termination of the abdomen. Upon these chords are distributed several ganglia or nervous centres (resembling pearls strung upon a couple of threads), from which branches proceed to the various organs and members of the body. First, there is the brain (Pl. VII. fig. 2, a), or, as it is technically called, the cephalic, or supraœsophageal ganglion. This is, strictly speaking, two ganglia fused into one, as the illustration will show, and situated (as the names denote) in the head and above the throat; each half gives out a large lateral nerve, the optic nerve (nervus opticus, Pl. VII. fig. 2, 0), which divides into a bundle of finer nerves, whereof one proceeds to each ocellus or subdivision of the compound eye*. From this ganglion also nerves depart to the simple eyes and feelers (fig. 2, n a). Proceeding backwards, we find another ganglion of considerable size situated below the throat, and connected with the brain by the double chord or commissure referred to this ganglion (the sub- or infra-œsophageal, fig. 2, b) supplies the organs of the mouth and the first pair of feet (2, 2) with nerves. Continuing our course backchords, we arrive at the large * See page 26. wards along the central thoracic ganglion (fig. 2, c), composed of grey nervous matter. In the larval stage of the insect this is not one, but three ganglia, which during the metamorphosis become fused into one large ganglion*, the most considerable, in fact, in the whole body, and from it there proceed nerves to the various members of locomotion (3, 4, 5, 6, 7). Compared with the thoracic ganglion, the remaining five, all situated in the abdomen (d, e, f, g, h), are of very small proportions, and each gives out a pair of fine lateral nerves to the organs enclosed in the respective rings, whilst from the last ganglion, which is larger than the rest, there proceed a number of nerves to the reproductive organs. And now, after this somewhat monotonous account of nerves and ganglia, we arrive at what must indeed be regarded as by far the most interesting portion of the Bee's anatomy, when considered in relation to the history of the insect; we mean the organs of reproduction; for their investigation has not only explained much that was before mysterious in its life-history, but has revealed some of the most remarkable phenomena in animated nature. It has been already stated that a hive consists of three kinds of Bees: the drones or males; the workers or females with reproductive organs but partially developed, and consequently of no use in the multiplication of the species; and the queen or perfect female, the mother of the hive, in whom the reproductive system is complete. We shall now ask you to accom * See account of the metamorphosis, Chapter VI. |