Here are the lemurs, apes, baboons, and monkeys, with their four hands, their climbing cleverness, and their grotesque, ludicrous mockery of man in form and gesture. And here is man himself,-a single species, dispersed through all climes," made of one blood" through all the earth, and everywhere linked to higher worlds, not only by the possession of accountable and immortal mind, but by solemn need of the redeeming mercy of God through the Divine Saviour, and yet so prodigiously various in some of his highest physical conformations, and especially in his speech and customs, that the science of arranging him into his several classes is to the full as intricate as the science of classifying all the mammals.

CHAPTER XV.

THE ECONOMY OF ANIMALS.

SPECIFIC LIFE-AGGREGATIONS OF CELLS THE CIRCULATING SYSTEM -BLOOD-RESPIRATION-THE ALIMENTARY SYSTEM-THE TOOTH SYSTEM-SUMMARY VIEW OF OTHER THINGS IN THE STRUCTURE AND INTERNAL ECONOMY OF ANIMALS-DOMESTICATION—ANIMAL

PROGNOSTICS OF WEATHER-MOULTING-MIGRATIONS-HYBERNATION THE GREGARIOUSNESS OF BIRDS AND BEASTS-THE SOCIAL

PRINCIPLE IN MAN.

THE fundamental wonder in the economy of animals is specific life. "Every organised body," says Cuvier, "independently of the qualities common to its tissue, has a form peculiar to itself, not merely general and external, but extending to the detail of the structure of each of its parts; and it is upon this form, which determines the particular direction of each of the partial movements that take place in it, that depends the complication of the general movement of its lifeit constitutes its species, and renders it what it is. Each part co-operates in this general movement by & peculiar action, and experiences from it particular effects, so that in every being life is a whole, resulting from the mutual action and re-action of all its parts. Life, then, in general, presupposes organisation in general, and the life proper to each individual being presupposes an organisation peculiar to that being, just as the movement of a clock presupposes the

clock; and accordingly we behold life only in beings that are organised and formed to enjoy it; and all the efforts of philosophy have never been able to discover matter in the act of organisation, neither per se, nor by any external cause. In fact, life exercising upon the elements which at every moment form part of the living body, and upon those which it attracts to it, an action contrary to that which, without it, would be produced by the usual chemical affinities, it seems impossible that it can be produced by these affinities; and yet we know of no other power in nature capable of re-uniting previously separated molecules. The birth of organised beings is, therefore, the greatest mystery of the organie economy and of all nature; we see them developed, but never being formed; nay more, all those whose origin we can trace have at first been attached to a body similar in form to their own, but which was developed before them—in a word, to a parent."

Another wonder is the development of the body, the building of the frame, the forming and maturing of the system, of each individual animal. All this is done by the aggregation of cells, and by the subsequent action of the fibres and laminæ into which they are aggregated. But how immensely diversified is it in the different species, how amazing in the simplest, and how prodigiously admirable and inconceivably complicated in the higher! Multitudes of cells are elaborated into the tissues and stomachs and secreting organs of the microscopic animalcule. Millions are worked into the fibres and flesh and vessels and membranes and integuments of the tiniest insect. Different combinations of them deposit the rock of the

corallines, fling off the phosphorescence of the seanettles, form the external skeleton of the crustaceans, and fashion the mantle or the shell of the molluscs. How prodigious, then, must be the myriads, the various arrangements, the ultimate powers of those which build up the muscles and vessels and ligaments and cartilages and bones of any one of the reptiles or birds or mammals!

Another wonderful thing is the circulating system. This cannot be discerned in the lowest kinds of animals, but is very plain in worms and spiders, and becomes increasingly outspread and ramified in the higher and higher orders. It carries nutritive fluid in continual diffusion, in a system of cylindrical vessels, through all parts of the body, and makes deposits of that fluid at every one of the million points which require additions to their organism or repair of their substance. It moves from a centre to the extremities in one set of vessels called arteries, and back from the extremities to the centre in another set called veins; it performs its course variously in one, two, and three circles; and, in all the higher orders, but most elaborately in the highest, it is kept going at great velocity by the powerful, ever-acting, complex engine of the heart. The ramifications and networks and lateral communications and functional forces of its vessels, in every animal, and especially in every mammal, are great and wondrous, far above any ordinary thinker's conception. So minute and manifold are they in man, that a needle's point can nowhere be driven through his skin without piercing one, and letting out its blood; and so powerfully do the large ones near the heart do their office, that the

blood travels through them at the rate of nearly nine thousand feet in an hour.

Another wonderful thing is the blood. This, in insects, is a whitish fluid; and in all the backbonebodied animals is red. In fishes and reptiles it is cold; and in birds and mammals, is warm. In every case, red blood is formed from liquid silling into the veins from digested food, and contains all the elements and principles requisite to build and sustain the whole frame, but is liable to mighty modifications by bad feeding and morbific influences. It comprises a thin serous fluid, which goes easily off at all points of the body to form juices and exhalations, and a much thicker and heavier substance, which has a disposition to coagulate, and trickles slowly out to form flesh and the other solids. All red blood contains the beginnings of life, or is the state of things in which the inorganic product of feeding becomes animated; and it therefore truly lives. When any of it, especially the thick portion, fresh drawn from a living animal, is examined through a magnifying-glass, it is seen to contain multitudes of small globules, of character corresponding to the elementary cells of organic being; and the healthier it is, it contains the more. But it stands only a brief time till it loses them all,-or, in other words, sustains the effects of the loss of life.

Another wonderful thing is respiration. This consists in taking in atmospheric air, combining the oxygen of it with the blood, and giving back nitrogen, carbonic acid, and, in the case of land animals, watery vapour. Part of the oxygen unites with carbon and with hydrogen in the blood to form the carbonic acid and the watery vapour which are ejected, and, in doing