for smelling, and the lower pair for tasting; while Lehmann says, that "whoever undertakes to deny that they are organs of touch, proves thereby that he has not observed living insects *" Cuviert and Dumeril express a similar opinion, supported chiefly by the observation, that most insects, when they walk, apply their palpi incessantly, or very often, to the surface upon which they are moving; while spiders sometimes employ them as legs, and scorpions as hands. They are always put in great activity when the insect is feeding.

To us the most probable opinion appears to be, that the palpi may be used somewhat in the same way as we employ our lips and tongue, both as instruments of touch and of taste; their situation near the mouth suggesting this, though they are otherwise little analogous in site or structure. This opinion is supported by the consideration that one of the chief employments of insects being the search after food, they are thence led to apply their palpi incessantly for its discovery, and also for ascertaining its capability of being consumed, should the discovery be originally made by means of smell. In this respect

insects act much in the same manner as the human infant. Every body must have remarked, that a young child carries every thing to its mouth, whether it be hungry or not, and the only design of this seems to be the examination of the object. We may often, indeed, see a child pressing its gums with whatever comes in its way, to allay the uneasy sensations occasioned by the protruding teeth; but even when this is not the case, it carefully tries every thing both with the mouth and with the hands, holding the object at different distances from the eye, *De Sensibus Externis, page 38, + Anatomie Compar. ii. 676. Considérations générales, p. 9.

and grasping it in various directions and positions. In a word, instead of being, as most people suppose, engaged in an idle and unprofitable amusement, the infant is employed in eager study and examination, in order to learn the effects of the qualities of objects upon its senses. The insects, on the other hand, are too short-lived to require the same multifarious knowledge of hardness, softness, distance, and form, and hence they only employ their palpi in examining what may be proper or improper for food.

An important organ of touch in insects, as it appears to us, has been altogether overlooked by naturalists. We refer to the surface of the wings, minutely furnished, as they appear to be, with nerves for this express purpose. It must be this, indeed, which, in a great measure, serves to direct their flight, as the focus of their eyes appears, according to our ideas of senses, to be too short for this purpose. We have elsewhere remarked, that the marsh fritillary butterfly (Militæa Artemis, OCHSENH.) seldom flies beyond the field in which it is produced *; but this is not so remarkable in insects of slow and heavy flight, and in a field hedged in, as in those of rapid flight and restless disposition, in the open country. We remarked, for several weeks, near St. Adresse, in Normandy, a very limited spot, close by the sea, to be daily frequented by about half a dozen of the clouded yellow butterfly (Colias Edusa, STEPHENS), which seemed to make a regular circuit, and return again, altogether independent of the direction of the wind, against which they often made way. Now, as they often rose to so considerable a height that they must have lost sight of the ground, we conclude that they guided their flight more by the weight of the superincumbent air than by the direction of the wind-an inference rendered more probable by *See Chapter on Migrations,

their never being seen on the heights which there rise steeply from the shore *.

a Clouded yellow butterfly (Colias Edusa), male.
b Pale-clouded butterfly (Colias Hyale), female.

It is, probably, in part through the information derived from the varied impression of air on the wings that bees can return so unerringly to their hives; and hence the reason of their flying in curves and circles both when they depart and return, a circumstance

* J. R.

C

which Huber more particularly remarked in the queenbee, when she left the hive for the purpose of pairing. Carrier pigeons, we have also remarked, employ the same circular mode of flight, both in departing from an unknown station and in arriving at their home from a distance.

These facts are strikingly illustrated by the extraordinary delicacy of touch possessed by bats, which made Spallanzani conceive that they had a peculiar sense distinct from any found in other animals; and, to satisfy himself upon this point, he performed many cruel experiments. He found that bats, when blindfolded, and even when their eyes are destroyed altogether and leather glued over the sockets, can fly nearly as well as before, and can avoid in their flight the smallest threads and other objects hung up to interrupt them. They can even dart through a hole in a net or curtain, large enough only to admit their passage, and that without previous examination. They can likewise thread the mazes of a cavern, without hurting themselves on the walls, and go directly to their nest-holes. When Spallanzani destroyed the ears and nostrils, as well as the eyes, of bats, he found that they could direct their flight equally well.

The correctness of these statements was verified by Professor Jurine, of Geneva, and by Sir A. Carlisle, who repeated the experiments; but it was Cuvier, if we mistake not, who first gave a plausible explanation of them. He considers the wing of the bat analogous to the hand, with the fingers very much elongated, and united by membrane; and as it is not only of great extent, compared with the body, but is one continued tissue of exquisitely sensible nerves, covered with a fine skin, furrowed like that on the human fingers, the delicacy of its touch is by no means marvellous. If this be correct, the blinded

bat is guided wholly by the impression of the air on its wings and yet we have observed bats, confined in a house, beat themselves against the windows, as wild birds and bees will do, though never against the walls*. Man has the same means of knowledge in a slight degree: for it is easy in the dark to say when one approaches a wall, by the impression of the air on the face. The faculty in the bat of perceiving, and being able to avoid such obstructions, is a provision of creative wisdom well worthy of our notice, as the creature, always flying in the twilight and in the night, could not well depend on its eyes in avoiding objects during its rapid flight in pursuit of nocturnal moths. Moths, and most night-flying insects, possess this faculty in an inferior degree. Beetles, indeed, seem to be deficient either in the power of perceiving objects or of avoiding them, as they often, during the twilight, dash against the traveller, (from which originated the proverb of "blind as a beetle"); but we have never observed any of the night moths thus deceived.

The feeling of the various degrees of temperature, whether hot or cold, is so different from the other perceptions of touch, that some naturalists, among whom are Darwin and Fleming, refer it to a peculiar sense. As insects appear to be extremely susceptible of varying temperature, we must not pass it over without notice. Dr. Fleming distinguishes what he terms the sense of heat from touch by its not requiring, like the latter, any muscular effort for its exerciset. That there are peculiar nerves in various parts of the skin appropriated to the perception of heat, Dr. Darwin thinks is proved by the heat of a furnace giving no pain to the nerve of the eye, while it scorches and pains the parts adjacent. Warm water, again, or warm * J. R. ↑ Philosophy of Zoology, i. 171.