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shoot. The growth of the whole body, and the strength and beauty of its form, gradually advance to perfection till the sixth or seventh year, when another change takes place. At this period, the first set of teeth are shed, and are replaced by new ones. From boyhood to puberty, the size of the body, and of its different members, increases. When the age of puberty arrives, several important changes are produced. From this period, to the age of twenty-five or thirty, the muscles swell, their interstices are filled with fat, the parts bear a proper proportion to each other, and man may now be considered as a perfect animal. In this state of perfection and vigour, he generally remains till he reaches his fiftieth year. Then a new, but a gradual change, begins to appear. From the fiftieth year to the age of seventy or eighty, the powers of the body decline in strength and activity. The muscles lose their spring and their force; the vigour of manhood is no longer felt; and the decrepitude of old age is succeeded by death, its unavoidable consequence.

The mind of man undergoes changes as well as is body. The taste, appetites, and dispositions, are in perpetual fluctuation. How different is the taste of a child from that of a man! Fond of gewgaws and of trifling amusements, children frolic away their time without much reflection. When advancing toward puberty, their dispositions and desires suffer a gradual mutation. New instincts are unfolded, and a sense of propriety begins to be perceived. They despise their former occupations and amusements; and different species of objects solicit and obtain their attention. Their powers of reflection are now considerably augmented; and both sexes acquire a modesty and a shyness with regard to each other. This awkward, but natural bashfulness, by the intercourse of so

ciety, as well as by the impulses of nature, vanishes soon after puberty, when the state of manhood commences. From this period, to the age of

twenty-five or thirty, men's minds assume a bold, enterprising, and active tone. They engage in the business of life, look forward to futurity, and have a desire of marrying, and of establishing families. All the social appetites are in vigour; solid and manly friendships are formed; and man goes on for some time to enjoy every kind of happiness which his nature is capable of affording. At fifty or sixty, the mental powers, in general, like those of the body, begin to decline, till feeble old age arrives, and death terminates the scene.

With regard to quadrupeds, both before and after birth, they undergo similar, and many of them greater changes of form than those of the human species. Their mental powers, likewise, their dispositions and manners, as well as the objects of their attention, vary according to the different stages of their existence. Many of them come into the world blind, and continue for some time before they receive the sense of seeing. How many changes are exhibited in the dog from birth till he becomes a perfect animal, till all his members are completely formed, and all his instincts are unfolded and improved by experience and education! The deerkind acquire not their magnificent and beautiful horns before the age of puberty; and even these are annually cast off and renewed. Similar changes take place in quadrupeds of every denomination.

Many birds, like quadrupeds, are blind for some time after they are hatched. In this condition, how different are their form and appearances from those of the perfect animals! At first, they are covered with a kind of down instead of feathers. Even after the feathers shoot, they are often of a colour different from that which they acquire when full

grown. The beautiful variegated colours of the peacock's tail appear not till he arrives at his third year. Birds that have crests, live a considerable time before they acquire these ornaments. All birds annually moult, or cast their feathers, in the same manner as quadrupeds shed their hair.

Frogs, and many other amphibious animals, uns dergo great changes in their form and structure. When it first escapes from the egg, a frog appears. in the form of a tadpole, an animal with a large roundish head, and a compressed or flat tail, but destitute of feet and legs. In this state it remains a considerable time, when the two fore-feet begin to shoot, and have an exact resemblance to the buds of trees. As their growth advances, the toes and legs are distinguishable. The same process goes on with the hind legs, but they are somewhat later in making their appearance. During the growth of the legs, the blood being drawn into different channels, the tail suffers a gradual mortification, till at last it vanishes, and the tadpole is metamorphosed into a quadruped. Tadpoles never come out of the water; but, after their transformation into frogs, they become amphibious, and occasionally frequent both land and

water.

The crustaceous tribes, as lobsters, crabs, &c. beside the different appearances they assume while growing to perfection, cast their shells every year. When this change is about to happen, they retire into the crevices of rocks, or shelter themselves below detached stones, with a view to conceal and defend their bodies from the rapacious attacks of other fishes. After the shells are cast, the animals are exceedingly weak and defenceless. Instead of their natural defence of hard shells and strong claws, they are covered only with a thin membrane or skin. In this state they become an

easy prey to almost every fish that swims. The skin, however, gradually thickens and grows harder till it acquires the usual degree of firmness. By this time the animals have resumed their former strength and activity; they come out from their retreats, and go in quest of food.

Serpents, and many other reptiles, cast their skins annually. The beauty and lustre of their colours are then highly augmented. Before casting, the old skins have a tarnished and withered appear ance. The old skins, like the first set of teeth in children, are forced off by the growth of the new.

But transformations are not peculiar to animals. All organized bodies pass through successive changes. Plants, of course, are not exempted from mutation. What an amazing difference between an acorn and a stately oak! The seeds of plants may be compared to the chrysales of butterflies. The seed, like the chrysalis, contains, in miniature, all the parts of the future plant. These parts require only time, and other circumstances necessary to vegetation, for their complete evolution. How different are the seed-leaves from those of the plume! Beside the general changes arising from growth, plants undergo a number of metamorphoses from other causes. In northern climates, if we except a few evergreens, trees, during winter, are entirely stripped of their leaves. Instead of the pleasant emotions excited by the variety of figures, movements, colours, and fragrance of the leaves, flowers, and fruit, during the spring and summer, nothing is exhibited in winter but the bare stems and branches. In this state, the trees of the forest have a lugubrious appearance. Very different are the emotions we feel in spring, when the buds begin to burst, and the leaves to expand. When summer approaches, another beautiful change takes place. The flowers R

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with all their splendour of colours, and sweetness of scents, are then highly delightful to our senses. After performing the office of cherishing and protecting the tender fruit for some time, the flowers drop off, and a new change is exhibited. When the flowers fall, the young fruit appear, and gradually grow to maturity, perpetually presenting varieties in their magnitude, colour, odour, and flavour. When the fruit and seed are fully ripe, they are gathered for the use of man, drop down upon the earth, or are devoured by birds and other animals. After this change happens, to which all the others were only preparatory, the leaves begin to shed, winter commences, and the same series of metamorphoses goes on during the existence of the plant.

and

The changes just now mentioned are annual, are ultimately intended to supply men and other animals with food. But plants are subjected to changes of form from causes of a more accidental nature. Varieties or changes in the figure of plants are often produced by soil, by situation, by culture, and by climate.

Thus it appears, that, in both the animal and vegetable kingdoms, forms are perpetually changing. The mineral kingdom is not less subject to metamorphoses. But though forms continually change, the quantity of matter is invariable. The same substances pass successively into the three kingdoms, and constitute in their turn, a mineral, a plant, an insect, a reptile, a fish, a bird, a quadruped, a man, a man. In these transformations, organized bodies are principal agents. They change or decompose every substance that either enters into them, or is exposed to the action of their powers. Some they assimilate, by the process of nutrition, into their own substance; others they evacuate in different forms; and these evacuations make ingredients in the compositions of other bodies, as

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