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.
Fig. 27.—Head of Bee, With Antennæ.
a. Antennæ.b. Compound eyes. c. Jaws.
d. Maxillae. e. Labial palpi. f. Ligula,
or tongue. g. Stemmata.
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."