and grubs moths. Silkworms, however, become moths that neither fly nor eat.

Insects of the hemiptera order, as locusts, crickets, grasshoppers, the walking leaf of China, Peruvian lantern-flies, and others of the fulgora genus, want little of perfection when they issue from their eggs. They undergo, therefore, but little change from infancy to age. But, in general, insects exhibit themselves in three separate states after issuing from their eggs the larva, the pupa, and the imago states. These, however, are merely so many separate stages in the development of the insectile organs, every insect having, in its earliest state, all those organs in miniature which they afterward seem to acquire. Thus in the most helpless of larva may be recognised through a microscope all the rudiments of a perfect insect.

The frog proceeds from an egg in the form of a roundish black or brown substance, having a tail. In ninety-seven days eyes appear, and in two days more arms, when the tail drops and the animal becomes a perfect frog. Toads are formed in a similar manner. The frogfish of Surinam even returns to its original state: it is first a fish, then a frog, and after many years changes to a fish again.

Caddice-worms, enclosed in cases formed of sand, leaves, and minute pieces of wood, crawl along the bottoms of quiet streams, become perfect insects, rise to the surface, quit their houses, hover over the stream, drop their eggs into the water, and die. The ephemera tribe reside for three years in brooks and rivers in their reptile state, having gills like fish. After passing their aurelia stage, they emerge from the water in a shape resembling that of the butterfly; but their lives are prolonged only to the extent of a few hours: they drop their eggs, fall to the earth or into the water, and die almost immediately after.

The larvæ of the libellula tribe also remain for

two or three years in the water. They then creep to the top of a plant, burst their covering, and fly into the air. Gnats, when they issue from their eggs, are worms, which reside at the bottom of standing waters. These worms change their forms, assuming large heads and hairy tails. Soon, however, they divest themselves of this appearance by parting with their antennæ, tails, and eyes: their heads then become invested with a plume of feathers, and their bodies covered with scales and hair. Minute feathers are attached to their wings, and they are furnished with a trunk of exquisite formation.

The pulex irritans issues from an egg in the shape of a worm, of a pearl colour. In a short time it hides itself, spins a thread from its mouth, and after laying enclosed in the covering it thus forms for a fortnight, issues from its confinement a perfect animal, defended by a species of armour.

The lion-ant, after remaining in its reptile state from one to two years, spins a thread, which, being glutinous, sticks to small particles of sand, and in this it rolls itself up like a ball. Here it continues for six or eight weeks, when, gradually parting with its skin, feet, antennæ, and eyes, it pierces a hole through the ball, and appears in the form of a fly, having a brown slender body, a small head, large eyes, long legs, and transparent wings.

May-bug beetles deposite their eggs in the earth, from which the young creep out in the shape of maggots, and live in the earth for three years, feeding upon roots. While under ground they change their skin every year, and at the end of the fourth dig themselves a cell, cast their skin, and pass into the chrysalis state. In the succeeding May they burst from the earth, unfold their wings, and fly round the tops and sides of trees.

The ox gadfly introduces its egg into the skin of the ox, and it produces a yellowish maggot. This maggot falls to the ground, burrows, and enters into

the aurelia state, whence it issues a fly of a pale yellowish brown colour, marked with dusky streaks, and about the size of a bee.

Some worms lodge themselves under the tongues of dogs, others in the nostrils of macaws, and some in the heads and even throats of deer. I once put a moth among some leaves under a glass. It deposited several eggs and died. In a few days the eggs, being placed in the sun, burst, and out of them crept insects with wings, resembling their parent as little as turtles resemble an elephant.

As the human being approaches old age, the skin, flesh, and fibres become more dry and hard. Digestion is more difficult; there is less perspiration; the circulation of the blood is languid, and life fades away by insensible degrees. This decay seems to arise out of the circumstance that the carriers of matter for the repair of the vascular system cannot carry enough wherewith to repair themselves.

The act of converting food into animal matter is chiefly performed by the stomach, the gastric juice found in it constituting the chief menstruum. By a process at once simple and intricate, food is converted into chyme, which, uniting with the bile and other juices, is formed into chyle, a substance_resembling milk. This chyle is conveyed by the lacteal vessels to the heart. In this reservoir it begins to form blood, which, passing through the lungs, is modified and perfected by respiration, and by one of the most beautiful of processes is distributed by the arteries, and strained into the proper vessels, converting vegetable and animal subtances into nerves, sinews, flesh, bone, and every other part of the human machine, as vegetable juice is indurated into amber, and the leaf of the mulberry formed into silk.

Other changes take place in the animal system which would lead us too far into technical peculiarities. But there is one circumstance too curious to

be overlooked: it belongs to the ear. While all the other bones of the human frame increase and acquire strength by time, those that lie in the cavities of the ears are perfect even before birth. They may therefore be said to have a longer duration in respect to perfection than any other part of the human body. As to those changes which are caused by the vibratory motion of the nerves, begun by external objects and propagated to the brain, they are so numerous and so delicate that it would require a volume of no ordinary magnitude to explain them, and even then the subject would be but partially treated.

All animals are compounded of vegetable substances. The hoof of the horse; the horn of the cow; the shell of the snail; the teeth of the elephant; the claw of the lion; the feathers of the dove; the wool of the sheep; and the hair of the camel, all once grew, as it were, in the fields. The eyes with which we see, and the ears with which we hear; the blood of our fathers, the arms of our sons, and the cheeks of our daughters, are all ultimately derived from vegetables, having their roots in the soil, and drawing their sustenance from it; proving the truth of the doctrine that man came from the "dust."

ANALOGIES BETWEEN PLANTS AND ANIMALS.

PLANTS claim some affinity with animals. The stalk of the former resembles the body of the latter; the root the stomach; the bark the skin; the pith the marrow, and the juice the blood. Like animals, too, plants are subject to a great variety of disorders. They imbibe air and moisture by their leaves, and food by their roots; both being transmitted into their own substance, as theirs is after

ward into the substance of animals; for the entire frame of animated being derives its form and its consistence from vegetable organizations.

Some writers confound sensation with the power of motion; and if no motion is perceived, they cannot imagine the existence of sensation. But oysters have no more the locomotive power than thistles; and they can no more forsake the beds in which they are deposited by the tide, than fishes can swim without water, or birds and insects fly without air. Vegetable sensation, however, is not animal sensation; and it is no feeble mode of supporting this argument to remark that, as Nature furnishes compensations to all, she would never have ordained so cruel a result as animal sensation to plants, without giving in turn the power of defence. A few plants, it is true, seem to be endued with this faculty; some by the noxiousness of their qualities, and others by the peculiarity of their structure; as the nettle, the thistle, the noli me tangere, the thorn, the rose, the holly, the kamadu of Japan, with the deadly nightshade, and other poisonous plants. Yet these plants, armed as some of them are against attacks, and as others are against animal use, support innumerable insects. Some plants open their petals to receive rain, others avoid it. Some contract on the approach of a storm, and others åt the approach of night; while some expand and blossom only to the evening air. Near the Cape, certain flowers form a species of chronometer. The Moraa unguiculata and undulata open at nine in the morning, and close at four; the Iria cinnamonea opens at the time the other closes, and sheds a delicious perfume during the night. The Mexican marvel of Peru also closes at four.

The stamina of the flowers of sorrel-thorn are so peculiarly irritable, that when touched they will incline almost two inches; and the upper joint of the leaf of the Dionaa is formed like a contrivance