That these observations are not, however conclusive, appears from an experiment of a very ingenious naturalist: being desirous of ascertaining the nature and use of the antennæ and proboscis of a butterfly, he gently approached one that was flying about in search of food; he observed that it turned the antennæ about every way, till coming within scent of a flower, it kept them fixedly bent toward that object, directing its course by their guidance, till it arrived at the flower; there they appeared to act as an organ of smell, and that the minute holes with which it is furnished assisted in promoting this operation. When the creature had reached the flower, it hovered over it as with rapture, poising itself quietly upon its wing, like a kite or hawk in the air; it then dropped suddenly, till it was on a level with the flower, when it began to agitate its wings briskly and to unroll its spiral trunk, thrusting it to the bottom of the flower; in a little time the trunk was rolled up, and again in a moment unrolled; these operations it repeated till the flower yielded no more juices, the butterfly then sought for and alighted on another.[54]
[54] After all, this subject must for the present remain undecided. Indeed, the bodies of insects are throughout formed of parts so different from ours, that we can probably conceive no more idea of the use of some of their organs, than a man born blind or deaf can of the senses of vision or hearing. They may have senses different from ours, and these may be the organs of them. EDIT.
The differences in the form, &c. of the antennæ are characterized by naturalists under the following names:
Setaceæ; are those that, like a bristle, grow gradually taper towards the point or extremity, as in many of the phalenæ. Filiformes; thread-shaped, and of an uniform thickness. Moniliformes; these are filiform like the preceding, and of a regular thickness, but consist of a series of round knobs, like a necklace of beads, as in the chrysomela. Clavatæ; formed like a club, increasing gradually from the base to the extremity, as in the papilio, butterfly. Capitatæ; these are also formed like a club, but the last articulation is larger than the rest, finishing with a kind of capital or head. Fissiles; these are like the former, only that the capitulum or head is divided longitudinally into three or four parts or laminæ, as in the scarabæi. Perfoliatæ; are also capitated, but have the capitulum divided horizontally, and the laminæ connected by a kind of thread passing through their center, as in the dermestes and dytiscus. Pectinatæ; so called from their similitude to a comb, though they more properly resemble a feather, as in the phalenæ and elateres; this is most obvious in the male. Aristatæ; such as have a lateral hair, which is either naked, or furnished with smaller hairs, as in the fly.