BA'SYLE is the name given by chemists to a simple or compound substance which can unite with oxygen to produce a base (q.v.). Thus, all the metals are examples of simple basyles, and ammonium (NH.), ethyle methyle etc., represent compound basyles. Another property which a B. possesses is, that it can unite with it salt radical (q.v.), like chlorine or cyanogen, to form salts. Thus, the B. sodium (Na) combines with chlorine to produce a salt—in fact, common salt (Neel); and mercury (lig) unites with cyanogen (Cy) to form the salt cyanide of mercury (11gCy).
BAT, the common name of all animals of the class Naninialia which are furnished with true wings, and so are capable of really flying or propelling themselves in the air. They were all included by Linnieus in the genus vespertilio (old Latin name), now sub divided and forming the family vespertilionidce, which is very generally regarded as of precisely equal extent with the sub-order cheiroptera (Gr. band-winged), although some naturalists still follow Cuvier in regarding the galeopithecidce (colugos or flying lemurs) as another family of cheiroptera. But besides other characters which connect the colugos with lemurs rather than with bats, they greatly differ from bats in having a mere extension of the skin.of the flanks attached to the limbs—as in the flying squirrels and petaurists or flying phala»gers, and in the flying dragon among saurian reptiles—capable of sustaining them in the air like a parachute in a very extended leap, but not of being expanded and closed by a succession of strokes for true flight. The power of true flight, bats, on the contrary, possess;..and some of them not only fly rapidly, but wheel about very nimbly in the air, in pursuit of their insect prey.
It is very interestingto compare the organs of flight in bats with those of birds. both RR to the points in which they agree, and those in which they differ. They beat the air, as birds do, with their anterior members; but the requisite extension of surface is not obtained by quills, but by a great elongation of the arms and fingers, upon which a thin membrane is stretched, folding close to the body by means of their joints, when the wing is not In use. A little attention to the accompanying figures of the skeleton of a bat and of a bat flying, will make plainer than mere words can the relation of the bones of a hat's wing to the bones of the human arm and hand, or to the ordinary bones of the anterior extremities in quadrupeds which have fingers or toes. The thumb, a (in figure
of skeleton), is short, armed with a strong nail, and not at all included in the wing-mem brane, nor used in flight. The bones most elongated of all are the metacarpal bones, or hones of the hand, b; the true. finger-bones, c, arc not so much so. The fore-arm, d, has not two bones (radius and ulna), but only one (the ulna), with a sort of rudiment of the other; the rotatory motion, of which these two bones afford the means, being not only unnecessary to bats, but at variance with the purpose chiefly designed in this part of their structure, of a powerful stroke in one particular direction. For a similar reason, "the lingers of this strange hand are incapa ble of closing towards the palm, as ours do, when grasping an object: their only move ments are such as fold up the wing against the side of the body, by laying the fingers close along the side of the fore-arm, as in closing a fan." Great strength, however, was requi site in the shoulder; and, accordingly, we find an analogy to birds in the size and solid ity of the bones in this part, as well as in the thickness of the muscles by which the wings are moved, and still more in the great dimen sions of the sternum, or breast-bone, to which they are attached. The sternum is also fur nished with a medial ridge, as in birds, for the better attachment of the muscles. The ribs arc large; but the other bones generally-, as those of the head and of the pelvis, are delicate, and appear designed for lightness.—The winged membrane of bats extends along the flanks to the hind-legs, although these aid little in flight; but it is attached to them so as to leave the feet free, which are much like the feet of ordinary small quad rupeds with toes and claws, and are employed along with the thumbs of the anterior limbs in creeping upon the ground, in climbing perpendicular rough surfaces, or for hanging with the head downward iu that remarkable posture of repose in which bats pass great part of their lives, and in which they differ from all other animals.