British Butterflies. William S. Coleman

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СКАЧАТЬ been pulled apart. We all know how completely it is made whole again, and on examining by what means this result is brought about, we find that it is by the interlacing of a number of small fibres or hairs, just as, on a larger scale, a pair of brushes adhere when pressed face to face; and so in the butterfly's sucker, the two edges that join to form the tube are closely set with minute bristles that, when brought together, interlock so closely as to make an air-tight surface.

      Fig. 9, Plate II., is a transverse section taken near the base of the sucker, the small opening at the top being the food passage, those at the side the air-tubes that supply air for respiration and perhaps assist in suction.

      The tube is probably made with separable parts in order that if its interior should become at any time clogged by grosser particles drawn up with the flower nectar, it may be opened and cleansed by the insect; otherwise, the tube once rendered impassable, the insect would speedily starve, as this narrow channel is the only inlet for the creature's nourishment—its only mouth, in fact, for no butterfly possesses jaws to bite with, or can take any but the liquid food pumped up by suction through this pipe.

      At the end of the proboscis—or, as it is called scientifically, the Haustellum^[3]—there are visible in some butterflies a number of small projections, of the form shown at fig. 10, Plate II., which is a highly magnified figure of the end of the Red Admiral's proboscis. These appendages are generally supposed to be organs of taste, and to aid in the discrimination of food when the pipe is unrolled and thrust down deep into the nectary of a flower.

      The compound eye of a butterfly, wonderful as its structure is, does not greatly differ from that of many other insects, being like them composed of an immense number of little lenses set together to form a hemisphere large in comparison with the insect's head. A portion of one of these eyes forms a pretty and interesting object for the microscope, presenting a honey-comb appearance, the hexagonal lines that mark the division of the lenses being most beautifully geometrical and regular in their arrangement. More than seventeen hundred of these lenses have been counted in a single eye, and each of these is considered to possess the qualities of a complete and independent eye. If this be true, the butterfly may be said to be endowed with at least thirty-four thousand eyes!

      There exist also, as in other insects, two simple eyes, placed on the top of the head, but so buried in down and scales as to be neither visible, nor useful for vision as far as we can perceive; probably the creature finds that his allowance of thirty-four thousand windows to his soul lets in as much light as he requires.

      Every one looking at a butterfly must have remarked its long horns, called antennæ,^[4] which project from above the eyes, like jointed threads, thickening—in some species gradually, in others suddenly—into a club or knob at the extremity; a peculiarity which, it will be remembered, was pointed out at the commencement, as a prominent mark of distinction between butterflies and moths.

      Very graceful appendages are these waving antennæ, and evidently of high importance to their owner; but still, their exact office or function is unknown, notwithstanding that many guesses and experiments have been made with a view of settling that question.

      Investigators have perhaps erred, by assuming at the outset that these antennæ must be organs of some sense that we ourselves possess; whereas, I think that there is much evidence to show that insects are gifted with a certain subtle sense, for which we have no name, and of which we can have as little real idea, as we could have had of the faculty of sight, had all the world been born blind.

      For example; if you breed from the chrysalis a female Kentish Glory Moth, and then immediately take her—in a closed box, mind—out into her native woods, within a short space of time an actual crowd of male "Glories" come and fasten upon, or hover over, the prison-house of the coveted maiden. Without this magic attraction, you might walk in these same woods for a whole day and not see a single specimen, the Kentish Glory being generally reputed a very rare moth; while as many as some 120 males have been thus decoyed to their capture in a few hours, by the charms of a couple of lady "Glories," shut up in a box.

      Now, which of our five senses, I would ask—even if developed into extraordinary acuteness in the insect—would account for such an exhibition of clairvoyance as this?

      May not, then, this undiscovered sense, whatever may be its nature, reside in the antennæ? for it is a remarkable fact, that the very moths, such as the Eggers, the Emperor, the Kentish Glory, &c., which display the above-mentioned phenomenon most signally, have the antennæ in the males amplified with numerous spreading branches, so as to present an unusually large sensitive surface. This seems to point to some connexion between those organs and the faculty of discovering the presence, and even the condition, of one of their own race, with more, perhaps, than a mile of distance, and the sides of a wooden box, intervening between themselves and their object.

      Whilst writing this, the current number of the "Entomologist's Weekly Intelligencer" has arrived, and I there read that Dr. Clemmens, an American naturalist, has been lately experimenting on the antennæ of some large American moths, for the purpose of gaining some information as to their function. The article, though very interesting, is too long for quotation here; but it appears that with the moths in question, a deprivation of the whole, or even part of the antennæ, interferes with, or entirely annihilates the power of flight, so that the creature when thus shorn, but not otherwise injured, if thrown into the air seems to have no idea of using his wings properly, but with a purposeless flutter tumbles headlong to the earth. Still this merely goes to prove that the antennæ are the instruments of some important sense, one of whose uses is to guide the creature's flight; but as many wingless insects have large antennæ, this evidently is not their only function.

      The antennæ are also often styled the "feelers;" but with our present incomplete knowledge of their nature, the former term is preferable, as it does not attempt to define their use as the word "feelers" does.

      Considerable variety of form exists in the clubbed tip of the antennæ in various butterflies, as will be seen by reference to Plate II., where three of the most distinct forms are shown considerably magnified. Fig. 12 is the upper part of the antenna of the High-brown Fritillary (Argynnis Adippe), the end suddenly swelling into a distinct knob. Fig. 13 is that of the Swallow-tail Butterfly (Papilio Machaon), the enlargement here being more gradual; and fig. 14 is that of the Large Skipper Butterfly (Pamphila Sylvanus), distinguished by the curved point that surmounts the club. These differences in the forms of the antennæ are found to be excellent aids in the classification of butterflies, and I shall therefore have occasion to refer to them more minutely in describing the insects in detail.

      The stems of these organs are found to be tubular, and at the point of junction with the head the base is spread out (as shown at fig. 15), forming what engineers call a "flange," to afford sufficient support for the long column above.

      The legs are the last portions of the butterfly framework that require especial notice, on account of a peculiar variation they are subject to in different family groups.

      It may be laid down as an axiom, that all true insects have six legs, in one shape or another; and butterflies, being insects, are obedient to the same universal rule, and duly grow their half-dozen legs; but in certain tribes the front pair, for no apparent reason, are so short and imperfect as to be totally useless for walking purposes, though they may possibly be used as hands for polishing up the proboscis, &c. So the butterfly in this case appears, to a hasty observer, to have only four legs.

      This peculiarity is a constant feature in several natural groups of butterflies, СКАЧАТЬ