Imágenes de páginas

but slight : our aim is to touch upon points more especially interesting to the general reader ; while, at the same time, we shall endeavour to furnish some illustrations of the wisdom of that great, all-powerful God, who has condescended to reveal himself to fallen man, not only as the God of nature, but also as the. God of providence and grace.

In the fulfilment of our plan, we shall endeavour to avoid the use of technical terms, even at the expense of precision of language; for, unless the reader be perfectly familiar with them, such terms tend to embarrass and perplex, perhaps even to deter him from pursuing a subject replete with instruction and well calculated to expand the intellect.

By way of introduction, it may be desirable to take a brief and general survey of the animal kingdom, in order that some idea may be entertained relative to its extent, and the vast multiplicity and diversity of beings which it comprehends—from man downwards to the microscopic animalcule. For every

conceivable mode of existence are animals created, and with parts, form, and organization adapted to their several exigencies. Setting man out of the question, highly exalted

as he is above the nearest of the brute creation, whose prospects are not bounded by the decay of his earthly body, the tenement of a spirit which never dies--some animals are much more elevated in the scale of being than others, and more sensitively enjoy existence, while death, not being anticipated, is but the pang of the moment. In these animals, a brain encased in a skull, and a spinal cord connected with the brain, and protected by a series of bones forming the vertebral column, are always present. Nevertheless, great is the difference between animals thus endowed; and widely do they vary in habits, manners, food, and instincts. Some are furnished with limbs, and have the body clothed with fur; they breathe the air, they traverse the ground, and range mountain and valley, plain and forest, desert and morass -we allude to quadrupeds; but of these, some, as the seals, are very aquatic in their habitswhile others are completely so, as the blubberclad whales, which, though not possessing four distinct limbs, belong to this class : they plough the great deep. There is, again, a class of air-breathing animals clad in feathers, and furnished with four limbs, of which the anterior pair are constructed as instruments of flight.

They rapidly traverse the air on wings, but they repose on the ground, in the trees, or on the surface of the water; hence birds are structurally modified for very diverse modes of life. Quadrupeds produce living young, but birds lay eggs, upon which the parent incubates, in order that the warmth communicated by her body may cause the development of the chick. Both quadrupeds and birds have warm red blood.

As we descend the scale, we come to groups in which the blood is cold, and the body is defended either with bony plates or shields, with a sort of tesselated horny armour, with scales, or is destitute of any covering. Some of these animals have four limbs, some two, some none. Many are aquatic in their habits, others terrestrial, and others arboreal. The greater number breathe air; some are constructed for both aquatic and atmospheric respiration. Some, during the first stages of their existence, are fitted for aquatic respiration exclusively; but, afterwards, from a strange alteration of structure, lose the power of aquatic respiration, and breathe only air. We allude to reptiles and amphibious creatures to tortoises, crocodiles, lizards, snakes, sirens, and frogs; animals

which exhibit a wide range of structural variation, and habits and instincts of the most opposite character.

Last in the series of animals with a brain and spinal cord comes the vast variety of fishes. These animals are expressly constructed for the water in which they are destined to live, and through which many dart along with almost inconceivable velocity. They are furnished with gills for the purpose of aquatic respiration; their bodies are generally somewhat cylindrical, compressed at the sides, with a sharp pointed head, and an elongated muscular tail, terminated by a fin, which is the great instrument of locomotion, the fins of the body acting chiefly as rudders and balancers. However, there is great difference in the form of fishes, and, consequently, in the ease and celerity of their movements, and in their habits. Some have large heavy heads, as the cod-fish, and move leisurely--some are almost globular, as the tetraodon, which has a habit of floating on the surface of the water-some, again, as the skate, are depressed vertically, and are termed flatfishes—some are compressed laterally, with the head twisted, or, as it were, distorted, so that both eyes are on the same side, such is the

sole-others, again, are elongated and somewhat snake-like, as the eel.

Most fishes are covered with scales, arranged in regular order ; in some species, however, they are so minute, that, in a popular sense, the fish may be called naked, as, for example, the eel. In several species the skin is rough, being minutely granulated with hard tubercles. Some, as the pipe-fish and hippocampus, are invested with a sort of armour of indurated or horny plates; while in others, as the ostracion, these plates are so consolidated as to form a sort of bony box, the tail, the fins, and the mouth being alone movable.

It is not only by scales, or other appendages, that the skin of fishes is defended from the action of the water in which they dwell—they are externally lubricated by a tenacious slime the secretion of certain glandular pores, whence it exudes abundantly. Most fishes produce eggs in vast numbers, collectively termed the roe; but some of the sharks are viviparous, and so is the angel-fish, (Squatina angelus.) This observation applies to reptiles, these animals being, as a rule, oviparous, with the exception of a few lizards, and certain venomous snakes, which produce living young.

« AnteriorContinuar »