There is yet another very important chain of circumstances which binds these two great kingdoms together. This is the chain of the animal necessities. A large number of races feed directly upon vegetables; herbs and fruits are the only things from which they gain those elements required to restore the waste of their systems.
These herbivorous animals, which must necessarily form fat and muscle from the elements of their vegetable diet, are preyed on by the carnivorous races; and from these the carbon is again restored to the vegetable world. Sweep off from the earth the food of the herbivora, they must necessarily very soon perish, and with their dissolution, the destruction of the carnivora is certainly ensured. To illustrate this on a small scale, it may be mentioned that around the coasts of Cornwall, pilchards were formerly caught in very great abundance, in the shallow water within coves, where these fish are now but rarely seen. From the investigations of the Messrs. Couch, whose very accurate observations on the Cornish fauna have placed both father and son amongst the most eminent of British naturalists,[224] it appears that the absence of these fish is to be attributed entirely to the practice of the farmers, who cut the sea-weed from the rocks for the purpose of manuring their lands. By this they destroy all the small crustacea inhabiting these immature marine forests feeding on the algæ, and as these, the principal food of the pilchards, have perished they seek for a substitute in more favourable situations. Mr. Darwin remarks, that if the immense sea-weeds of the Southern Ocean were removed by any cause, the whole fauna of these seas would be changed.
We have seen that animals and vegetables are composed principally of four elementary principles,—oxygen, hydrogen, nitrogen, and carbon. We have examined the remarkable manner in which they pass from one condition—from one kingdom of nature—into another. The animal, perishing and dwindling by decomposition into the most simple forms of matter, mingling with the atmosphere as mere gas, gradually becomes part of the growing plant, and by like changes vegetable organism progresses onward to form a portion of the animal structure.
A plant exposed to the action of natural or artificial decomposition passes into air, leaving but a few grains of solid matter behind it. An animal, in like manner, is gradually resolved into “thin air.” Muscle, and blood, and bones, having undergone the change, are found to have escaped as gases, leaving only “a pinch of dust,” which belongs to the more stable mineral world. Our dependency on the atmosphere is therefore evident. We derive our substance from it—we are, after death, resolved again into it. We are really but fleeting shadows. Animal and vegetable forms are little more than consolidated masses of the atmosphere. The sublime creations of the most gifted bard cannot rival the beauty of this, the highest and the truest poetry of science. Man has divined such changes by the unaided powers of reason, arguing from the phenomena which science reveals in unceasing action around him. The Grecian sage’s doubts of his own identity, were only an extension of a great truth beyond the limits of our reason. Romance and superstition resolve the spiritual man into a visible form of extreme ethereality in the spectral creations, “clothed in their own horror,” by which their reigns have been perpetuated.
When Shakespeare made his charming Ariel sing—
“Full fathom five thy father lies,
Of his bones are coral made,
Those are pearls that were his eyes:
Nothing of him that doth fade,