Before proceeding to detail the most important facts connected with the internal economy of the hive, it will be desirable to describe with some minuteness the physiology and anatomy of the inhabitants, so that it may be more easy to understand the means by which various processes are accomplished, and the most important events of the community are brought about. Much that has been hitherto said will become more readily comprehended by attention to the structure of the various organs we are now about to describe.

It will hardly be necessary to enter into a more minute account, than we have already given, of the egg, the larva, and the pupa. We shall, therefore, confine ourselves to detailing the most interesting points in the physiology of the perfect insect.

It has been noted, in an earlier chapter, that the members of this division of the animal kingdom are characterised by having three very distinct segments in their bodies the head, the thorax, and the abdomen. As the nature and arrangement of the nervous system forms one of the soundest bases of classification in the highest of the three kingdoms in nature, we shall first direct attention, in each case, to this all-important matter of detail.

The general arrangement of the nerve-matter in the sub-kingdom Articulata, to which all true insects belong, is that of a double cord, with knot-like protuberances, called ganglia, at more or less regular intervals. The two filaments are in some cases close together: in others, quite distinct; while the larger nerve-masses—the previously mentioned ganglia—also vary in juxtaposition, according to the greater or less importance of the functions they regulate. In the illustration of the larva of Sphinx ligustri (the privet hawk-moth) (Fig. 22), the nervous cord is nearly uniform throughout its length, though at its upper portion a separation takes place into three loops. The ganglia also occur at almost equal distances. A very similar disposition of the nerve-structure is seen in the larval condition of the bee; but we may note the absence of loops, the larger development of the cephalic masses, without the separation of their filaments to inclose the gullet together with a more plainly-defined distance between the cords which run parallel through the rest of the body.

In the perfect insect we observe some decided modifications to have taken place. The head portions have grown proportionally larger, and show a loop for the passage of the œsophagus, while two large ganglia in the thorax indicate the seat of impressions and impulses connected with the organs of motion—wings and legs—which had no existence in the larval condition. As the functions of the abdominal region, viz., those of digestion and circulation chiefly, remain much the same in the different states through which the individual passes after the hatching of the egg, we find, as we might expect, little change in the nervous system of the posterior segment of the body.

From each nerve-mass will be observed filaments branching on either side to the outer edges of the body. By means of these communication is kept up between all parts of the frame. Sensations are received and conveyed to the sensorial organs, and return-stimuli are sent to the organs whose movements depend for regulation on the different ganglia. This branching of the nerve-fibre is directly proportional to the variety and force of the several functions subserved by the various structures to which they proceed.

The Head.—We will now describe in some detail the structure and functions of the highly-important organs contained in the anterior segment, or head. And first in order let us take the

Eyes.—On either side of the head may be observed an oval lobe, convexly rounded and immovable, brown in colour, covered with a horny tunicle, and exhibiting to the unassisted eye a vast number of distinct points. These points, under a high-power magnifying-glass, are seen to be facets, hexagonal in shape, so as to occupy all available space, without interstices, and each connected with a minute tube and a thread of nerve-matter leading to the cephalic ganglia or brain. These compound eyes, as they are called, are common to most true insects. They may be easily seen in flies, bluebottles, moths, butterflies, &c. The numbers of the facets vary greatly in different families of the Articulata. In the common house-fly there are, it is stated, about 4,000; in the white cabbage-butterfly, 17,000; in the dragon-fly, 24,000. It has been computed that in each compound eye of the bee there are about 3,500 of them.

Behind the horny covering, or cornea, which consists of two plano-convex lenses, is a layer of dark pigment, which gives the characteristic colour to these eyes. This is pointed like the neck of a vase, and serves the purpose of the iris in the higher animals. This is traversed by a minute aperture or pupil, through which the rays pass by a longer conical lens to the optic nerve. A vertical section shows that each ocellus (or little eye) is the frustum of a pyramid, the large end or base of which is bounded by the cornea, while the other and pointed end terminates against an expansion of the optic nerve. The eminent physiologist, Dr. W. B. Carpenter, says, in describing the minute structure of these organs: "The interior of this pyramid is occupied by a transparent substance, which represents the vitreous humour (of the eyes of vertebrates), and the pyramids are separated from each other by a layer of dark pigment, which completely incloses them, save at the pupillary apertures, and also at a corresponding set of apertures at their smaller ends, where the pigment is perforated by the fibres of the optic nerve, of which one proceeds to each separate eye.

"Each facet, or 'corneule' of the common cornea, is convex on both its surfaces, and thus acts as a lens, the focus of which has been ascertained, by experiment, to be equivalent to the length of the transparent pyramid behind it; so that the image produced by the lens will fall upon the extremity of the filament of the optic nerve, which passes to its truncated end. The rays which have passed through the several 'corneules' are prevented from mixing with each other by means of the layer of black pigment which surrounds each cone; and thus, no rays, except those which correspond with the axis of the cone, can reach the fibres of the optic nerve. Hence it is evident that each separate eye must have an extremely limited range of vision, being adapted to receive but a very small pencil of rays proceeding from a single point in any object; and as these eyes are immovable, they would afford but very imperfect information of the position of surrounding objects, were it not for their enormous multiplication, by which a separate eye, so to speak, is provided for each point to be viewed. No two of these, save those upon the opposite sides of the head, which are directed exactly forwards, can form an image of the same point at the same time; but the combined action of all of them may give to the insect, it may be imagined, as distinct a picture as that we obtain by a very different organisation." We venture to suggest that another reason for the vast multiplication of the numbers of "ocelli" is to enable the insects to see in what would be to us darkness. Nearly all the operations carried on in the interior of the hives are done, during the day-time, in very dim light; and in the night-time, when work is by no means intermitted, there would, to our eyes, be absolute darkness. To the bees, however, the scanty rays received by so many sensitive points may be sufficient to enable them to see with considerable clearness. If the simple enlargement of a single pupil, such as takes place in us on emerging from a strong into a dim light, makes so great a difference in our power of vision a fact with which we are all familiar on going from a well-lighted room into what seems for the first few seconds complete darkness we may well believe that the permanent means of entry into the sensorium of an immense number of separate rays may give greatly enlarged powers of seeing scantily illuminated objects.

Still, an opposite view is held by many naturalists, for it seems very doubtful whether there is any power in the bee of focusing these eyes, so as to adapt their range to different distances. The probability is that no such faculty of adjustment exists in them. We should expect this from the structure of the visual apparatus. Yet it seems possible that the compound eyes act as telescopes, and serve for great range of vision, but not for near objects. For, while bees dart homewards from far-off fields with the directness of an arrow, they will frequently fly against persons or things in the direct line of their course, without apparently having seen them at a little distance off. Moreover, when they have alighted within an inch or two of the entrance to their hives, they often fail to perceive its position, and constantly wander to one side or the other, searching for their way in. We might conclude, therefore, that these compound eyes confer distinctness of vision afar, and possibly ability to use up scanty light, rather than any great discernment of objects near at hand.

In addition to these "facetted" eyes, bees have, on the top of the head, three simple ones, called by some writers "coronets," by others "stemmata." Their position and arrangement are shown at g in Fig. 27, p. 98. The focal length of their lens is said to be short, and they are supplied with numerous filaments from the optic ganglia. The special purpose of these simple organs is not well ascertained. If their focal length is short, this would seem to imply that their range of vision is also very limited. But it is very possible they may possess a focusing power, which would adapt them for seeing at all distances. Réaumur thinks they may, with their hemispherical lens, act as microscopes. This point needs further investigation, as the subject of the uses of these two kinds of visual apparatus is, at present, very far from satisfactorily elucidated. One remarkable fact relating to the "stemmata" must be mentioned. It is that, if they be covered with a little opaque paint, the bee, on being let go, will fly continually upwards. Dr. W. B. Carpenter considers this curious fact due to automatic movements initiated by the ganglia connected with flight, uncontrolled by the visual impressions which the simple eyes convey in their natural condition. Neither kind of eye has a lid, but both are protected from dust by numerous small hairs growing round them, and in the points of junction of the facets.

How far the eyes of bees enable them to distinguish colours is still a moot point. On a priori grounds we should expect that one very definite object in the hues of flowers is to attract the notice of insects, just as we have strong reason to believe that odours exhaled in the vegetable world serve this purpose. Sir John Lubbock has detailed a series of experiments on this point, the following summary of which is abstracted from his work on Ants, Bees, and Wasps. He says, p. 304: "In recording the results I marked down successively the order in which the bee went to the different-coloured glasses (on which honey was placed). For instance, in the first journey from the nest, as recorded below, the bee lit first on the blue, which accordingly I marked I; when the blue was removed, she flew about a little, and then lit on the white; when the white was removed she settled on the green; and so on successively on the orange, yellow, plain, and red. I repeated the experiment a hundred times, using two different hives one in Kent, and one in Middlesex and spreading the observations over some time, so as to experiment with different bees, and under varied circumstances. Adding the numbers together, it, of course, follows that the greater the preference shown for each colour, the lower will be the number standing against it.

"The following table gives the first day's observations in extenso:—

"In the next series of experiments the bees had been trained for three weeks to come to a particular spot on a large lawn, by placing from time to time honey on a piece of plain glass. This naturally gave the plain glass an advantage; nevertheless, as will be seen, the blue still retained its pre-eminence. It seems hardly necessary to give the observations in detail. The following table shows the general result:—

"The precautions taken seem to me to have placed the colours on an equal footing; while the number of experiments appears sufficient to give a fair average." As this table differs in form from the other, it may be as well to explain the first line of figures in illustration of the whole. The first series consisted of eleven experiments. The preferences were noted as before, and when the numbers indicating these were added up, the results were that twenty-six represented the total for the blue glass, thirty-nine for the green, fifty-one for the orange, sixty-five for the plain glass, fifty-five for the red, thirty-five for the white, and thirty-seven for the yellow the blue being again manifestly the most attractive colour to the bees. Some practical bee-keepers consider the question by no means settled. The field is doubtless open for further exploration.

The Antennæ. In the front part of the head are two organs, which appear to supplement, in some remarkable way, probably by touch-sensations, the power of vision, and also to possess other capabilities constituting a sense to which we have nothing strictly analogous. These organs are called antennæ. They spring from origins near together, at equal distances from the medial and anterior point of the head, and are connected, by distinct and somewhat large filaments, with the nerve matter forming the cephalic ganglia. Externally they consist, first, of one segment nearest the head, much longer than the rest. This part is called the scape. Then, forming a sort of elbow with it, is the flagellum, consisting of eleven joints in queens and workers, and of twelve in the drones. These segments are tubular, and so attached to each other as to give the greatest possible freedom of motion. Their extremities are wonderfully sensitive, and it is probable that there is a very delicate power of feeling in each of the joints. For the cleansing of these organs, special provision is made in the construction of the fourth and fifth joints of the most forward pair of legs. At the anterior part of the tibia, or fourth joint, is a spur, within, and at the base of, which is a small angular projection, called the velum or sail. At the base of the next joint, and opposite the play of this velum, is found a deep notch. From the fact of its being fringed with hairs, this is called the curry-comb. Upon this notch the velum can act at the will of the insect, and, when shut over one another, they form a circular orifice, just large enough to take the antennæ. When the latter organ needs cleansing, it is laid within the notch: the velum is pressed over it, and being drawn through the round space, dust and other soilures are removed from its surface. So particular are the bees about keeping their antennæ thoroughly clean, that they may often be observed continuing this operation of drawing them through the curry-comb till perfectly satisfied with their condition. Doubtless, the delicate nature of the impressions to which these organs are susceptible, supplies the reason for the care taken in freeing them from all extraneous substances.

The uses served by the antennæ are various and very remarkable. Their first function seems to be to supplement vision. Endowed with exceeding flexibility, they are kept by the insects in constant motion; and when their eyes fail to guide them to particular spots, such as the entrance to the hive, or as to the nature of objects with which they come into contact, the antennæ appear to supply the necessary information. There is little doubt that these "horns" or "feelers," as they are commonly called, are sensitive, also, to impressions from objects at some distance. Vibrations of the air too feeble to affect our organs affect them. It may even be that other qualities of the atmosphere are apprehended by them. The shape of the cells; the suitability of these for brood of various kinds, for honey or for bee-bread, is ascertained by the antennæ. Every want and every duty is recognised by them; the presence or absence of the queen is discovered by their use, and intelligence is conveyed from one individual to another by means of them.

Of these facts, Huber has given the following striking evidence. He divided a stock hive into two parts by metal network, sufficiently fine to prevent the passage of the bees, but with meshes wide enough to allow the antennæ to be passed through. At first, by a pair of such gratings at a little distance apart, he separated the two portions, so that no communication whatever could take place between them. Very soon that half from which the queen was excluded showed signs of commotion and distress, and even began to prepare queen-cells, to supply themselves with a new sovereign; but when, by the removal of one grating, Huber allowed the feelers to be used to convey intelligence between the bees on opposite sides of the remaining division, he saw the insects by hundreds making inquiries as to what had happened. Then the queen was observed on the grating, and the bees being assured, by crossing antennæ with her, that their mother was still in the hive, though shut off from free access to one set of her subjects, they all quieted down, left off making the royal cells, and resumed their various avocations.

Huber tried the further experiment of depriving two queens of their antennæ, and introducing both into the same hive. The population did not seem able to recognise their own sovereign from the stranger, and both were let alone; but, directly he put in a third queen, unmutilated in these organs, the workers fell upon her, and slaughtered her.

The antennæless queens lost all purpose, laid eggs at random, and wandered about the hives as if they had "lost their heads."

Another very curious fact is, that if a worker is deprived of her feelers, and then allowed to fly, she becomes incapable of recognising her hive, even when near to it, and is hopelessly lost as to her whereabouts. From this circumstance we are inclined to conclude that the antennæ are possessed of sensibilities to which we have nothing strictly analogous—that, in fact, there resides in them a sense, or senses, with which mankind is not endowed, one of which we are disposed to call the "homing-sense."

Numerous observations show that by the antennæ, also, distinct information can be given. We have ourselves tried the following experiment in confirmation of this point. Having placed near the entrance of a hive a dead humble-bee, we first noticed one of the sentinels rush to the body, and with her feelers investigate its nature. Finding it was a lifeless creature, and one, therefore, simply to be got rid of, she began to tug at it, to move it towards the edge of the floor-board. At once discovering that the weight was too great for her strength, she went to the entrance, and meeting a friend, by crossing their feelers, the one was made aware of the difficulty of the other. The second then went to the aid of the first; but, as the body was too great a burden for their united efforts, the new-comer gave up her attempts to move it, as if the duty did not concern her much. The first bee, however, would not be baffled till she had fetched several other individuals, one at a time, to the work in hand. But, at length, as she could get no combined action, and as no two were sufficiently strong to haul away the large carcase of their distant relative, she gave up the task in despair, and retired to the hive in apparent disgust.

On a moonlight night the sentries may be observed marching eagerly about the entrances of their abodes, and vigorously moving their antennæ, to ascertain whether moths, or other unwelcome intruders, are trying to get inside the hives. The presence of an enemy being detected, he is soon chased away.

By some naturalists the feelers have been thought to afford the capacity of smell. It is, however, more probable that this sense resides in the mouth itself, or in its immediate neighbourhood.

Whether or not bees appreciate sound, is another moot point. It is, indeed, doubted by many observers whether hearing is possessed at all by insects. Sir John Lubbock records a series of experiments which he conducted on this point, to which we shall make reference a little later on. Those writers, who credit bees with the ability to distinguish sound waves, incline to the belief that the power resides in the antennas. As modern science has shown that all our physical impressions are modifications of vibration, variously interpreted, according to the means by which they are conveyed to the sensorium, we may readily imagine that more than one faculty may reside in these jointed organs of which we have been speaking, and that each separate part may possibly have its own specific function; while, by combined action, such differences may be made as are analogous to chords, and harmonies, or discords in music, as compared with the striking of single notes.

We have dwelt at considerable length on the subject of the antennæ, not simply because what is known of them is so remarkable, but because we wish to draw attention to the fact that there is here a most interesting field for further investigation. Much remains to be done to clear up the mysteries still unsolved, and to harmonise the various observations already made respecting the nature and properties of these organs, which, not only in bees, but in many other families of insects, play such an important part in their life-history.

The Mouth.—Passing next to the mouth, we find a somewhat complex structure; for it consists of many parts, each of which has its ascertained function. We find first, the labrum, or upper lip; the epipharynx, or valve closing the aperture of the gullet; the pharynx, or gullet, forming the true mouth, as well as the entrance to the œsophagus, or food-pipe; the hypopharynx, lying just below the gullet; the labium, or lower lip; and the proboscis, or true tongue. These are all single parts; but there are also pairs of mandibles, or upper jaws, and maxillæ, or lower jaws, besides palpi—certain jointed, sensiferous organs, whose functions are not well understood, but which are possibly connected with the sensation of taste.

The labrum, or upper lip, has a vertical motion, and when not in use falls over the organs beneath it; while it is covered, in its turn, by the mandibles, which are jointed on to the cheeks, and act laterally.

The pharynx is a cavity lying beneath the epipharynx, and can be closed by the latter, over which the two previously described parts lap, so that the entrance to the œsophagus is trebly protected.

The labium, or lower lip, is capable of being pushed forward and retracted, and lies, when not in use, within the under cavity of the head.

On either side are the maxillæ, or so-called jaws, which form the under sheath of the rest of the lingual structures when in repose.

The true tongue is attached to the middle point of the lower lip, having the labial palpi at its sides. It is much elongated when thrust out in use. While at rest, the anterior part folds back upon the posterior portion, when it is covered by the maxillæ, which seem then like a part of the tongue itself. The back is much larger than the front. The whole is flattened, when not sipping liquid. It is then much broader than its thickness, but its edges are rounded. It narrows from its base to its extremity, at which there is a slight inflation, which seems to have a perforation in its centre, and is surrounded by hairs. The tongue has also a large number of cartilaginous rings, each bordered with minute hairs, which appear to be the means used for sweeping up the last remains of any fluid which has been almost exhausted. The act of imbibition is performed, not so much by suction, as by lapping. Its motions being free in all directions, it can easily draw liquid into the mouth on all sides. We notice, however, that when the supply of food being taken is very considerable, the segments of the abdomen have a vibratory motion, or, rather, are alternately lengthened and shortened, as if fluid were being pumped into the body. It is, therefore, possible that, under some circumstances, suction as well as lapping may go on. Still, it is remarkable that a bee does not insert the tip of its proboscis into a drop of honey or other saccharine material, as it would do if it intended to draw liquid through a tube. It much rather uses the middle of the upper surface of the tongue, curving round the point as if not to employ it. If, however, the honey or syrup be very thick, the fore-part of the tongue is thrust into it, possibly to dilute the liquid with saliva, and thus to render it fit for lapping. In all cases the insect tries to load the upper surface, whence the fluid passes backward under the sheaths to the gullet; and we see no reason to believe that the proboscis constitutes a tube for imbibition. A further confirmation of this conclusion is given by Shuckard, who says, "By pressing towards its origin, I have detected the liquid which gave it its extension; but all my pressing would never make the liquid pass through the extremity, although the pressure has sometimes made it almost rend the membranes to give it an opening to escape by."

A further use of the tongue is for shaping the pliant wax in comb-building; and it appears to be employed much as a trowel is by a bricklayer, or, perhaps, we should rather say, like a finger by a moulder of plaster of Paris.

As we have mentioned, the jaws open vertically; but the mandibles and maxillæ work horizontally. They are thus enabled to seize and tightly hold any object they can grasp. The mandibles of the drone and the queen have two notches or teeth. Those of workers are not thus furnished, probably because, for shaping and smoothing the cells, an unbroken edge is much more convenient than a notched one. These organs are, however, very strong, and enable their possessor to grasp enemies, drones or queens; to nibble hard kinds of food; to break away pieces of damaged comb; and to mould wax for building purposes. In the last of these operations they are, doubtless, aided by the shear-like maxillæ.