It is not many years since Mr Ward first drew the attention of botanists to the cultivation of plants in closely-glazed cases; but the most sanguine dreams of the discoverer could not then have foretold the many useful purposes to which the Wardian Case has become applicable, nor the important influence which it was destined to obtain in promoting the pleasant pursuits of gardening and botany. The Wardian Case has been instrumental in diffusing a love of these pursuits among all classes of society. It has opened up to those whose pursuits confine them within the limits of the city's smoke-cloud, a means whereby they may obtain 'a peep at nature, if they can no more.' Far removed from green fields and leafy woods, they may, for instance, enjoy their leisure mornings in watching one of the most beautiful phenomena of vegetable development—the evolution of the circinate fronds of the fern; a plant in every respect associated with elegance and beauty. This kind of gardening has, therefore, become of late years one of the most fashionable, while at the same time one of the most pleasant sources of domestic amusement.
An interesting companion to the Wardian Case has lately been presented in the Aquatic Plant Case, or Parlour Aquarium, due to the ingenuity of Mr Warington, and which has for its object, as its name indicates, the cultivation of aquatic or water plants. It may be described as a combination of the Wardian Case and the gold-fish globe, the object being to illustrate the mutual dependence of animal and vegetable life. Mr Warington has lately detailed his experiments. 'The small gold-fish were placed in a glass-receiver of about twelve gallons' capacity, having a cover of thin muslin stretched over a stout copper wire, bent into a circle, placed over its mouth, so as to exclude as much as possible the sooty dust of the London atmosphere, without, at the same time, impeding the free passage of the atmospheric air. This receiver was about half-filled with ordinary spring-water, and supplied at the bottom with sand and mud, together with loose stones of limestone tufa from Matlock, and of sandstone: these were arranged so that the fish could get below.... A small plant of Vallisneria spiralis was introduced, its roots being inserted in the mud and sand, and covered by one of the loose stones, so as to retain the plant in its position.... The materials being thus arranged, all appeared to go on well for a short time, until circumstances occurred which indicated that another and very material agent was required to perfect the adjustment.' The decaying leaves of the vallisneria produced a slime which began to affect the fish injuriously: this it was necessary to get quit of. Mr Warington introduced five or six snails (Limnea stagnalis), 'which soon removed the nuisance, and restored the fish to a healthy state; thus perfecting the balance between the animal and vegetable inhabitants, and enabling both to perform their functions with health and energy. So luxuriant was the growth of the vallisneria under these circumstances, that by the autumn the one solitary plant originally introduced had thrown out very numerous offshoots and suckers, thus multiplying to the extent of upwards of thirty-five strong plants, and these threw up their long spiral flower-stems in all directions, so that at one time more than forty blossoms were counted lying on the surface of the water. The fish have been lively, bright in colour, and appear very healthy; and the snails also—judging from the enormous quantities of gelatinous masses of eggs which they have deposited on all parts of the receiver, as well as on the fragments of stone—appear to thrive wonderfully, affording a large quantity of food to the fish in the form of the young snails, which are devoured as soon as they exhibit signs of vitality and locomotion, and before their shell has become hardened.'
In remarking upon the result of his experiments, Mr Warington observes: 'Thus we have that admirable balance sustained between the animal and vegetable kingdoms, and that in a liquid element. The fish, in its respiration, consumes the oxygen held in solution by the water as atmospheric air, furnishes carbonic acid, feeds on the insects and young snails, and excretes material well adapted as a rich food to the plant, and well fitted for its luxuriant growth. The plant, by its respiration, consumes the carbonic acid produced by the fish, appropriating the carbon to the construction of its tissues and fibres, and liberates the oxygen in its gaseous state to sustain the healthy functions of the animal life; at the same time that it feeds on the rejected matter, which has fulfilled its purposes in the nourishment of the fish and snail, and preserves the water constantly in a clean and healthy condition. While the slimy snail, finding its proper nutriment in the decomposing vegetable matter and minute confervoid growth, prevents their accumulation by removing them; and by its vital powers converts what would otherwise act as a poison into a rich and fruitful nutriment, again to constitute a pabulum for the vegetable growth, while it also acts the important part of a purveyor to its finny neighbours.'[5] This perfect adjustment in the economy of the animal and vegetable kingdoms, whereby the vital functions of each are permanently maintained, is one of the most beautiful phenomena of organic nature.
The Parlour Aquarium affords valuable, we might say invaluable, facilities to the naturalist in the prosecution of his researches. The botanist can now conveniently watch the development of aquatic plants under conditions not unnatural, throughout the entire period of their existence, from their germination to the production of flowers and the perfection of seeds; and we are in hopes that much of the obscurity that invests many aquatic vegetables will in consequence be cleared up. The zoologist is perhaps even more indebted to the invention. The habits, not only of the fishes, but of the mollusca, can be accurately studied under natural conditions, and many important facts of their history ascertained and illustrated. The water-beetles and other aquatic insects will also come in for a share of attention.
In concluding his paper in the Garden Companion (i. p. 7), Mr Warington states, that he is at present attempting a similar arrangement with a confined portion of sea-water, employing some of the green sea-weeds as the vegetable members of the circle, and the common winkle or whelk to represent the water-snails. In a Report of the Yorkshire Naturalist's Club, November 5, 1851,[6] we observe it stated, that Mr Charlesworth read an extract from a letter from a gentleman in America, detailing some successful experiments on keeping marine molluscs alive in sea-water for months; but our inquiries have not been successful in eliciting any further information on the subject.
Experiments of our own have led to the conclusion, that some families of aquatic plants are altogether unsuitable for the Parlour Aquarium—such as, potamogeton, chara, &c., which very soon communicate a putrescent odour to the water in which they are grown, rendering it highly disagreeable in a sitting-room.
FOOTNOTES:
[5] Quarterly Journal of the Chemical Society, iii, 52.
[6] Naturalist, vol. i. 239.