But to what purpose should I begin anew? Would there not be the same failure? What had been wrong?
At least two great faults were evident. First, in order to guard against the possibility of a leak, the bottom and posts of the tank had been covered with many coats of an alcoholic varnish. Now it was probable that time enough had not elapsed between the several applications for the thorough evaporation of the alcohol. Might not its gradual infusion in the water have caused the death of the animalcula in such numbers as to taint the whole by their decay?
The second fault was, strewing upon the surface of the sand a handful or two of white powdered quartz, which, from having been pulverized in an iron mortar, was so oxydized as to turn a deep yellow. This might have poisoned the animalcula.
The first fault seemed to me the chief, but I proceeded to remedy both. The whole contents of the tank being removed, it was thoroughly washed on the inside, exposed for several days to the sun and air, and then soaked for twelve hours in clean sea-water. This being thrown away, the stones, scalded and well-washed, were restored, and clean sand, replaced the old.
Water was drawn from the dock at high tide; but it was less clear now, on the fourth of June, than that which had been got early in May. This surprised me not a little; for, as I stood upon the wharf and looked down into it just before sunset on the previous evening, I was struck with its beautiful limpidity. Curious to see if its aspect remained unaltered, I went to the same spot where I had stood the night before. The tide was at the same height, but twelve hours had made a marvellous change in the appearance of the water. Its sparkling clearness had given way to greenness and turbidity, and no object could be seen a foot below the surface. No storm had stirred its depths during the night,—why this change? Conjecture was of no practical utility, and I returned home satisfied that my fifteen gallons of water were as clear as any it was then in my power to obtain. Covering the tub from the dust, I left it to settle until sunset. Then the ever-useful siphon drew off two thirds of it tolerably clear, leaving a thick green deposit upon the sides and bottom of the vessel. Next day, it was again drawn off from the sediment, (at this time, small in quantity,) and poured into the tank. Several newly obtained plants of well-growing Enteromorpha and Corallina were arranged among the stones, and the Aquarium was left at rest. Gradually the water became nearly clear, but not perfectly so until after the introduction of animals.
Eight days after it was filled, the Actinias were put in; on the ninth, several small Mollusks; on the tenth, Crustacea; and on the eleventh and twelfth, other varieties of the same types; but not until the fourteenth day were fishes ventured upon.
Day by day the water grew clearer and clearer, until, at the end of three weeks, it was beautifully translucent. Three more weeks passed, during which the beauty of the Aquarium was much heightened by a luxuriant growth of Confervae mingled with Enteromorpha, which together covered all those parts of the stones which received a direct light. The mimic rocks seemed draped in green velvet, and in the sunlight were studded with pearly bubbles. There was, however, one blemish: the hungry crabs had so nibbled the larger plants that it was deemed necessary to renew them, in order to secure a sufficient supply of food and oxygen. Accordingly, a fine specimen of Enteromorpha was added. It consisted of five or six delicate fronds about five inches in length, and these soon increased to treble their original number and twice their original size. At the end of about two weeks, they suddenly became covered with a dull bluish mould, at the same time ceasing to give out bubbles; and the whole plant, instead of rising to the surface of the water as hitherto, hung limp from the fissure where it was placed, and trailed upon the sand. Coincidently, (was it consequently?) a greenish tinge pervaded the water, speedily increasing in depth and opacity. In five days, no object could be discerned six inches from the glass, and my beautiful Aquarium was transformed to an unsightly ditch.
Yet the water was apparently pure, and the activity of its inhabitants was in no wise lessened. What was this vexatious greenness? Was it animal or vegetable? Was it the diffused spores of the perfected Enteromorpha or of the rank Confervae upon the stones? If neither, what was its cause?
Excess of light was the most obvious suggestion; and so it was supposed that its exclusion might be a potent remedy. Therefore a double curtain of glazed muslin was stretched across the window; and the tank, both top and sides, wrapped in folds of paper. A week of darkness changed the deep green to a dingy olive. But the experiment could not be continued. The nightly admission of air by lifting the paper covering was insufficient to maintain the imprisoned creatures. They were happy, though captive, while in a mimic ocean, but miserable in a dark dungeon. Languid and spiritless, they lay supine, or crawled listlessly and aimlessly about. This would not do, and so light was again admitted freely to all but one side of the tank; there, a screen of yellow paper intercepted the direct rays of the sun, while upon the top they fell through the foliage of a Clematis vine.
Three weeks more wrought a slight change for the better; but it was too slight and too slow for my patience, or that of curious friends waiting to see my Aquarium.