The Beauties of Nature, and the Wonders of the World We Live In. Sir John Lubbock

There is no species of animal or plant which would not well repay, I will not say merely the study of a day, but even the devotion of a lifetime. Their form and structure, development and habits, geographical distribution, relation to other living beings, and past history, constitute an inexhaustible study.

When we consider how much we owe to the Dog, Man's faithful friend, to the noble Horse, the patient Ox, the Cow, the Sheep, and our other domestic animals, we cannot be too grateful to them; and if we cannot, like some ancient nations, actually worship them, we have perhaps fallen into the other extreme, underrate the sacredness of animal life, and treat them too much like mere machines.

Some species, however, are no doubt more interesting than others, especially perhaps those which live together in true communities, and which offer so many traits—some sad, some comical, and all interesting—which reproduce more or less closely the circumstances of our own life.

The modes of animal life are almost infinitely diversified; some live on land, some in water; of those which are aquatic some dwell in rivers, some in lakes or pools, some on the sea-shore, others in the depths of the ocean. Some burrow in the ground, some find their home in the air. Some live in the Arctic regions, some in the burning deserts; one little beetle (Hydrobius) in the thermal waters of Hammam-Meskoutin, at a temperature of 130°. As to food, some are carnivorous and wage open war; some, more insidious, attack their victims from within; others feed on vegetable food, on leaves or wood, on seeds or fruits; in fact, there is scarcely an animal or vegetable substance which is not the special and favourite food of one or more species. Hence to adapt them to these various requirements we find the utmost differences of form and size and structure. Even the same individual often goes through great changes.

GROWTH AND METAMORPHOSES

The development, indeed, of an animal from birth to maturity is no mere question of growth. The metamorphoses of Insects have long excited the wonder and admiration of all lovers of nature. They depend to a great extent on the fact that the little creatures quit the egg at an early stage of development, and lead a different life, so that the external forces acting on them, are very different from those by which they are affected when they arrive at maturity. A remarkable case is that of certain Beetles which are parasitic on Solitary Bees. The young larva is very active, with six strong legs. It conceals itself in some flower, and when the Bee comes in search of honey, leaps upon her, but is so minute as not to be perceived. The Bee constructs her cell, stores it with honey, and lays her egg. At that moment the little larva quits the Bee and jumps on to the egg, which she proceeds gradually to devour. Having finished the egg, she attacks the honey; but under these circumstances the activity which was at first so necessary has become useless; the legs which did such good service are no longer required; and the active slim larva changes into a white fleshy grub, which floats comfortably in the honey with its mouth just below the surface.

Even in the same group we may find great differences. For instance, in the family of Insects to which Bees and Wasps belong, some have grub larvæ, such as the Bee and Ant; some have larvæ like caterpillars, such as the Sawflies; and there is a group of minute forms the larvæ of which live inside the eggs of other insects, and present very remarkable and abnormal forms.

These differences depend mainly on the mode of life and the character of the food.

RUDIMENTARY ORGANS

Such modifications may be called adaptive, but there are others of a different origin that have reference to the changes which the race has passed through in bygone ages. In fact the great majority of animals do go through metamorphoses (many of them as remarkable, though not so familiar as those of insects), but in many cases they are passed through within the egg and thus escape popular observation. Naturalists who accept the theory of evolution, consider that the development of each individual represents to a certain extent that which the species has itself gone through in the lapse of ages; that every individual contains within itself, so to say, a history of the race. Thus the rudimentary teeth of Cows, Sheep, Whales, etc. (which never emerge from their sockets), the rudimentary toes of many mammals, the hind legs of Whales and of the Boa-constrictor, which are imbedded in the flesh, the rudimentary collar-bone of the Dog, etc., are indications of descent from ancestors in which these organs were fully developed. Again, though used for such different purposes, the paddle of a Whale, the leg of a Horse and of a Mole, the wing of a Bird or a Bat, and the arm of a Man, are all constructed on the same model, include corresponding bones, and are similarly arranged. The long neck of the Giraffe, and the short one of the Whale (if neck it can be called), contain the same number of vertebræ.

Even after birth the young of allied species resemble one another much more than the mature forms. The stripes on the young Lion, the spots on the young Blackbird, are well-known cases; and we find the same law prevalent among the lower animals, as, for instance, among Insects and Crustacea. The Lobster, Crab, Shrimp, and Barnacle are very unlike when full grown, but in their young stages go through essentially similar metamorphoses.

No animal is perhaps in this respect more interesting than the Horse.

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