While the down remains, a marvellous apparatus is being formed, which may be called a feather manufactory, for a mould is made for every feather. When first visible, this organ has the form of a very minute capsule (B), which rises above the cuticle, and is attached by a filament proceeding from its base

to one of the papillæ of the skin, thus establishing its connection with the living system. In a few days this cone has become a cylinder (Fig. 1) with a pointed extremity (A), while its base (B) is united to the true skin by a more distinct bond of connection, formed by the enlarged vessels, which are supplying it with nourishment.

At the time, too, in which the outer covering of the shaft is growing in one place, the spongy substance is deposited in others. The parts which form the vane of the feather are, however, produced first. They do not grow from the base, like hairs from the head, for all the materials composing the fibres are cast into moulds, where they harden, and acquire their exact shape. The smaller parts, called fibrils, are probably formed in moulds still more minute.

As the parts of a feather thus advance below, those which are completely formed rise above the skin, carefully covered, however, for a short time; after this they unfold, and assume their proper shape. On the feather being perfected, the substance which forms it dries up, the blood-vessels which nourish it disappear, and thus we have the pith, which is removed before making a pen. Geese are sometimes plucked too soon, the feathers being still young; hence the soft barrel is gorged with blood.

Marvellous as all this is, it should be observed that this feather manufactory is not merely in action once during the life of a bird; for all its feathers are generally moulted annually, and even at shorter periods. A new mould must, therefore, be produced every time a new feather is formed.

1.

B

3.

KKKK

1. Productive Capsule, A, B. 2. Capsule opened. Outer Capsule, c. Pulpy Mass, B 3. Conical-shaped Membrane, as the stem is filled up.

"Light as a feather," has long been a proverb; but a feather is also remarkable for its strength. In the upper part of the shaft is a material, used in no other class of animals, and, indeed, in no other part of birds. As the pith is neither bone nor flesh, membrane nor tendon, it is a very peculiar substance, and, like the former, it is made and used for one special purpose. The quill is partly composed of circular fibres, which must be scraped off in making a pen, or else it will split roughly, and make what boys call "cat's teeth." This part serves as a sheath while the feather issues from the skin, and during its future growth.

THE GROWTH OF A FEATHER.

The shaft will be found divided into two portions by a long groove, and from each side proceed the parts which form the vane (v). One of these is usually stripped off in making a pen. The vane is formed to oppose proper resistance to the air. Rub the feather up and down in the line of the stem, and no difficulty will arise; but press it in the direction of its greatest width, and it will resist the effort. Now, the impulse of the air occurs just where the feather does not yield; here, therefore, it wants strength, and here it has it.

VOL. III.

2

The resistance thus presented arises from a number of fibres, on the margins of which, as the microscope shows, there are fibrils, fitted to unite together, a thousand of which have been counted in the space of an inch. (See cut, page 9.) They are of two kinds : one branched, or tufted, and bending downwards; the others, not divided into branches, but directed upwards. They act like the fingers when the hands are clasped together. The interlacing of these fibrils causes the close texture of the vane. When they are separated by accident or force, and are brought together again, they reunite at once, and the vane is as firm and smooth as it was before. If the finger be drawn down the feather, against the grain, perhaps some of the fibrils will be broken off; but, if it be drawn the other way, all of them will appear in order.

The part of the plumage first wanted is always the earliest produced. Thus, when wings are not needed so soon as clothing, the coat of down precedes the pinions. A young partridge, for instance, is no sooner hatched than it runs off to pick up the chrysalis of the ant, which the parent scratches up for her brood; hence, from the first, the body is defended by a close-set downy covering, while all the strength of the bird is given to the thighs, legs, neck, and bill-the parts actually in use. It is not necessary that the partridge should fly for some time, and therefore the wings are afterwards gradually formed. Not so is it with the young blackbird or thrush: this bird must fly as soon as it leaves the

nest; and hence, while its body shows only a few scattered bunches of weak, downy, hair-like feathers, the quills and other wing-feathers are very rapidly formed.

The plumage of the male bird is generally far more brilliant than that of the hen; and, when it is so, the young always put on first the plainer dress of the mother. When there is little difference between the two, the young have a particular and distinguishing attire of their own.

Colour is intended not merely for beauty; it is, in fact, a mode of concealment, the most universal of all means of defence, and one that appears in every race of animals. As the strength, the weapons, and the velocity are all on the side of the pursuer, colour is much more resorted to for the defence of birds than of any other creatures. In the partridge, the quail, the woodcock, and the snipe, the likeness of their colours to the brown earth on which they move is such as often to conceal them from every eye, not excepting the piercing sight of the hawk or the kite. The hovering foe may be observed above during the chase, though the victim has not escaped, deceived also by smaller birds, even when the accordance in colour is not great. Often do they shift their position under the eye of a hawk eager to pounce upon them, and then stop, as if, as White says, "they knew the colour of the spot on which they are cowering and squatting was a sure defence."

Of this there is a special instance when the males are provided with the most beautiful plumage, while the females are attired in a dull, earthy colour, so that they can scarcely be distinguished from the ground on which they sit. This difference particularly appears in the pheasant, peacock, and duck tribes.

In the wings there is an osseous framework, acted upon by muscles, the tendons of which are respectively inserted into the several bones composing it, the whole being covered with skin, and affording a solid basis, on which the feathers rest. The wing, which is, in fact, the arm of the bird, consists, as in man, of the true arm, the fore arm, and the hand.

The true arm is formed of the humerus (h), a cylindrical and hollow bone, the head of which is received into a shallow cavity of the scapula, or shoulder-blade (a), at the angle made by the sudden turn and descent of the large coracoid process, which is attached at its posterior extremity to the anterior margin of the breast-bone. The fore arm consists of an ulna (b), and a radius (c), which is very slender. The ulna has often a row of tubercles on the upper surface, denoting the situation of the barrels of the secondary

quill feathers, to which it yields support. The hand is divided, as usual, into carpus (d), metacarpus (e), and phalanges; but, so far from being flexible, as the name suggests, it is a firm, inflexible basis for a series of stiff, elastic feathers, continuous with those proceeding from the ulna. On the anterior edge, and at the base of the metacarpus, is seated the thumb bone, a singlejointed piece (f). The fingers (g) are two: the first consists of two phalanges, a broad basal bone, as if several were compacted into one, and a small pointed bone. The second finger consists merely of a small portion in close contact with

WING OF A BIRD.

the first phalanx of the first finger. The hand, thus formed, is as perfectly adapted to its circumstances as the hand in man, to which it bears, however, only a slight resemblance.

The feathers arising from the hand and ulna are termed quill feathers, and are divided into two sets. One arises from the hand, consisting of the most important of the series, and chiefly instru

mental, by their length and shape, their stiffness or flexibility, in determining the character or power of flight. These are the primary quill-feathers (No. 1): they are ten in number, but differ in form as well as relative length. The other set arise exclusively from the ulna, and are the secondary quillfeathers (No. 2); they are usually shorter, broader, and less rigid than the former, and the number varies. From the small bone which represents the thumb arise certain short, stiff feathers, lying close on the quills of the primaries, and constituting the winglet, or spurious wing (No. 3). There is also a group of feathers termed tertiaries, arising from the humeral joint of the fore arm, and which, in many birds,

as the curlew, plover, lapwing, &c., are very long, and form a pointed appendage very apparent during flight. In most birds, however, they are not to be distinguished from the rest of the greater coverts (No. 4), of which they are, in fact, a continuation. Other feathers, attached to the upper part of the humerus, lie along the sides of the back, and in many birds they are of great length; they are called scapularies (No. 5.)

A series of feathers, termed the lesser coverts (No. 6), are disposed in scale-like order, row after row, on the fore arm and carpal joint. The quills of the tail-feathers are hidden beneath the upper tail coverts (No. 7). Beneath are the under tail coverts (No. 8). A tuft of feathers form the ear coverts (No. 10), and the tail (No. 9), has only to be mentioned to complete a general view of the plumage of birds.

When the longest feathers occupy the edge side of the wing, and then go on decreasing, the wing

is acute; when the longest feathers correspond with the middle of the hand, the wing is obtuse. Each of these types may offer three cases: when the second feather of the wing, beginning from the edge, is the longest, the wing is simply acute; when the first feather is as long, or longer, than the others, the wing is sur-acute; when the third feather is equal to the second, the wing is sub-acute. In like manner, three degrees have been established in the obtuse wing: if it is on the fourth feather, which is the longest, it is simply obtuse; if it is the third, it is sub-obtuse; if it is the fifth, or following, it is sur-obtuse. The bird with acute wings moves with greater agility than the one whose wings are obtuse; hence, the one has been called a sailing bird, and the other a rowing bird.

One of the laws of motion is, that action and reaction are equal-that is to say, that whenever one body exerts a force on another, the second body opposes the first, with equal force, in an opposite direction. When, for instance, a boy runs with his kite against the wind, he strikes the air, and thus produces a reaction, which is equal to the force given to it. When the wind is high, and its action is not intercepted by surrounding objects, there cannot exist any necessity for such an expedient.

In like manner, if a bird strikes the air below it with a force which is equal to its weight, then

must there be a reaction of the air, upwards, exactly equal to it; and the bird, being acted on by two equal forces, in opposite directions, will, necessarily, rest between them. But as the force of the stroke is greater than the weight of the bird, it therefore rises with the difference of these forces; were the stroke less than its weight, then would it sink with the difference. If, for example, a bird weighs twelve ounces, and it strikes the air with a force equal to sixteen, it must rise with a force equal to four; and if it strikes the air with a force equal only to eight, it is equally clear that it must sink with a force equal to four.

The flight of birds is, sometimes, very extraordinary. M. Adamson caught swallows on the coast. of Senegal, which arrived there eight or nine days after their departure from Europe. A falcon, eagerly pursuing a smaller bustard at Fontainebleau, was taken the following day at Malta, being recognised by the ring she bore. And to mention only one more instance: at Barbadoes, the sea-gulls proceed in flocks to a distance of more than two hundred miles, and return again the same day!

The tail of a bird differs, in its action and uses, from the rudder of a ship. The rudder, for example, is so fixed that it can only move in one horizontal plane, and can therefore only turn the vessel to the right or left, which, indeed, is all that is required; but the tail of a bird, in addition to this motion, can be placed in a diagonal direction, and, when expanded, will offer a considerable

surface to the air, so as to fulfil some of the offices of a third wing. If, for instance, a rook be watched as he gambols through the air, it will be seen that, after flying in the ordinary way, his wings are at rest, and that he glides along without the least exertion in his descent. In this case his expanded wings act as a parachute; then, again, he will be observed wheeling round-a manœuvre which is partly produced by the oblique position of his tail. The tail, too, serves to poise the body of the bird.

The wings are used to direct the bird in its course, and the tail acts as a supplementary organ. Thus, it is evident that it can easily turn, either to the right or left, by flapping the opposite wing with increased force, just as a boat is turned about to the right, by a brisk application of the left oar. And hence, the more rapid the flight is forward, the greater is the difficulty of one wing surpassing the other in velocity; and less sudden are the deviations. This is the reason why the birds which fly with the greatest velocity make large circuits in turning. In like manner, the irregular flight of the butterfly, now up and now down, now to the right and now to the left, is, probably, effected by the wings striking

the air one after the other, or, perhaps, with an alternate and unequal force. The object of such an action is to baffle the pursuit of birds which fly in a right line, whereas the butterfly does just the contrary.

NICTITATING MEMBRANE.

Of the five senses, sight, smell, and hearing are the most acute in birds. To begin with the first: the bony orbits are of great magnitude, and the organs of vision contained in them are proportionably large. In the birds of prey, "the orbits have the shape of a chalice," says Blumenbach, "or cup used in the communion service. The cornea, which is very convex, forms the bottom of the cup, and the posterior segment of the sclerotica resembles its cover. This peculiar form arises from the curvature and length of the bony plates, which, as in all other birds, occupy the front of the sclerotica, lying close together, and overlapping each other. These bony plates form, in general, a flat or slightly convex ring; being long and curved, as in the hawk, they form a concave ring, which gives the whole eyeball the above-mentioned form." By means of this ring, the eye becomes a kind of self-adjusting telescope, so as to take in both near and very distant objects.

The crystalline humour is flat in birds, and the vitreous humour is very small. The colour of the iris varies in different species, and in many cases is very brilliant. They have three eyelids, two of