RELATION AND DISTRIBUTION OF PLANT AND ANIMAL LIFE
Life in the world is represented by the Vegetable and Animal kingdoms. Plants and animals, unlike minerals, grow from germs, and develop into individuals with definite forms and organs. After a limited existence they die, their species being perpetuated by seed or offspring. The functions of plants and animals in nature are, however, entirely unlike. Plants are rooted in the soil; animals are free to move over the land, through the water or air. The plant, moreover, transforms the lifeless, inorganic elements (earth and air) into organic matter and thus prepares food for the animal. In its quiet, steady growth it gathers a store of force which the animal uses up in action. Thus the distribution of vegetation regulates that of animal life. Besides, vegetation clothes the surface of the land with that rich mantle of verdure and flowers which is its greatest ornament.
All living things are termed organisms, and the science which takes account of them with special regard to their common characteristics is termed Biology, or Life-lore. The classification and life-history of plants are the objects of that part of biology known as Botany. That part similarly occupied with the study of animals is known as Zoology.
Throughout the entire realm of nature, in the animal world as well as in the vegetable, the development of life increases in energy, and in the variety and perfection of the types, with the increasing intensity of light and heat, from the poles to the equator.
TROPICAL LIFE
Within the tropics, under the stimulating rays of a vertical Sun, grow the most dense and varied forests, the most expanded foliage, and the largest and the most brilliant flowers. Here, also, are found the most delicious fruits, the most powerful aromatics, the greatest variety of plants capable of affording sustenance to man, and the largest number of those which contribute to the luxuries of civilized life.
In the tropical regions, also, are found the greatest variety of land animals; with the highest types, the greatest stature, the most intense activity, and the keenest intelligence exhibited in the brute creation.
WHERE THE MOST POWERFUL
ANIMALS ARE FOUND
This zone is the home of the gigantic elephant and giraffe; of the lion and the tiger, the most powerful of all the beasts of prey; and of the gorilla, chimpanzee, and ourang-outang, of all animals most resembling men.
Here, also, are the ostrich, the largest and most powerful of birds; the condor, surpassing in size all other birds of flight; and the humming-birds of South America, the smallest of the feathered tribes, unsurpassed in brilliancy of coloring, rapidity of motion, and grace of form.
In the same zone are those enormous reptiles, the crocodile and the boa-constrictor, with the hooded snakes and other serpents of most deadly venom; and insects of all sizes in indescribable profusion.
LIFE IN THE TEMPERATE ZONES
In the Warm-Temperate Zone, though the Sun never reaches the zenith, yet during the long summer his rays are almost vertical; while the winter is so mild that snow and ice are of rare occurrence.
Here the vegetable world is less prodigal in species, and less luxuriant in growth, than in the tropical regions; still, verdure is continuous throughout the year, and fruits and flowers succeed each other almost without interruption.
The animal world shows a similar, though less marked, decrease in the exuberance of life. The higher orders are less numerous, the individuals less gigantic and powerful; yet the antelopes, among the most graceful of animals, and the camel, one of the most useful, especially characterize this zone.
HOW THE LIFE OF THE TEMPERATE ZONE
DIFFERS FROM THAT OF WARMER ZONES
In the Temperate Zone, farther from the tropics, and receiving the Sun’s rays with greater obliquity, all the forms of vegetable growth are more modest than in the preceding. The forests are less dense and varied, the foliage is less luxuriant, and flowers of brilliant hues are confined to shrubs and herbaceous plants.
Though useful plants are numerous, yet scarce a species is of value in its spontaneous growth; and, above all, the long dormant season, when the trees and shrubs are bare and apparently lifeless, stamps the vegetation of this zone with an aspect of inferiority.
The animal world still shows a large number of noble species; yet there are some orders which, like the plants, are dormant during the winter; while many of the birds migrate to warmer climes. Associated with deciduous forests, boundless fertile prairies, and arid steppes—are the bear, the wolf, the lynx, the bison, and many species of elk and deer.
ORIGINAL HOME OF OUR
DOMESTIC ANIMALS
Here is the home of the horse, the ass, and many varieties of oxen, sheep, and goats,—those animals which, domesticated by man, have accompanied him to all climes, adapting themselves to all circumstances. The American turkey, the European pheasant, and the Asiatic parents of many of our domestic fowls, also belong to the temperate zone; together with a multitude of song birds, whose sober plumage, contrasting so gloomily with the brilliant colors of their neighbors of the tropics, is compensated by the sweetness of their notes. Here, also, is the home of the honey-bee, and of the silk-worm, almost the only insects directly useful to man.
LIFE IN THE COLD ZONES
In these regions, where the sun is always low, and in winter is above the horizon but a small part of the time, all nature becomes increasingly monotonous. The conifers, with their stiff forms and sombre hues, impart a dreary aspect even to the summer landscape; and, during the long winter, all life seems suspended.
The animal world, however, is more rich and varied than the vegetable.
Here we meet the great moose and the brown bear, the beaver and other rodents, in large numbers; the sable, the mink, the ermine, and a host of other animals whose fine, soft furs form one of the main resources of this inhospitable clime.
In the Arctic Zone—where the forests give place to dwarf trees, stunted or creeping shrubs, mosses, and lichens—the reindeer, the musk-ox, and the white bear are the only representatives of the larger land animals, though the smaller furry tribes are still numerous.
The sea, however, more genial in its temperature than the land, swarms with living creatures of innumerable species, among which are the largest representatives of the animal kingdom. The whale, the walrus, and the seal, inhabit the Arctic seas; with every grade of marine life, down to the animalculæ, which are so numerous as to give their color to great areas of sea-water; and water-fowl, without number, and of many varieties, enlivens the icy shores.