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his aquarium. Many of them we have either grown ourselves, or seen growing under conditions similar to

Fig. 45.

Bur Reed (Sparganium ramosum).

those described. At the same time we have ventured to hint that such selections might be made as would

convert the aquarium, if the tank be large enough, into an aquatic garden as well. No British plants have such a fragile hot-house look as our aquatic species, and they would therefore suit the life of indoors admirably, and be the means of contributing another element to the many surroundings which already make our English homes the happiest on the earth!

BRYANT'S "THANATOPSIS.”

97

CHAPTER VII.

MOLLUSCA, INSECTS, ETC., OF THE FRESH-WATER AQUARIUM.

THE solitary naturalist in his search after the manifold living forms of life soon feels, as William Cullen Bryant says in "Thanatopsis," that

"To him who in the love of nature holds

Communion with her visible forms, she speaks

A various language."

The

It is a language which gives forth no uncertain sound; and, although the mystery of earthly life starts forth even more vividly when the student discovers the hourly carnage by which it can alone be sustained, this does not detract from an unshaken confidence in the wisdom and even love of the Almighty Power that superintends it! Mere earthly life is not the highest thing in the universe. carelessness with which myriads are crushed, and even their types are lost, proclaims it to none more clearly than to the naturalist. We see these things but as in a glass darkly, yet we obtain a glimpse of the important fact that the life-scheme of our globe, past and present, is one and indivisible, and that the individual members of it which perish and give place

H

to others, have no more right to complain than the blood-corpuscles of our body, when they are spent in energy and replaced by those newly formed!

The aquarium keeper soon finds that it is necessary to be constantly replenishing his stock. Not only has he first to get something like a balance of animal and vegetable life, he has also to see that the associated animals do not breed too fast or too slowly. If the former, then he introduces one or two species which keep them down by preying upon them; if the latter, he adds additional specimens. If all the animals of his aquaria be carnivorous and none herbivorous, his tank will soon be converted into a regular field of battle, and war will be the order of the day, until the combatants are reduced to the fabled condition of the Kilkenny cats. He has, therefore to copy nature in this respect, and mind that his aquatic pets are taken from the carnivorous and herbivorous classes alike, and that they are placed in such a relation to each other that the marvellous fecundation of the herbivorous group replaces the ravages made upon them by the carnivorous. It is evident that if the herbivorous kinds are in the ascendant, harm will soon issue to the balance of life by the oxygen-yielding plants being devoured. Hence the importance of having both carnivorous and herbivorous creatures in the same tank if possible.

We have dwelt at some length upon the commoner

LIMNEAS.

Fig. 46.

99

fresh-water fishes and amphibians with which the ordinary aquarium may be stocked; and now briefly refer to other species not belonging to these orders, which are equally common in all our ponds and tarns, and equally interesting and animated when transferred to the aquarium. First of all we may notice those commoner species of water snails, whose hardiness and voracity prove of great service in keeping down the impalpable green alga, which will develop even in the best managed aquarium. Of these none are more abundant than the Limnacea, and of the eight British species included in the order, perhaps the best is Limnea stagnalis. It will crawl over the inner surface of the glass, and keep it as clean as if well dusted. Occasionally it may be seen floating, and then before it descends to the bottom of the tank, it utters a perceptible sound, caused by disengaging the air from its pouch, which had kept it buoyant. species is the handsomest we

[graphic]

This

Lymnea stagnalis.

have, and the young shells are especially graceful and slender. Limnea auricularia is a much smaller shell, with a larger body-whorl, the outer lip of which is reflected. Although not so common as L. stag

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