with which the next are painted, and we live—man and brute—on the débris of the past.
I see all this and more in the aquarium; it teaches me lessons in physics, and, I trust, also teaches me that the moral and spiritual truths of the universe may be illustrated, sometimes explained, by a patient study of the commonest things. The aquarium is a world in little; it sustains itself. For the moment, I put aside the law of gravity as a universal law, and the presence of the atmosphere as a universal thing, and I call it a world, needing no aid, for its continuance and the perfect adjustment of its balance of power, from external things. I take a vessel of glass, a few pebbles, a few pieces of sandstone-rock, and a sufficiency of water, and to that I commit my fishes and insects, and say, "There is your world; the order of Nature is such that you may henceforth live and die without human interference." I say nothing here of the details of management; I am looking for instruction in the laws of life and death.
The two requisites of animal life, food and air, must be generated in this world, or it ceases to instruct me; yet the water contains but little of each, and whence is its supply to come? God has ordained such a wealth of organic forms that, wherever the conditions of life are found, life takes possession of the spot, whether it be the bottom of the ocean, the dripping roof of a cave, the expanse of the viewless air, or the mimic lake I call an aquarium. Forthwith the dead stones become alive with greenness, the glass walls assume the semblance of a meadow, the milky hue of the water disappears as the earthy particles it held in solution subside, and the light that streams through it takes a tint of greenness. There is an order of vegetation appointed to occupy such sites, and almost every non-metallic, and some metallic substances too, become speedily coated with conferva?, when their surfaces are kept moist a sufficient length of time. Were it not so, the inhabitants of my world must perish; and to prove the fact I try an experiment. I place some fishes in a clean vessel of water, without pebbles and without rock; the moment the first dim bronzy speck appears, I rub it off the glass, and so thwart the course of Nature. The fishes soon exhaust the water of its oxygen, and though the water attempts to renew its supplies by absorption from the atmosphere, the compensation is too slow, the fishes come gasping to the surface, and in a short while perish.
Even then I learn something from their death if I leave the vessel in the hands of Nature. Death has no sooner spread his black banner over my household gods than life of another kind arises to confound him, and the microscope reveals to me myriads of animals and plants, and organisms that seemingly occupy an intermediate place between the two great kingdoms, rioting upon the wreck that death has made. My half-dozen dead fishes have given birth to existences numerous as the stars in heaven, or as the sand upon the sea-shore, innumerable.
