THE AQUARIUM.
The successful treatment of aquatic plants and animals, in the confined
space of a glass Aquarium, depends entirely upon the discovery that
there exists in Nature a self-adjusting balance between the supply of
oxygen created in water, with the quantity consumed by aquatic animals.
And it became equally necessary to know the means by which that supply
was continually generated. Without the knowledge of these facts, and the
principles by which they are regulated, it would have been impossible to
establish such a marine Aquarium as that we may now any day examine in
the Regent’s Park; where, in a few glass tanks of very moderate size, we
may see examples of some of the most curious forms of animal and
vegetable life peculiar to the depths of the ocean—forms so singular,
that their first exhibition created a sense of wonder little less
intense than that which must have been caused, long years ago, by the
first public display of the mountain form of the elephant to the people
of cold northern countries; and much more so than the recent
introduction of the giraffe or hippopotamus, although they have never
been seen in Europe since the days of the Romans.
Those principles, the knowledge of which was requisite to enable us thus
to view the wonders of the ocean in their living state in an Aquarium,
were not mastered at once, or by one man, or in one generation. The
nature of certain relations between animal and vegetable life, upon
which they are founded, was first advanced by Priestley, towards the
close of the last century, who proved that plants give forth the oxygen
necessary to animal life. The learned Ingenhauss, a native of Breda, but
who principally resided in England, defined this principle still more
clearly, in a work the title of which pretty fully explains the entire
nature of his discovery. It was published in French, at Leyden, in 1778,
and in London, in English, in 1779. The French edition is before me, the
title of which I translate, “Experiments upon Plants, which prove their
important influence in the purification of the atmospheric air when they
are exposed to the rays of the sun, and the contrary results which ensue
when they are placed in the shade, or during the night.” The action of
the sun’s rays in disengaging the oxygen generated in plants is thus
clearly announced, and the knowledge of this principle is one of those
which have mainly conduced, as I have said, to the successful
establishment of Aquaria.
In the course of his essay Ingenhauss states, still more directly, that
plants “immersed in water,” when exposed to the action of light, emit an
air which he announces as oxygen gas; and this idea is the key-stone of
the Aquarium.
But, although the discovery of Ingenhauss at once rendered the thing
practicable, Aquaria did not then come into fashion. The science of
natural history was not at that time sufficiently advanced; for the
specimens, even in public museums, were merely heterogeneous
collections, assembled without the slightest regard to classification,
or any other useful purpose. A stuffed cat with nine legs, stood,
perhaps, next to a bottled snake, followed by the skin of a crocodile,
to be succeeded in turn by a very moth-eaten specimen of a King Charles
spaniel, “supposed, upon good authority, to have belonged to Nell
Gwynne.” A few scores of such objects, with the addition of an ostrich
egg and a few sea-shells, without any attempt at name or description,
formed a very respectable museum in those times; and we may, therefore,
easily conceive that (in so far as experiments illustrative of natural
science were concerned) the suggestions of Ingenhauss remained tolerably
dormant.
It was not till the year 1833, that Professor Daubeny communicated, to
the British Association at Cambridge, a paper concerning some new
researches prosecuted in the same direction; and not till 1837, that Mr.
Ward became the first to apply the principle to any purpose analogous to
that of the Aquarium. In that year he made a report to the British
Association, on the hermetically closed glass cases in which he had
succeeded in growing many classes of plants, and keeping them in a
healthy state without any fresh supply of air. He stated, at the same
time, his belief that certain classes of animals would live and thrive
under similar circumstances. This was the first direct hint towards the
formation of a closed Vivarium, whether atmospheric or aquatic.
In 1842, Dr. Johnston satisfactorily proved the true vegetable nature of
_Corallines_ by observing their growth in a vessel containing sea-water;
and thus was established the first true Aquarium. With the experimental
tuft of _Coralline_ was a small frond of a green _Ulva_, and numerous
_Rissoæ_, &c., and several _Annelids_ afterwards appeared, having been,
no doubt, attached to the branches of the _Coralline_, or the fronds of
the _Ulva_. At the end of four weeks the water was still pure, the
Molluscs and other animals alive, and the Confervæ grown; the
_Coralline_ having thrown out several additional articulations. After
eight weeks, the water still remained sweet. But had any animal, of even
the lowest order, been so confined, without the accompanying presence of
vegetables giving off oxygen, all of that vital gas contained in so
small a quantity of water would have been quickly exhausted, and the
water would have become corrupt, ammoniacal, and poisonous to the life
of any living thing. But the author of this experiment had not in view
the testing of the possibility of preserving the forms of ocean life in
a healthy state in confinement; his business had been to settle an
important point connected with the classification of the _Corallines_;
and having successfully decided that question, the embryo Aquarium was
abandoned.
On the 4th of June, 1850, Mr. R. Warrington communicated to the Chemical
Society a series of observations on the adjustment of certain relations
between the animal and vegetable kingdoms, very important to our present
purpose. Two small gold-fish were placed in a glass receiver, a small
plant of _Valisneria spiralis_ being planted at the same time in some
earth, beneath a layer of sand in the same vessel. All went on well by
this arrangement, without any necessity for changing the water; the
oxygen given off by the plant proving itself sufficient for the supply
of its animal co-tenants, and the water therefore remaining clean and
pure, until some decaying leaves of the _Valisneria_ caused turbidity,
and confervoid growth began to accumulate on the sides of the vessel. To
remedy this evil, Mr. Warrington brought to bear the results of previous
observations on water in natural ponds under analogous circumstances;
and, guided by these observations and their results, he placed a few
common pond-snails in the vessel containing his gold-fish and plant of
_Valisneria_.
The new inmates, immediately upon their introduction, began to feed
greedily upon the decaying vegetable matter, and all was quickly
restored to a healthy state. They proved, indeed, of still further
advantage, for the masses of eggs which they deposited evidently
presented a kind of food natural to the fishes, which was eagerly
devoured by them, so that the snails became not only the scavengers, but
also the feeders of the little colony. And so this first of true Aquaria
prospered; the animals and plants proving of mutual value and support to
each other. The snails disposed of the decaying leaves, which would have
tainted the water and rendered it unfit for the healthy existence of the
plant, and the plant in turn gave forth, under the rays of sunlight, the
supply of oxygen necessary to both fish and snails.
In January, 1852, Mr. Warrington, commenced a series of similar
experiments with sea-water; which were, at first, not so satisfactory,
but in the end proved as entirely successful. In the course of his
experiments, he found the red and brown _Algæ_, or sea-weed, less proper
for the formation of oxygen than the green. Of the latter class he
procured specimens of _Enteromorpha_ and _Ulva latissima_, which he
chiselled from the rocks about Broadstairs, along with the pieces of
chalk or flint to which they were attached; and, when he placed them in
his own marine Aquarium, he put in along with them, to represent the
pond-snails in the fresh-water tank, some of the common sea-snail,
better known as the Periwinkle (_Littorina littorea_). But these proved,
it appears, insufficient for the destruction of the mucous and
gelatinous matter that arose from the decay of the red sea-weeds, which,
however, I have no doubt may yet be cultivated with equal success with
the green, as I shall state when describing them. Under the existing
difficulty, Mr. Warrington found it necessary to aerate the water by
other means, many processes being equally available; such as injecting
fresh-water from a syringe, or establishing a drip, of some height, from
a vessel containing a supply of entirely fresh-water. Mr. Warrington
also discovered, in the course of these experiments, the necessity that
the light should pass directly through the surface of the water to the
plants, as in natural ponds and seas—a very important step in the
successful management of Aquaria; and he therefore had a slab of slate
adjusted to the side of his tank which stood next to the light.
These successful experiments, both in fresh-water and marine Aquaria,
assign to Mr. Warrington, beyond dispute, the credit of being the
originator, or inventor, if the term may be so used, of these charming
additions to our conservatories, corridors, and even living-rooms, to
which they are certainly a much more attractive and instructive addition
than the old globe of blank water, with its pair of gold-fish swimming
round and round in ceaseless gyrations, tiresome to behold, in the vain
hope of escaping from their glaring and inconvenient prison; in which
they would inevitably have perished very shortly but for the daily
change of water, which, previous to our knowledge of air-emitting plants
and their use, was absolutely necessary.
But another experimentalist was now in the field. Mr. Gosse, whose
charming works upon Aquaria and other subjects connected with natural
science, have, perhaps, made his name more widely known than that of his
predecessor, Mr. Warrington, commenced a series of experiments on the
subject of the marine Aquarium, about the same time as the last-named
gentleman, in the beginning of January, 1852. His experiments were
crowned with such complete success that he was induced to put himself in
communication with Mr. David Mitchell, the enterprising Secretary of the
Zoological Society, the result of which was the removal of the
collection of _Annelids_ and _Zoöphytes_ which Mr. Gosse had formed, to
the gardens of the Society in the Regent’s Park; where it formed the
nucleus from which has grown the magnificent series of Aquaria in the
building constructed specially for their reception. These marine Aquaria
at once became a subject of public as well as private interest, and the
Aquarium house was so crowded daily with its curious visitors, that it
was difficult to get a glimpse of the wonders of the “ocean floor,” and
its zoöphytic denizens, which were so successfully exhibited there;
principally through the skilful aid and untiring industry of Mr. Gosse,
through whose hands above five thousand specimens passed at the time,
collected at the request of the Zoological Society.
In his interesting record of his early essays, Mr. Gosse gives us many
valuable particulars concerning his successive experiments, and the
various disappointments to which he was at first subjected; many of them
from causes now too well understood to require repetition. His principal
difficulty arose from over-crowding, although his tank did not appear,
as he states, too much filled. Another disappointment was caused by
putting in animals before the smell of the putty, with which the glass
sides were fixed, had sufficiently gone off.
Mr. Gosse’s tank was made with a slate bottom, and birch pillars, in
which were grooves to receive the glass; and its dimensions were, two
feet long by one foot six wide, the depth not being mentioned.
Taking these dimensions into consideration, it will be easy to conceive,
when the following list of specimens which Mr. Gosse introduced into his
Aquarium is examined, that his population was too dense for the extent
of his province, although the space might not have appeared too much
filled for picturesque effect. Of vegetable specimens, he introduced at
once the following:—
1. A tuft of _Furcellaria fastigiata_.
2. Two of _Rhodymenia palmata_.
3. One of _Dictyota dichotoma_.
4. A small _Fucus serratus_.
5. One _Laminaria digitata_.
6. Two tufts of _Padina pavonia_.
7. Several masses of _Corallina officinalis_.
8. _Griffithsia setacea._
9. _Delesseria alata._
10. _Plocamium coccineum._
11. _Phylophora rubens._
12. _Zostera marina._
In a few days the water, poured carefully to these specimens, became
clear as pale green crystal, the green tinge being too slight to obscure
the colour of any object seen through its medium.
From these weeds alone, before any supply of Zoöphytes or Molluscs were
intentionally added, a whole host of minute animal life swarmed forth;
some, doubtless, issuing from eggs newly hatched; others from the
shelter of the matted ramifications of some of the sea-weeds, in which
they had been taken, as in a net. Among these swarming creatures were
Annelids of the genus _Syllis_, _Rissoæ_, and other minute shell-fish,
but principally _Isopodous_ and _Entomostracous Crustacea_, many of them
being so minute as not to be perceived without the use of a powerful
lens.
Of the animals next placed in this tank, of only two feet by one foot
six inches, the following is the list given:—
FISH.
1. Fifteen, Spined Stickleback _Gasterosteus spinachia_.
2. Seven, Gray Mullet (young) _Mugil capito_.
3. One, Black Goby _Gobious niger_.
4. One, Corkwing _Crenilabrus cornubicus_.
5. One, Five-bearded Rockling _Motella 5-cirrata_.
6. One, Great Pipe-fish (young) _Syngnathus acus_.
7. One, Worm Pipe _Syngnathus lumbriformis_.
SHELLS, MOLLUSCS, ETC.
1. Two, Ashy Top _Trochus cinerarius_.
2. One, Navel Top _Trochus umbilicatus_.
3. Three, Common Periwinkle _Littorina littorea_.
4. Three, Yellow Periwinkle _Littorina littoralis_.
5. One, Purple _Purpura lapillus_.
6. One, Scrobicularia.
7. One, Anomia.
8. Two, Common Cockle _Cardium edule_.
9. Two, Ascidia.
CRUSTACEA, ETC.
1. Two, Hermit Crab _Pagurus Bernhardus_.
2. One, ditto _Pagurus Prideauxii_.
3. Four, Sand Shrimp _Cragnon vulgaris_.
4. One, Prawn _Palæmon serratus_.
5. Three, Crown Worm _Serpula triquetra_.
6. Three, White-line Worm _Nereis bilineata_.
ZOÖPHYTES.
1. Two, Thick-horned Anemone _Actinia crassicornis_.
2. Three, Weymouth Anemone _Actinia clavata_.
3. Two, Parasitic Anemone _Actinia parasitica_.
4. Six, Plumose Anemone _Actinia dianthus_.
5. Five, Daisy Anemone _Actinia bellis_.
There were thus above seventy specimens, animal and vegetable, already
in the tank, without counting the swarms of smaller creatures, some the
young of large species, daily increasing in size; yet, our bold
experimentalist, anxious to conquer his “Russia” at one grand invasion,
still poured in fresh specimens. These consisted of:—
FISH.
1. One, Æquorial Pipe-fish _Syngnathus æquoreus_.
MOLLUSCS, CRUSTACEANS, ETC.
1. One, Rough Doris _Doris pilosa_.
2. Two, Magus Top _Trochus magus_.
3. One, Nerit _Natica Alderi_.
4. One, Squin _Pecten opercularis_.
5. One, Pholas _Pholas parvæ_.
6. One, Pisa _Pisa tetraodon_.
7. One, Cleanser Crab _Portunus depurator_.
8. One, Ebalia _Ebalia Pennantii_.
9. One, Hermit (small) _Pagurus . . . . . ._
10. Three, Lobster Prawn _Athanas nilescens_.
STAR-FISH, ETC.
1. One, Brittle Star _Ophiocoma rosula_.
2. One, Eyed Cribella _Cribella oculata_.
3. Two, Scarlet Sun-Star _Solaster papposa_.
4. One Bird’s-foot Star _Palmipes membranaceus_.
5. Three, Gibbons Starlet _Asterina gibbosa_.
6. One, Purple-tipped Urchin _Echinus miliaris_.
7. Seven, Scarlet Madrepore _Balanophillia regia_.
8. Three, Cloak Anemone _Adamsia palliata_.
These additions brought the collection up to above a hundred specimens,
and no doubt the tank made a glorious show; but Mr. Gosse, though the
Napoleon of his specialty, was forced to acknowledge that there was an
“impossible.” Although his collection was superb, and his interesting
tank did not look over-crowded, yet he soon discovered that a forbidden
limit had been passed, and that the creatures of the ocean that have
yards—fathoms—of their native element to their own separate share,
cannot accommodate themselves to the allotment system, in the proportion
of a square inch to each individual.
To remedy this state of things, the evil effects of which soon became
apparent, artificial aeration was resorted to, by means of another
vessel, which kept up a continuous supply of dripping fresh water. But
even this assistance did not enable the crowded colony to exist more
than ten days. In the first place, there were many predatory species,
which destroyed their associates; these kinds must, therefore, be
excluded from an Aquarium, or kept in a separate tank. But, after all,
the impossibility of providing a sufficient supply of oxygen was
evidently the great and principal cause of failure. The Univalves and
smaller Crustacea disappeared first, a disagreeable smell giving
intimation that decay was going on, the creatures that had perished
having, many of them, died in concealment, under the stones, weeds, &c.,
at the bottom of the Aquarium. The first signs of unpleasant effluvia
rising from the tank must, therefore, be carefully attended to; and, in
such cases, the Aquarium ought to be immediately searched for the cause;
which, when discovered, should be immediately removed.
[Illustration: PLATE XI.
A DESIGN FOR A PLAINLY-MOUNTED AQUARIUM.]
Mr. Gosse having taken out the whole of the specimens, dead and alive,
and carefully cleansed the tank, a much smaller number was put in,
which, being well selected, and having sufficient space, throve
abundantly well; and the ingenious experimentalist was at last amply
rewarded for all his persevering exertions. This result benefited others
as well as himself, for a general taste suddenly arose for this kind of
pursuit, among all who read the various works which soon appeared on the
subject; and, to gratify the new taste, a host of dealers in Aquaria
have sprung up, who are driving a brisk and profitable trade.
The first experiments of Mr. Gosse sufficiently point out the kind of
cautions to be observed in the formation of a marine Aquarium. The
vessel itself may be either quite plain in its frame-work, as shown in
Plate XI., or made more or less ornamental, to assimilate, if necessary,
with surrounding objects or furniture. The rustic style of frame,
designed in Plate XII., has been found to accord well with the general
character of the Aquarium itself, and it produces an agreeable contrast
with the usual forms of the furniture of our ordinary sitting-rooms.
[Illustration: PLATE XII.
A DESIGN FOR AN AQUARIUM MOUNTED IN HANDSOME RUSTIC-WORK.]
Those made by the dealers are generally formed with slate floors and
backs, and zinc columns and mountings; the smallest and most simple,
about fifteen inches long by ten inches broad, costing from a guinea to
twenty-five shillings, and those of the proportion of two feet by one
foot six costing from two pounds ten to three pounds. A small syphon
will be useful, in order to remove a portion of the water, if required,
without disturbance; and also a syringe, in order to aerate the water
when necessary, if a second reservoir of fresh-water, in a suitable
position, should not be convenient. A miniature landing-net is also
useful for the removal of decaying matter, or occasionally the living
specimens when any change may be required.
A layer of sand and pebbles, about three inches deep, placed upon the
slate flooring, is the first step towards arranging the interior of the
tank. Upon this beginning, removing the sand and stones in places to
procure a firm basis, the rock-work may be built; which should be
picturesque and fanciful in character, as partially suggested in the two
Plates, leaving miniature archways and caves for the shelter of such
creatures as shun the light, either constantly or occasionally. Such a
disposition of the rock imparts, at the same time, many pleasing effects
to the pictorial composition. These matters are not, however, much
attended to by dealers, whose arrangements of the Aquaria they offer for
sale are generally tasteless enough. But that is perhaps all the better,
as it entails upon the amateur the necessity of providing his own taste,
which is at all times both a useful and pleasant effort of mind, and
which, moreover, leaves, after each period of exertion, a permanent
trace of an increased refinement which influences the whole character.
In the distribution of the rocks, I would always allow at least one
point to project above the water, in order to afford the opportunity to
those animals whose instincts lead them to seek occasional exposure to
the air, the means of gratifying it by that contrivance. I have thought,
indeed, of constructing a kind of double Aquarium, and perfecting a
contrivance by means of which a large portion of water should flow
gradually from one tank to the other at fixed periods, in imitation of
the ebb and flow of the tide. Many interesting phenomena would be
exhibited in this manner, such as the closing of the _Actiniæ_ as the
water receded, and their expansion as it covered them on its return.
This alternation, too, might be found highly advantageous to the health
and development of the animals whose natural habitat lies between high
and low water-mark, and whose constitution is therefore framed to
require entire or partial exposure to the air at certain intervals of
time. I also prefer, as preserving a similar set of analogies, a sloping
bottom, similar to that of the coast. For instance, if the slate back of
the Aquarium be placed next the light, which is its proper position, as
the light ought to penetrate the water entirely through its upper or
horizontal surface, then I would fill the side next the slate back
nearly to the top with pieces of rock, gradually reducing their height,
till, at the other side, they should hardly rise above the floor of sand
and pebbles, leaving, at last, a flat portion of the pebbly or sandy
bottom quite level.
When this form of rock-work is decided upon, the Aquarium should be of
rather wider proportions than usual, in order to allow of the slope
being pretty gradual. Supposing the tank to fill entirely the recess of
a spare window, which is a position in which it looks exceedingly well,
a solid slate back may be found to darken the vessel or the room too
much; in such a case, a glass back must be preferred, which can be
shaded from the direct influence of the light by a blue or green shade
of calico neatly fitted to the frame; and it must be borne in mind, as
essential, that the Aquarium must be so placed as to receive the direct
rays of light during some part of the day, being screened by a white
blind when the sun may be too powerful; as should the water become
_tepid_, it would be fatal to many of the inhabitants of the miniature
sea.
With due observance of these precautions, the amateur may hope to frame
and establish an Aquarium in a suitable form, and in a suitable position
for the reception of its inmates; an account of which, and of the manner
of their introduction, will form the subject of the ensuing chapters.
[Illustration]
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