Hitherto we have been looking at these scales as the component parts of a picture, like the tesseræ of mosaic work; but they are no less interesting as individual objects, when viewed microscopically. To do this, delicately rub off a little of the dust or scales with the finger; then take a slip of glass, and pressing the finger with the adhering dust upon it, the latter will come off and remain on the glass, which is then to be placed under the microscope. These scales may be treated either as opaque or transparent objects, and in both conditions display exceeding beauty, some of these single atoms showing, by aid of the microscope, as
much complexity of structure as the whole wing does to the unassisted vision.
A few of the highly varied forms they present are shown on [Plate II]. Figs. 23 to 38 are selected from among the commoner forms, as seen by a comparatively low power. The small stalk-like appendage is the part by which the scale is affixed to the wing: it may be called the root. Figs. 17, 18, 19, 20, 21, show some very remarkable forms, which are, so far as has been ascertained, peculiar to butterflies of the male sex, though the use or reason of this masculine badge, only visible to highly magnifying optics, is neither known nor probably to be known at present; but singularly beautiful and curious they are to look at. The little balls at the end of threads are the root portion, and fit into cup-like sockets, placed here and there among the ordinary scales. The surface of these scales is beautifully ribbed and cross-ribbed, and at the upper end is a plume-like tuft of delicate filaments. The curious scale aptly called, from its shape, the Battledore scale, and shown at fig. 22, also belongs to the male of various butterflies, especially those pretty little ones known as the "Blues." Its surface is most curiously ornamented with rows of bead-like prominences.
Probably one would imagine that in such wee specks as are these scales, one single layer of substance would suffice for their whole thickness (if we can talk of thickness, with objects almost immeasurable in their thinness). But such is not the case, for when scales have
been injured by rubbing we now and then find a part with the sculptured surfaces torn off on each side, showing a plain central layer, so that at least three layers—two ornamented and one plain—go to form a filmy body, only a small fraction of the thickness of paper.
But there are other portions of a butterfly to claim our interest besides its wondrous wings.
On the creature's head are grouped together some most beautiful and important organs. The most peculiar of these is the long spiral "sucker," which extracts the honied food from the blossoms to which its wings so gracefully waft it. This organ is shown, slightly magnified, at fig. 8, [Plate II]., and a most delicate piece of animal mechanism it is. Any human workman would, to a certainty, be not only puzzled, but thoroughly beaten, in an attempt to construct a tube little thicker than a horse-hair, yet composed throughout its length of two distinct pieces, capable of being separated at pleasure, and then joined again so as to form an air-tight tube. This redoubtable problem, however, is solved in the construction of this curious little instrument that every butterfly carries.
The junction of the two grooved surfaces that form the tube is effected by the same contrivance that reunites the web of a feather when it has 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.