VOL. I.

THE NATURALIST.

FEBRUARY, 1831.

No. II

[Since the publication of the first number of this work, several of our patrons have urged the necessity of a Glossary, or explanation of some of the elementary terms employed in Natural History, for the benefit of those who have not made much advancement in the science. Our object at the commencement of this work was, to use as few technical words as possible; and such as we could not avoid, to explain at their places; but we will present the following sketch, which will give a general view of the subject.]

THE science of Natural History comprehends a description. of every material substance, organized and inorganized, animate and inanimate, that exists naturally within and upon this globe, including the atmosphere. In other words, it embraces every earthly, material object that is not artificial. Those who with a philosophic eye have contemplated the productions of Nature, have all, by common consent, divided them into three branches, viz: Zoology, Botany and Mineralogy.

I. ZOOLOGY.

Zoology is the science which treats of material, organized beings, which are endowed with the sentient or perceiviug principle. In short, it includes every earthly being that grows, lives and feels.

We find it somewhat difficult to draw a line of distinction between the different kinds of organized beings, that is, animals and vegetables; the lines of distinction often seem to fade so gradually, that we cannot well decide where the animal ends and the vegetable begins. It is generally true that animals differ from vegetables in possessing locomotive, as

well as sentient powers. This is a good distinction between. the ox and the oak; but is very deficient when applied to the isis and the sensitive plants.

Animals receive their food into internal cavities, which are so modified as to furnish the fluids which supply the wants of the system. And probably no substance is received as the food of animals, which has not previously been in an organized state. Whereas vegetables receive inorganic matter for food, as well as that which has been organized; and their food is chiefly received through tubular radicles, or pores of leaves, which have the power to direct their courses or pores towards water, air, light and heat.

All animals have the sense of feeling. But they have no particular organ for that sensation; it is depending on papillæ, or small protuberances at the ends of the nerves, which terminate in every part of the skin. All vertebral animals have

four organs of sense. Each organ is adapted to its particular office. One for communicating the sensation of sight, one for sound, one for taste, and one for smell. Some of the other divisions of animals have more or less of these organs in greater or less perfection.

All animals seem to require a system of organs for digesting food, for circulating fluids through the body, and for oxydating those fluids. In vertebral animals these organs consist of stomachs, to which an alimentary canal is attached; a heart which is alternately contracted and expanded, to which a set of arteries and veins are attached-the former for conveying the fluids from the heart, and the latter for returning them to the heart; lungs or gills in which the same fluids are presented to the oxygen of the atmosphere. Some animals have their fluids oxydated by means of spiracles or breathing holes, some by means of exterior membranous organs.

GRAND DIVISIONS. The subjects of Zoology are distributed into four grand divisions; because animals appear to have been organized upon four general plans.

I. Vertebral Animals. In this division the sentient principle is lodged in a medullary substance, the basis of which is inclosed in a bony tube, composed of a column of vertebra.

To the nervous axis inclosed in a bony tube, which is called the medulla spinalis, there is an appendage at one extremity denominated the brain. This is inclosed in a bony case, called the cranium or skull. But animals of this division have another system of nerves, more analagous to the systems found in the other three divisions than the medulla spinalis. It is that system which extends through the heart, lungs and

stomach, and is connected with the brain by a very minute fibre. Nature seems to have been very solicitous to provide for the digestive, respiratory and circulatory systems, in every division of animals. The system of nerves, devoted to this object, is kept almost distinct in vertebral animals, and the medulla spinalis, as well as the brain, seem to be but appendages.

The organs of sense and motion are all double, and are arranged on two sides of the nervous axis. To the vertebral column are attached two series of ribs, constituting the chief frame-work of the body. Strong bony limbs are bound to each extremity of the bony column, which are mostly covered by the muscles which give them motion. The viscera that are the most essential to life, are inclosed in the head and spine.

Both brain and medulla spinalis being peculiar to this division, the sentient principle is much more perfect in this than in the other divisions. Here we find four pair of organs of sense. Two eyes, two ears, two nostrils, and two fleshy masses constituting a tongue, or rather a pair of organs of taste.

These animals have red blood, hearts with alternate motions of contraction and dilatation, horizontal jaws adapted to the preparation of food for the digestive process. They are viviparous or oviparous, and from the commencement of their lives till death, they supply the daily waste of their bodies by masticating and passing into the stomach, aliment suited to their respective natures. A part of this aliment is carried into the circulatory system by lymphatic vessels.

Animals of this division being more complicated in their structure, are subject to a greater variety of diseases. They have more acute pains and more exquisite pleasures.

Examples. Man, bat, squirrel, elephant, deer, whale, eagle, humming-bird, tortoise, crocodile, viper, frog, eel, shark, salmon.

II. Articulated Animals.-In this division the sentient principle is lodged in two long cords, swelling at intervals into knots or ganglions, extended through a jointed body in the longitudinal direction. The organs of sense and motion are all double, and arranged on two sides of the nervous axis.

The principle ganglion is placed near the throat. They have jointed trunks or abdomens; and all but one class, have jointed limbs articulated to an external crust or to a rigid covering. They draw in their food through suckers or tubes, serving as mouths, in most cases. Air vessels, through which respiration is performed, open on the sides of their bodies or limbs.