but when he filled similar balls and tubes with bruised grains, and caused them to be swallowed, he found, after a lapse of the same number of hours, that they were more or less dissolved by the action of the gastric juice. In other experiments, he found that metallic tubes introduced into the gizzard of common fowls and turkeys, were bruised, crushed, and distorted, and even that sharp-cutting instruments were broken up into blunt fragments without having produced the slightest injury to the gizzard. But these experiments go rather to prove the extraordinary force and grinding powers of the gizzard, than to throw light upon the positive use of the pebbles swallowed; which, after all, Spallanzani thought were swallowed without any definite object, but from mere stupidity. Blumenbach and Dr. Bostock aver that fowls, however well supplied with food, grow lean without them, and to this we can bear our own testimony. Yet the question, what is their precise effect? remains to be answered. Boerhave thought it probable that they might act as absorbents to superabundant acid; others have regarded them as irritants or stimulants to digestion; and Borelli supposed that they might really contribute some degree of nutriment."

Sir Everard Home, in his "Comparative Anatomy," says: "When the external form of this organ is first attentively examined, viewing that side which is anterior in the living bird, and on which the two bellies of the muscle and middle are more distinct, there being no other part to obstruct the view, the belly of the muscle on the left side is seen to be larger than on the right. This appears, on reflection, to be of great advantage in producing the necessary motion; for if the two muscles were of equal strength, they must keep a greater degree of exertion than is necessary; while, in the present case, the principal effect is produced by that of the left side, and a smaller force is used by that on the right to bring the parts back again. The two bellies of the muscle, by their alternate action, produce two effects—the one a constant friction on the contents of the cavity; the other, a pressure on them. This last arises from a swelling of the muscle inwards, which readily explains all the instances which have been given by Spallanzani and others, of the force of the gizzard upon substances introduced into it—a force which is found by their experiments always to act in an oblique direction. The internal cavity, when opened in this distended state, is found to be of an oval form, the long diameter being in the line of the body; its capacity nearly equal to the size of a pullet's egg; and on the sides there are ridges in their horny coat (lining membrane) in the long direction of the oval. When the horny coat is examined in its internal structure, the fibres of which it is formed are not found in a direction perpendicular to the ligamentous substance behind it; but in the upper portion of the cavity it is obliquely upwards. From this form of cavity it is evident that no part of the sides is ever intended to be brought in contact, and that the food is triturated by being mixed with hard bodies, and acted on by the powerful muscles which form the gizzard."

The experiments of Spallanzani show that the muscular action of the gizzard is equally powerful whether the small stones are present or not; and that they are not at all necessary to the trituration of the firmest food, or the hardest foreign substances; but it is also quite clear that when these small stones are put in motion by the muscles of the gizzard they assist in crushing the grain, and at the same time prevent it from consolidating into a thick, heavy, compacted mass, which would take a far longer time in undergoing the digestive process than when separated and intermingled with the pebbles.

This was the opinion of the great physiologist, John Hunter, who, in his treatise "On the Animal Economy," after noticing the grinding powers of the gizzard, says, in reference to the pebbles swallowed, "We are not, however, to conclude that stones are entirely useless; for if we compare the strength of the muscles of the jaws of animals which masticate their food with those of birds who do not, we shall say that the parts are well calculated for the purpose of mastication; yet we are not thence to infer that the teeth in such jaws are useless, even although we have proof that the gums do the business when the teeth are gone. If pebbles are of use, which we may reasonably conclude they are, birds have an advantage over animals having teeth, so far as pebbles are always to be found, while the teeth are not renewed. If we constantly find in an organ substances which can only be subservient to the functions of that organ, should we deny their use, although the part can do its office without them? The stones assist in grinding down the grain, and, by separating its parts, allow the gastric juice to come more readily in contact with it."

When a paddock is used as a run for a large number of poultry, it should be enclosed either by a wall or paling, but not by a hedge, as the fowls can get through it, and will also lay their eggs under the hedge. The paddock should be well drained, and it will be a great advantage if it contains a pond, or has a stream of water running through or by it. Mowbray advises that the grass run should be sown "with common trefoil or wild clover, with a mixture of burnet, spurry, or storgrass," which last two kinds "are particularly salubrious to poultry." If the grass is well rooted before the fowls are allowed to run on it, they may range there for several hours daily, according to its extent and their number, but it should be renewed in the spring by sowing where it has become bare or thin. A dry common, or pasture fields, in which they may freely wander and pick up grubs, insects, ants' eggs, worms, and leaves of plants, is a great advantage, and they may be accustomed to return from it at a call. Where there is a cropped field, orchard, or garden, in which fowls may roam at certain seasons, when the crops are safe from injury, each brood should be allowed to wander in it separately for a few hours daily, or on different days, as may be most convenient. "A garden dung-heap," says Mr. Baily, "overgrown with artichokes, mallows, &c., is an excellent covert for chickens, especially in hot weather. They find shelter and meet with many insects there." When horse-dung is procured for the garden, or supplied from your stables, some should be placed in a small trench, and frequently renewed, in which the fowls will amuse themselves, particularly in winter, by scraping for corn and worms. When fowls have not the advantage of a grass run they should be indulged with a square or two of fresh turf, as often as it can be obtained, on which they will feed and amuse themselves. It should be heavy enough to enable them to tear off the grass, without being obliged to drag the turf about with them.