The sumptuous abode of Licinius Crassus echoes with his sighs and
groans. His children and slaves respect his profound sorrow, and leave
him with intelligent affection to solitude,--that friend of great grief,
so grateful to the afflicted soul, because tears can flow unwitnessed.
Alas! the favorite sea-eel of Crassus is dead, and it is uncertain
whether Crassus can survive it!
This sensitive Roman caused his beloved fish to be buried with great
magnificence: he raised a monument to its memory, and never ceased to
mourn for it. So say Macrobius and Aelian.
This man, we are told, who displayed so little tenderness towards his
servants, had an extraordinary weakness concerning his fine sea-eels. He
passed his life beside the superb fish-pond, where he lovingly
fattened them from his own hand. Nor was his fondness for pisciculture
exceptional in his times. The fish-pond, to raise and breed the
finest varieties of fish, was as necessary an adjunct to a complete
establishment as a barn-yard or hen-coop to a modern farmer or rural
gentleman. Wherever there was a well-appointed Roman villa, it contained
a _piscina_; while many gardens near the sea could boast also a
_vivarium_, which, in this connection, means an oyster-bed.
Fish-ponds, of course, varied with the wealth, the ingenuity, and the
taste of their owners. Many were of vast size and of heterogeneous
contents. The costly _Muraena_, the carp, the turbot, and many other
varieties, sported at will in the great inclosures prepared for them.
The greater part of the Roman emperors were very fond of sea-eels.
The greedy Vitellius, growing tired of this dish, would at last, as
Suetonius assures us, eat only the soft roe; and numerous vessels
ploughed the seas in order to obtain it for him. The family of Licinius
took their surname of Muraena from these fish, in order thus to
perpetuate their silly affection for them. The love of fish became a
real mania, and the _Murcena Helena_ was worshipped.
Hortensius, who possessed three splendid country-seats, constructed in
the grounds of his villa at Bauli a fish-tank so massive that it has
endured to the present day, and so vast as to gain for it even then the
name of _Piscina Mircihilis_. It is a subterraneous edifice, vaulted,
and divided by four rows of arcades and numerous columns,--some ten
feet deep, and of very great extent. Here the largest fishes could be
fattened at will; and even the mighty sturgeon, prince of good-cheer,
might find ample accommodations.
Lucullus, that most ostentatious of patricians, and autocrat of
_bons-vivants_, had a mountain cut through in the neighborhood of
Naples, so as to open a canal, and bring up the sea and its fishes to
the centre of the gardens of his sumptuous villa. So Cicero well names
him one of the Tritons of fish-pools. His country-seat of Pausilypum
resembled a village rather than a villa, and, if of less extent, was
more magnificent in luxury than the gigantic villa of Hadrian, near
Tivoli. Great masses of stone-work are still visible, glimmering under
the blue water, where the marble walls repelled the waves, and ran out
in long arcades and corridors far into the sea. Inlets and creeks,
which wear even now an artificial air, mark the site of _piscinae_ and
refreshing lakes. Here were courts, baths, porticoes, and terraces, in
the _villa urbana_, or residence of the lord,--the _villa rustica_ for
the steward and slaves,--the _gallinarium_ for hens,--the _apiarium_ for
bees,--the _suile_ for swine,--the _villa fructuaria_, including the
buildings for storing corn, wine, oil, and fruits,--the _horius_, or
garden,--and the park, containing the fish-pond and the _vivarium_.
Statues, groves, and fountains, pleasure-boats, baths, jesters, and even
a small theatre, served to vary the amusements of the lovely grounds and
of the tempting sea.
But it was not to be supposed that men satiated with the brutal shows
of the amphitheatre, even if enervated by their frequentation of the
Suburra, could, on leaving the city, be always content with simple
pleasures, rural occupations, or pleasure-sails. Habit demanded
something more exciting; and the ready tragedy of a fish-pond filled
with ravenous eels fed upon human flesh furnished the needed excitement.
For men _blasé_ with the spectacles of lions and tigers lacerating the
_bestiarii_. It was much more exciting to witness a swarm of sea-eels
tearing to pieces an awkward or rebellious slave. Vedius Pollio, a Roman
knight of the highest distinction, could find nothing better to do for
his dear Muraenae than to throw them slaves alive; and he never
failed to have sea-eels served to him after their odious repast, says
Tertullian. It is true, these wretched creatures generally deserved this
terrible punishment; for instance, Seneca speaks of one who had the
awkwardness to break a crystal vase while waiting at supper on the
irascible Pollio.
Pisciculture was carried so far that fish-ponds were constructed on
the roofs of houses. More practical persons conducted a stream of
river-water through their dining-rooms, so that the fish swam under the
table, and it "was only necessary to stoop and pick them out the moment
before eating them; and as they were often cooked on the table, their
perfect freshness was thus insured. Martial (Lib. X., Epigram. XXX., vv.
16-25) alludes to this custom, as well as to the culture and taming of
fish in the _piscina_.
"Nec seta largo quaerit in mari praedam,
Sed e cubiclo lectuloque jactatam
Spectatus alte lineam trahit piscis.
Si quando Nereus sentit Aeoli regnum,
Ridet procellas tula de suo mensa.
Piscina rhombum pascit et lupos vernas,
Nomenculator mugilem citat notum
Et adesse jussi prodeunt senes mulli."
It having been remarked that the red mullet passed through many changes
of color in dying, like the dolphin, fashion decreed that it should die
upon the table. Served alive, inclosed in a glass vessel, it was cooked
in the presence of the attentive guests, by a slow fire, in order
that they might gloat upon its sufferings and expiring hues, before
satisfying their appetites with its flesh.
It will not surprise us to learn that the eminent _gourmand_ Apicius
offered a prize to the inventor of a new sauce made of mullets' livers.
But we may remark, that fish, like all other natural objects, were
studied by the ancients only to pet or to eat. All their views of
Nature were essentially selfish; none were disinterested, reverential,
deductive, or scientific. Nature ministered only to their appetites,
in her various kinds of food,--to their service, in her beasts of
burden,--or to their childish or ferocious amusement, with talking
birds, as the starling, with pet fish, or with pugnacious wild beasts.
There was no higher thought. The Greeks, though fond of flowers, and
employing them for a multitude of adornments and festive occasions
entirely unequalled now, yet did not advance to their botanical study or
classification. The Roman, if enamored of the fine arts, could see no
Art in Nature. There was no experiment, no discovery, and but little
observation. The whole science of Natural History, which has assumed
such magnitude and influence in our times, was then almost entirely
neglected.
And yet what an opportunity there was for the naturalist, had a single
enthusiast arisen? All lands, all climes, and all their natural
productions were subservient to the will of the Emperor. The orb of the
earth was searched for the roe of eels or the fins of mullets to gratify
Caesar. And the whole world might have been explored, and specimens
deposited in one gigantic museum in the Eternal City, at the nod of a
single individual. But the observer, the lover of Nature, was wanting;
and the whole world was ransacked merely to consign its living tenants
to the _vivaria_, and thence to the fatal arena of the amphitheatre. Yet
even here the naturalist might have pursued his studies on individuals,
and even whole species, both living and dead, without quitting Rome. The
animal kingdom lay tributary at his feet, but served only to satiate his
appetite or his passions, and not to enrich his mind.
So, again, Rome's armies traversed the globe, and her legions were often
explorers of hitherto unknown regions. But no men of science, no corps
of _savans_ was attached to her cohorts, to march in the footsteps
of conquest and gather the fruits of victory to enrich the schools.
Provinces were devastated, great cities plundered, nations made captive,
and all the masterpieces of Art borne off to adorn Rome. But Nature was
never rifled of her secrets; nor was discovery carried beyond the most
material things. The military spirit stifled natural science.
There were then, to be sure, no tendencies of thought to anything but
war, pleasure, literature, or art. There was comparatively no knowledge
of the physical sciences, whose culture Mr. Buckle has shown to have
exerted so powerful an influence on civilization. The convex lens--as
since developed into the microscope, the giver of a new world to
man--was known to Archimedes only as an instrument to burn the enemy's
fleet.
* * * * *
Modern pisciculture in some measure imitates, although, it does not
rival the ancient. Many methods have been devised in France and England
of breeding and nurturing the salmon, the trout, and other valuable
fish, which are annually becoming more scarce in all civilized
countries. But all this is on a far different principle from that
pursued at Rome. We follow pisciculture from necessity or economy,
because fish of certain kinds are yearly dying out, and to produce
a cheap food; but the Romans followed it as a luxury, or a childish
amusement, alone. And although our aldermen may sigh over a missing
Chelonian, as Crassus for his deceased eel, or the first salmon of the
season bring a fabulous price in the market, yet the time has long
passed when the gratification of appetite is alone thought of in
connection with Nature. We know that living creatures are to be studied,
as well as eaten; and that the faithful and reverent observation of
their idiosyncrasies, lives, and habits is as healthful and pleasing to
the mind as the consumption of their flesh is wholesome and grateful
to the body. The whole science of Zoölogy has arisen, with its simple
classifications and its vast details. The _vivaria_ of the Jardin des
Plantes rival those of the Colosseum in magnitude, and excel them in
object. Nature is ransacked, explored, and hunted down in every field,
only that she may add to the general knowledge. Museums collect and
arrange all the types of creative wisdom, from the simple cell to man.
Science searches out their extinct species and fossil remains, and tells
their age by Geology. The microscope pursues organic matter down into an
infinity of smallness, proportionately as far as the telescope traces it
upwards in the infinity of illimitable space. Last of all, though not
till long after the earth and the air had been seemingly exhausted,
the desire of knowledge began to push its way into the arcana of the
sea,--that hidden half of Nature, where are to be found those wonders
described by Milton at the Creation,--where, in obedience to the Divine
command,
"Be fruitful, multiply, and in the seas
And lakes and running streams the waters fill, ...
Forthwith the sounds and seas, each creek and bay,
With fry innumerable swarm, and shoals
Of fish, that with their fins and shining scales
Glide under the green wave in sculls that oft
Bank the mid sea: part single or with mate
Graze the sea-weed, their pasture, and through groves
Of coral stray, or sporting with quick glance
Show to the sun their waved coats dropt with gold,
Or in their pearly shells at ease attend
Moist nutriment, or under rocks their food
In jointed armor watch."
But no means were at hand to pursue these unknown creatures to their
unknown residences, and to observe their manners when at home. Single,
withered, and often mutilated specimens of minute fish, mollusks, or
radiata, in the museum, alone illustrated the mysteries of the deep sea.
Fish, to be sure, could be kept for longer or shorter periods in globes
of glass filled with water; but the more delicate creatures inevitably
perished soon after their removal from their mysterious abodes. Such
a passionate desire to "search Nature and know her secrets" finally
originated the idea of the Aquarium.
The term _vivarium_ was used among the ancients to signify many
things,--from the dens of the wild animals which opened under the
Colosseum, to an oyster-bed; and so now it may mean any collection of
living creatures. Hence it could convey no distinct idea of a marine
collection such as we propose to describe. The term _aqua_ was added to
express the watery element; but the compound _aqua-vivarium_ was too
clumsy for frequent employment, and the abbreviated word _aquarium_ has
come into general use.
Thus the real Aquarium is a water-garden and a menagerie combined,--and
aims to show life beneath the waters, both animal and vegetable, in
all the domestic security of its native home, and in all the beauty,
harmony, and nice adaptation of Nature herself. It is no sudden
discovery, but the growth of a long and patient research by naturalists.
"What happens, when we put half a dozen gold-fish into a globe? The
fishes gulp in water and expel it at the gills. As it passes through the
gills, whatever free oxygen the water contains is absorbed, and carbonic
acid given off in its place; and in course of time, the free oxygen of
the water is exhausted, the water becomes stale, and at last poisonous,
from excess of carbonic acid. If the water is not changed, the fishes
come to the surface and gulp atmospheric air. But though they naturally
breathe air (oxygen) as we do, yet they are formed to extract it from
the water; and when compelled to take air from the surface, the gills,
or lungs, soon get inflamed, and death at last puts an end to their
sufferings.
"Now, if a fish-globe be not overcrowded with fishes, we have only
to throw in a goodly handful of some water-weed,--such as the
_Callitriche_, for instance,--and a new set of chemical operations
commences at once, and it becomes unnecessary to change the water. The
reason of this is easily explained. Plants absorb oxygen as animals
do; but they also absorb carbonic acid, and from the carbonic add thus
absorbed they remove the pure carbon, and convert it into vegetable
tissue, giving out the free oxygen either to the water or the air, as
the case may be. Hence, in a vessel containing water-plants in a state
of healthy growth, the plants exhale more oxygen than they absorb, and
thus replace that which the fishes require for maintaining healthy
respiration. Any one who will observe the plants in an aquarium, when
the sun shines through the tank, will see the leaves studded with bright
beads, some of them sending up continuous streams of minute bubbles.
These beads and bubbles are pure oxygen, which the plants distil from
the water itself, in order to obtain its hydrogen, and from carbonic
acid, in order to obtain its carbon."[A]
[Footnote A:_The Book of the Aquarium_, by Sidney Hibbert.]
Thus the water, if the due proportion of its animal and vegetable
tenants be observed, need never be changed. This is the true Aquarium,
which aims to imitate the balance of Nature. By this balance the whole
organic world is kept living and healthy. For animals are dependent upon
the vegetable kingdom not only for all their food, but also for
the purification of the air, which they all breathe, either in the
atmosphere or in the water. The divine simplicity of this stupendous
scheme may well challenge our admiration. Each living thing, animal or
plant, uses what the other rejects, and gives back to the air what the
other needs. The balance must be perfect, or all life would expire, and
vanish from the earth.
This is the balance which we imitate in the Aquarium. It is the whole
law of life, the whole scheme of Nature, the whole equilibrium of our
organic world, inclosed in a bottle.
For the rapid evolution of oxygen by plants the action of sunlight is
required. That evolution becomes very feeble, or ceases entirely, in the
darkness of the night. Some authorities assert even that carbonic acid
is given off during the latter period. So, too, they claim that there
are two distinct processes carried on by the leaves of plants,--namely,
respiration and digestion: that the first is analogous to the same
process in animals; and that by it oxygen is absorbed from, and carbonic
acid returned to the atmosphere, though to a limited degree: and that
digestion consists in _the decomposition of carbonic acid by the green
tissues of the leaves under the stimulus of the light, the fixation of
solid carbon, and the evolution of pure oxygen_. The theory of distinct
respiration has been somewhat doubted by the highest botanical authority
of this country; but the theory of digestion is indisputable. And it is
no less certain that all forms of vegetation give to the air much more
free oxygen than they take from it, and much less carbonic acid, as
their carbonaceous composition shows. If fresh leaves are placed in
a bell-glass containing air charged with seven or eight per cent. of
carbonic acid, and exposed to the light of the sun, it will be found
that a large proportion of the carbonic acid will have disappeared, and
will be replaced by pure oxygen. But this change will not be effected in
the dark, nor by any degree of artificial light. Under water the oxygen
evolved from healthy vegetation can be readily collected as it rises, as
has been repeatedly proved.
Why carbonic acid is, to a limited degree, given off by the plant in the
night, is merely because the vital process, or the fixation of carbon
and evolution of oxygen, ceases when the light is withdrawn. The plant
is only in a passive state. Ordinary chemical forces resume their sway,
and the oxygen of the air combines with the newly deposited carbon to
reproduce a little carbonic acid. But this must be placed to the account
of decomposing, not of growing vegetation; for by so much as plants
grow, they decompose carbonic acid and give its oxygen to the air, or,
in other words, purify the air.
It has been found by experiment, that every six pounds of carbon in
existing plants has withdrawn twenty-two pounds of carbonic acid gas
from the atmosphere, and replaced it with sixteen pounds of oxygen gas,
occupying the same bulk. And when we consider the amount of carbon that
is contained in the tissues of living, and of extinct vegetation also,
in the form of peat and coal, we may have some idea of the vast body of
oxygen which the vegetable kingdom has added to the atmosphere.
And it is also to be considered, that this is the only means we know of
whereby free oxygen is given to supply the quantity constantly consumed
in respiration, combustion, and other vast and endless oxygen-using
processes. It follows, therefore, that animals are dependent upon plants
for their pure oxygen, as well as for their food. But the vegetable
kingdom might exist independently of the animal; since plants may derive
enough carbon from the soil, enriched by the decaying members of their
own race.
There is, however, one exception to the law that plants increase the
amount of oxygen in the air. During flowering and fruiting, the stores
of carbon laid up in the plant are used to support the process, and,
combining with the oxygen of the air, both carbonic acid and heat are
given off. This has been frequently proved. In large tropical plants,
where an immense number of blossoms are crowded together, the
temperature has risen twenty to fifty degrees above that of the
surrounding air.
As most of the aquatic plants are cryptogamous, or producing by spores,
and not by flowers, it seems probable that the evolution of carbonic
acid and heat is much less in degree in them, and therefore less in the
water than in the air. We may, therefore, venture to lay it down as a
general principle, that plants evolve free oxygen in water, when in
the sunlight, and remove the carbonic acid added to the water by the
respiration of the animals.
But since this is a digestive or nutritive process, it follows that
aquatic plants may derive much or all of their food from the water
itself, or the carbon in it, in the same manner as the so-called
air-plant, which grows without soil, does from the air. It is true, at
any rate, that, in the fresh-water aquarium, the river and brook plants
need no soil but pebbles; and that the marine plants have no proper
root, but are attached by a sort of sucker or foot-stalk to stones and
masses of rock. It is very easy to see, then, how the aquarium may
be made entirely self-supporting; and that, excepting for the larger
carnivorous fish, who exhaust in a longer or shorter period the minute
creatures on which they live, no external food is required.
A very simple experiment will prove the theory and practicability of the
aquarium. In a glass jar of moderate size was placed a piece of _Ulva
latissima_, or Sea-Lettuce, a broad-leaved, green, aquatic plant, and a
small fish. The mouth was closed by a ground glass stopper. The jar was
exposed to the light daily; the water was never changed; nor was the
glass stopper removed, excepting to feed the fish, once or twice a week,
with small fragments of meat. At the end of eight months both remained
flourishing: the fish was lively and active; and the plant had more than
half filled the bottle with fresh green leaves.
Any vessel that will hold water can, of course, be readily converted
into an aquarium. But as we desire a clear view of the contents at all
times, glass is the best material. And since glass globes refract the
light irregularly and magnify and distort whatever is within them, we
shall find an advantage in having the sides of the aquarium parallel and
the form rectangular. As the weight of the aquarium, when filled with
water, is enormous,--far more than we should at first imagine,--it
follows that it must be capable of resisting pressure both from above
and from within. The floor and stand, the frame and joints must be
strong and compact, and the walls of plate or thick crown glass. The
bottom should be of slate; and if it is designed to attach arches of
rock-work inside to the ends, they, too, must be of slate, as cement
will not stick to glass. The frame should be iron, zinc, or well-turned
wood; the joints closed with white-lead putty; the front and back of
glass. There is one objection to having the side which faces the light
of transparent glass, and that is that it transmits too much glare of
sunlight for the health of the animals. In Nature's aquarium the light
enters only from above; and the fish and delicate creatures have always,
even then, the shady fronds of aquatic plants or the shelter of the
rocks,--as well as the power of seeking greater depths of water, where
the light is less,--to protect themselves from too intense a sunshine.
It is, therefore, sometimes advisable to have the window side of the
aquarium made of glass stained of a green color. It is desirable that
all aquarial tanks should have a movable glass cover to protect them
from dust, impure gases, and smoke.
When we speak of an aquarium, we mean a vessel holding from eight to
thirty gallons of water. Mr. Gosse describes his larger tank as being
two feet long by eighteen inches wide and eighteen inches deep, and
holding some twenty gallons. Smaller and very pretty tanks may be
made fifteen inches long by twelve inches wide and twelve deep. Great
varieties in form and elegance may be adapted to various situations.
There are two kinds of aquaria, the fresh- and the salt-water: the one
fitted for the plants and animals of ponds and rivers; the other for the
less known tenants of the sea. They are best described as the River and
the Marine Aquarium, and they differ somewhat from each other. We shall
speak first of the fresh-water aquarium.
The tank being prepared, and well-seasoned, by being kept several weeks
alternately full and empty, and exposed to the sun and air, so that all
paint, oil, varnish, tannin, etc., may be wholly removed, the next thing
is to arrange the bottom and to plant it. Some rough fragments of rock,
free from iron or other metals that stain the water, may be built into
an arch with cement, or piled up in any shape to suit the fancy. The
bottom should be composed entirely of shingle or small pebbles, well
washed. Common silver sand, washed until the water can be poured through
it quite clear, is also suitable.
Mould, or soil adapted to ordinary vegetation, is not necessary to
the aquatic plants, and is, moreover, worse than useless; since it
necessitates the frequent changing of the water for some time, in order
to get rid of the soluble vegetable matter, and promotes the growth of
Confervae, and other low forms of vegetation, which are obnoxious.
Aquatic plants of all kinds have been found to root freely and flourish
in pebbles alone, if their roots be covered. The plants should be
carefully cleared of all dead parts; the roots attached to a small
stone, or laid on the bottom and covered with a layer of pebbles and
sand.
The bottom being planted, the water may be introduced through a
watering-pot, or poured against the side of the tank, so as to avoid any
violent agitation of the bottom. The water should be pure and bright.
River-water is best; spring-water will do, but must be softened by the
plants for some days before the fishes are put in.
Sunshine is good for the tank at all seasons of the year. The
fresh- requires more than the salt-water aquarium. The amount of
oxygen given off by the plants, and hence their growth and the
sprightliness of the fishes, are very much increased while the sun
is shining on them.
In selecting plants for the aquarium some regard is to be paid to the
amount of oxygen they will evolve, and to their hardiness, as well as to
their beauty. When it is desired to introduce the fishes without waiting
long for the plants to get settled and to have given off a good supply
of oxygen, there is no plant more useful than the _Callitricke_, or
Brook Star-wort. It is necessary to get a good supply, and pick off the
green heads, with four or six inches only of stem; wash them clean,
and throw them into the tank, without planting. They spread over the
surface, forming a rich green ceiling, grow freely, and last for months.
They are continually throwing out new roots and shoots, and create
abundance of oxygen. Whenever desired, they can be got rid of by simply
lifting them out.
The _Vallisneria_, or Tape-Grass, common in all our ponds, is essential
to every fresh-water tank. It must be grown as a bottom-plant, and
flourishes only when rooted. The _Nitella_ is another pleasing variety.
The _Ranunculus aquatilis_, or Water-Crowfoot, is to be found in almost
every pond in bloom by the middle of May, and continues so into the
autumn. It is of the buttercup family, and may be known as a white
buttercup with a yellow centre. The floating leaves are fleshy; the
lower ones finely cut. It must be very carefully washed, and planted
from a good joint, allowing length enough of stem to reach the surface.
Some of the blossom-heads may also be sprinkled over the surface, where
they will live and bloom all through the summer. The _Hydrocharis_,
or Frog's-Bit, and the _Alisma_, or Water-Plantain, are also easily
obtained, hardy and useful, as well as pleasing. Many rarer and more
showy varieties may be cultivated; we have given only the most common
and essential. All the varieties of _Chara_ are interesting to the
microscopist, as showing the phenomenon of the circulation of the sap,
or Cyclosis.
Of the living tenants of the aquarium, those most interesting, as well
as of the highest organization, are the fishes. And among fishes, the
family of the _Cyprinidae_ are the best adapted to our purpose; for we
must select those which are both hardy and tamable. _Cyprinus gibelio_,
the Prussian Carp, is one of the best. It will survive, even if the
water should accidentally become almost exhausted of oxygen. It may
be taught, also, to feed from the hand. None of the carp are very
carnivorous. _Cyprinus auratus_, or the Gold-fish, is one of the most
ornamental objects in an aquarium. But the Minnow, _C. phoxinus_, is the
jolliest little fish in the tank. He is the life of the collection, and
will survive the severest trials of heat and cold. The Chub, a common
tenant of our ponds, is also a good subject for domestication. The
Tench and Loach are very interesting, but also very delicate. Among the
spiny-finned fishes, the Sticklebacks are the prettiest, but so savage
that they often occasion much mischief. For a vessel containing
twelve gallons the following selection of live stock is among those
recommended: Three Gold Carp, three Prussian Carp, two Perch, four
large Loach, a dozen Minnows, six Bleak, and two dozen Planorbis. Some
varieties of the Water-Beetles, or Water-Spiders, which the fishes
do not eat, may also well be added. The Newt, too, is attractive and
harmless.
All may go on well, and the water remain clear; but after the tank has
been established several weeks, the inner sides of the glass will show a
green tinge, which soon increases and interferes with the view. This is
owing to the growth of a minute confervoid vegetation, which must be
kept down. For this purpose the Snail is the natural remedy, being the
ready scavenger of all such nuisances. Snails cling to the sides, and
clean away and consume all this vegetable growth. The _Lymnea_ is among
the most efficient, but unfortunately is destructive, by eating holes
in the young fronds of the larger plants, and thus injuring their
appearance. To this objection some other varieties of snail are not
open. The _Paludina_ and _Planorbis_ are the only kinds which are
trustworthy. The former is a handsome snail, with a bronze-tinted,
globular shell; the latter has a spiral form. These will readily reduce
the vegetation. And to preserve the crystal clearness of the water, some
Mussels may be allowed to burrow in the sand, where they will perform
the office of animated filters. They strain off matters held in
suspension in the water, by means of their siphons and ciliated gills.
With these precautions, a well-balanced tank will long retain all the
pristine purity of Nature.
Specimens for the river aquarium may be readily obtained in almost
any brook or pool, by means of the hand-net or dredge. It will be
astonishing to see the variety of objects brought up by a successful
haul. Small fish, newts, tadpoles, mollusks, water-beetles, worms,
spiders, and spawn of all kinds will be visible to the naked eye; while
the microscope will bring out thousands more of the most beautiful
objects.
A very different style of appearance and of objects distinguishes the
Salt-water or Marine Aquarium.
As the greater part of the most curious live stock of the salt-water
aquarium live upon or near the bottom, so the marine tank should be more
shallow, and allow an uninterrupted view from above. Marine creatures
are more delicately constituted than fresh-water ones; and they demand
more care, patience, and oversight to render the marine aquarium
successful.
Sea-sand and pebbles, washed clean, form the best bottom for the
salt-water aquarium. It must be recollected that many of the marine
tenants are burrowers, and require a bottom adapted to their habits.
Some rock-work is considered essential to afford a grateful shelter and
concealment to such creatures as are timid by nature, and require a spot
in which to hide: this is true of many fishes. Branches of coral, bedded
in cement, may be introduced, and form beautiful and natural objects, on
which plants will climb and droop gracefully.
Sea-water dipped from the open sea, away from the mouths of rivers,
is, of course, the best for the marine aquarium. If pure, it will bear
transportation and loss of time before being put into the tank. It may,
however, not always be possible to get sea-water, particularly for the
aquarium remote from the seaboard, and it is therefore fortunate that
artificial sea-water will answer every purpose.
The composition of natural sea-water is, in a thousand parts,
approximately, as follows: Water, 964 parts; Common Salt, 27; Chloride
of Magnesium, 3.6; Chloride of Potassium, 0.7; Sulphate of Magnesia,
(Epsom Salts,) 2; Sulphate of Lime, 1.4; Bromide of Magnesium, Carbonate
of Lime, etc., .02 to .03 parts. Now the Bromide of Magnesium, and
Sulphate and Carbonate of Lime, occur in such small quantities, that
they can be safely omitted in making artificial seawater; and besides,
river and spring water always contain a considerable proportion of lime.
Therefore, according to Mr. Gosse, we may use the following formula: In
every hundred parts of the solid ingredients, Common Salt, 81 parts;
Epsom Salts, 7 parts; Chloride of Magnesium, 10 parts; Chloride of
Potassium, 2 parts; and of Water about 2900 parts, although this must be
accurately determined by the specific gravity. The mixture had better
be allowed to stand several days before filling the tank; for thus the
impurities of the chemicals will settle, and the clear liquor can be
decanted off. The specific gravity should then be tested with the
hydrometer, and may safely range from 1026 to 1028,--fresh water being
1000. If a quart or two of real sea-water can be obtained, it is a very
useful addition to the mixture. It may now be introduced into the tank
through a filter. But no living creatures must be introduced until the
artificial water has been softened and prepared by the growth of the
marine plants in it for several weeks. Thus, too, it will be oxygenated,
and ready for the oxygen-using tenants.
It is a singular fact, that water which has been thus prepared, with
only four ingredients, will, after being a month or more in the
aquarium, acquire the other constituents which are normally present in
minute quantities in the natural sea-water. It must derive them from the
action of the plants or animals, or both. Bromine may come from sponges,
or sea-wrack, perhaps. Thus artificial water eventually rights itself.
The tank, having been prepared and seasoned with the same precaution
used for the river aquarium, and having a clear bottom and a supply of
good water, is now ready for planting. Many beautifully colored and
delicately fringed Algae and Sea-Wracks will be found on the rocks at
low tide, and will sadly tempt the enthusiast to consign their delicate
hues to the aquarium. All such temptations must be resisted. Green is
the only color well adapted for healthy and oxygenating growth in the
new tank. A small selection of the purple or red varieties may perhaps
be introduced and successfully cultivated at a later day, but they are
very delicate; while the olives and browns are pretty sure to die and
corrupt the water. It must be remembered, too, that the Algae are
cryptogamous, and bear no visible flowers to delight the eye or fancy.
Of all marine plants, the _Ulva latissima_, or Sea-Lettuce, is first and
best. It has broad, light-green fronds, and is hardy and a rapid grower,
and hence a good giver of oxygen. Next to this in looks and usefulness
comes the _Enteromorpha compressa_, a delicate, grass-like Alga. After
a while the _Chondrus crispus_, or common Carrageen Moss, may be chosen
and added. These ought to be enough for some months, as it is not safe
to add too many at once. Then the green weeds _Codium tomentosum_ and
_Cladophora_ may be tried; and, still later, the beautiful _Bryopsis
plumosa_. But it is much better to be content with a few Ulvae, and
others of that class, to begin with; for a half dozen of these will
support quite a variety of animal life.
After a few hardy plants are well set, and thriving for a week or two,
and the water is clear and bubbly with oxygen, it will be time to look
about for the live stock of the marine aquarium. Fishes, though most
attractive, must be put in last; for as they are of the highest
vitality, so they require the most oxygen and food, and hence should not
be trusted until everything in the tank is well a-going.
The first tenants should be the hardy varieties of the Sea-Anemones,
or _Actiniae_,--which are Polyps, of the class Radiata. The _Actinia
mesembryanthemum_ is the common smooth anemone, abounding on the coast,
and often to be found attached to stones on the beach. "When closed,"
says Mr. Hibbert, "it has much resemblance to a ripe strawberry,
being of a deep chocolate color, dotted with small yellow spots. When
expanded, a circle of bright blue beads or tubercles is seen within the
central opening; and a number of coral-like fingers or tentacles unfold
from the centre, and spread out on all sides." It remains expanded for
many days together, if the water be kept pure; and, having little desire
for locomotion, stays, generally, about where it is placed. It is
a carnivorous creature, and seeks its food with its ever-searching
tentacles, thus drawing in fishes and mollusks, but, most frequently,
the minute Infusoria. Like other polyps, it may be cut in two, and each
part becomes a new creature. It is a very pretty and hardy object in the
aquarium. There are many varieties, some of which are very delicate, as
the _Actinia anguicoma_, or Snaky-locked Anemone, and the pink and brown
_Actinia bellis_, which so resembles a daisy. Others, as the _Actinia
parasitica_, are obtainable only by deep-sea dredging; "and, as its name
implies, it usually inhabits the shell of some defunct mollusk. And more
curious still, in the same shell we usually find a pretty crab, who
acts as porter to the anemone. He drags the shell about with him like
a palanquin, on which sits enthroned a very bloated, but gayly-dressed
potentate, destitute of power to move it for himself."[B]
[Footnote B: Hibbert's _Book of the Aquarium_.]
The _Actinia gemmacea_, or Gemmed Anemone, the _Actinia crassicornis_,
and the Plumose Anemone are all beautiful, but tender varieties.
The Anemones require but little care; they do not generally need
feeding, though the Daisy and Plumose Anemone greedily take minced
mutton, or oyster. But, as a rule, there are enough Infusoria for their
subsistence; and it is safer not to feed them, as any fragments not
consumed will decay, and contaminate the water.
Next in order of usefulness, hardiness, and adaptability to the new
aquarium, come the Mollusks. And of these, Snails and Periwinkles claim
our respectful attention, as the most faithful, patient, and necessary
scavengers of the confervoid growths, which soon obscure the marine
aquarium.
"It is interesting," says Mr. Gosse, "to watch the business-like way in
which the Periwinkle feeds. At very regular intervals, the proboscis, a
tube with thick fleshy walls, is rapidly turned inside out to a certain
extent, until a surface is brought into contact with the glass having a
silky lustre; this is the tongue; it is moved with a short sweep,
and then the tubular proboscis infolds its walls again, the tongue
disappearing, and every filament of Conferva being carried up into the
interior, from the little area which had been swept. The next instant,
the foot meanwhile having made a small advance, the proboscis unfolds
again, the makes another sweep, and again the whole is withdrawn; and
this proceeds with great regularity. I can compare the action to nothing
so well as to the manner in which the tongue of an ox licks up the grass
of the field, or to the action of the mower cutting swath after swath."
Of Crustacea, the Prawns and the smaller kinds of Crabs may be
admitted to the aquarium, though but sparingly. They are rude, noisy,
quarrelsome, and somewhat destructive,--but, for the same reason,
amusing tenants of the tank.
All are familiar with the mode in which the Soldier or Hermit Crab takes
possession of and lives in the shells of Whelks and Snails. Poorly
protected behind by Nature, the homeless crab wanders about seeking a
lodging. Presently he meets with an empty shell, and, after probing it
carefully with his claw to be sure it is not tenanted, he pops into it
back foremost in a twinkling, and settles himself in his new house.
Often, too, he may be seen balancing the conveniences of the one he is
in and of another vacant lodging he has found in his travels; and he
even ventures out of his own, and into the other, and back again, before
being satisfied as to their respective merits. In all these manoeuvres,
as well as in his daily battles with his brethren, he is one of the
drollest of creatures.
As we advance in our practice with the aquarium we may venture to
introduce more delicate lodgers. Such are the beautiful family of the
_Annelidae_: the _Serpula_, in his dirty house; and the _Terebella_,
most ancient of masons, who lays the walls of his home in water-proof
cement.
The great class of Zoöphytes can be introduced, but many varieties of
them will be found already within the aquarium, in the company of their
more bulky neighbors. These peculiar creatures, or things, form the
boundary where the last gleam of animal life is so feeble and flickering
as to render it doubtful whether they belong to the animal or vegetable
kingdom. Agassiz calls them _Protozoa_,--Primary Existences. Some divide
them into two great classes, namely: the _Anthozoa_, or Flower-Life; and
the _Polyzoa_, or Many-Life, in which the individuals are associated in
numbers. They are mostly inhabitants of the water; all are destitute of
joints, nerves, lungs, and proper blood-vessels; but they all possess
an _irritable_ system, in obedience to which they expand or contract at
will. Among the _Anthozoa_ are the Anemones; among the _Polyzoa_,
are the Madrepores, or Coral-Builders, and many others. Many are
microscopic, and belong to the class of animalcules called _Infusoria_.
A very remarkable quality which the Infusoria possess--one very useful
for the aquarium, and one which would seem to settle their place in the
_vegetable_ kingdom--is that they _exhale oxygen_ like plants. This has
been proved by Liebig, who collected several jars of oxygen from tanks
containing Infusoria only.
A piece of honeycomb coral (_Eschara foliacea_) is easily found, and,
when well selected and placed in the aquarium, may continue to grow
there by the labors of its living infusorial tenants: they are not
unworthy rivals of the Madrepores, or deep-sea coral-builders of warmer
latitudes. The walls of its cells are not more than one-thirtieth of an
inch in thickness, and each cell has its occupant. So closely are they
packed, that in an area of one-eighth of an inch square the orifices of
forty-five cells can be counted. As these are all double, this would
give five thousand seven hundred and sixty cells to the square inch. Now
a moderate-sized specimen will afford, with all its convolutions,
at least one hundred square inches of wall, which would contain a
population of five hundred and seventy-six thousand inhabitants,--a very
large city. So says Mr. Gosse. We cannot forbear, with him, from quoting
Montgomery's lines on the labors of the coral-worms, which modern
science has enabled us to study in our parlors.
"Millions on millions thus, from age to age,
With simplest skill, and toil unweariable,
No moment and no movement unimproved,
Laid line on line, on terrace terrace spread,
To swell the heightening, brightening, gradual mound,
By marvellous structure climbing towards the day.
Each wrought alone, yet all together wrought,
Unconscious, not unworthy instruments,
By which a hand invisible was rearing
A new creation in the secret deep.
.....I saw the living pile ascend,
The mausoleum of its architects,
Still dying upwards as their labors closed;
Slime the material, but the slime was turned
To adamant by their petrific touch:
Frail were their frames, ephemeral their lives,
Their masonry imperishable."
The deep-sea soundings taken recently for the Atlantic telegraph have
demonstrated the existence of organic life even at the bottom of the
ocean. Numerous living Infusoria have been brought to the light of day,
from their hidden recesses, by the lead. "Deeper than ever plummet
sounded" before these latter days, there exist myriads of minute
creatures, and of Algae to furnish their food. It is an unanswered
problem, How they can resist the enormous pressure to which they must
be there subjected, amounting, not infrequently, to several tons to the
square inch. And still another point of interest for us springs
from this. It is an inquiry of practical importance to the aquarian
naturalist, How far the diminished pressure which they meet with in the
tank, on being transferred from their lower homes to the aquarium, may
influence their viability. May not some of the numerous deaths in the
marine tank be reasonably attributed to this lack of pressure?
What a difference, too, has Nature established, in the natural power to
resist pressure, between those creatures which float near the surface
and those which haunt the deeper sea! The Jelly-fish can live only near
the top of the water, and, floating softly through a gentle medium, is
yet crushed by a touch; while the Coral-builder bears the superincumbent
weight of worlds on his vaulted cell with perfect impunity.
Another important question is, How far alteration in the amount of light
may affect the more delicate creatures. What fishes do without light has
been solved by the darkness of the Mammoth Cave, the tenants of whose
black pools are eyeless, evidently because there is nothing to see. The
more deeply located Infusoria and Mollusks must dwell in an endless
twilight; for Humboldt has found, by experiment, that at a depth one
hundred and ninety-two feet from the surface the amount of sunlight
which can penetrate is equal only to one-half of the light of an
ordinary candle one foot distant.
Thus ever in gloom, yet in a state of constant safety from storms and
the agitations of the upper air, the thousand forms of low organic life
and cryptogamic vegetation live and thrive in peace and quietness.
"The floor is of sand like the mountain drift,
And the pearl-shells spangle the flinty snow;
From the coral rocks the sea-plants lift
Their boughs, where the tides and billows flow.
* * * * *
"And life in rare and beautiful forms
Is sporting amid those bowers of stone,
And is safe, when the wrathful spirit of storms
Has made the top of the waves his own."[C]
[Footnote C: Percival.]
Upon the bottom, at various depths, lies that brilliant Radiate--type of
his class--the Star-fish. These are quiet and harmless creatures, and
favorites in the aquarium, from the pretty contrast they make with
marine plants and other objects.
The perfect transparency, elegant form, and graceful navigation of the
_Medusae_, or Jelly-fishes, render them much admired in their native
haunts, and prized for the aquarium. But they are very delicate. How
beautiful and remarkable are these headless _Discophori_, as they
float, and propel themselves with involutions of their disks and gently
trailing tentacles, and the central peduncle hanging far below, like the
clapper of a transparent bell! And yet these wonders are but so much
sea-water, inclosed in so slight a tissue that it withers in the sun,
and leaves only a minute spot of dried-up gelatinous substance behind.
Finally come the Fishes, many of which are of similar genera to those
recommended for the fresh-water tank. The Black Goby is familiar,
tamable, but voracious; the Gray Mullet is very hardy, but also rather
savage; the Wrasses are some of the most showy fish,--called in some
parts of the country Cunners,--and of these, the Ancient Wrasse,
(_Labrus maculatus_,) covered with a network of vermilion meshes on a
brown and white ground, is the most elegant.
Some points of general management are so important, and some dangers so
imminent, that we cannot pass them by unnoticed. The aquarian enthusiast
is very apt to be in too great haste to see everything going on, and
commits the common error of trying too many things at once. The aquarium
must be built up slowly and tentatively, object by object: plants first,
and of the simplest kinds; and not until they are well settled, and the
water beaded with oxygen bubbles, should we think of introducing living
creatures,--and even then only the hardier kinds of actinias, mollusks,
and crabs. All delicate animals must be intrusted one by one to their
new home, and carefully watched for deaths and decay, which, whether
arising from dead plants or animals, ruin everything very quickly,
unless they be promptly removed. For sulphuretted hydrogen, even in very
minute quantities, is sure death to all these little creatures.
The emanations from paint and putty are often fatal in new tanks.
Several weeks' exposure to water, air, and sunlight is necessary to
season the new-made aquarium. Of equal consequence is it that the water
be absolutely pure; and if brought from the sea, care must be exercised
about the vessel containing it. Salt acts upon the glazing of earthen
ware of some kinds. Stone or glass jars are safest. New oak casks are
fatal from the tannin which soaks out; fir casks are safe and good. So
delicate and sensitive are the minute creatures which people the sea,
that they have been found dead on opening a cask in which a new oak
bung was the only source of poison. And no wonder; for a very slight
proportion of tannic acid in the water corrugates and stiffens the thin,
smooth skin of the anemone, like the tanning of leather.
A certain natural density of the sea-water must also be preserved,
ranging between no wider limits than 1026 and 1028. And in the open tank
evaporation is constantly deranging this, and must be met by a supply
from without. As the pure water alone evaporates, and the salts and
earthy or mineral constituents are left behind, two things result: the
water remaining becomes constantly more dense; and this can be remedied
only by pure fresh water poured in to restore the equilibrium. Hence the
marine aquarium must be replenished with _fresh water_, until the proper
specific gravity, as indicated by the hydrometer, is restored.
The aquarium may be found some morning with a deep and permanent green
stain discoloring the water. This unsightly appearance is owing to the
simultaneous development of the spores of multitudes of minute Algae and
Confervae, and can be obviated by passing the water through a charcoal
filter. When any of the fishes give signs of sickness or suffocation, by
coming to the surface and gulping air, they may be revived by having the
water aerated by pouring it out repeatedly from a little elevation, or
by a syringe. The fishes are sometimes distressed, also, when the room
gets too warm for them. A temperature of 60° is about what they require.
And they will stand cold, many of them, even to being frozen with the
water into ice, and afterwards revive.
The degree of light should be carefully regulated by a stained glass
side, or a shade. Yet it must be borne in mind that sunlight is
indispensable to the free evolution of oxygen by the plants. And when
the sun is shining on the water, all its occupants appear more lively,
and the fishes seem intoxicated--as they doubtless are--with oxygen.
A novice is apt to overstock his aquarium. Not more than two
moderate-sized fishes to a gallon of water is a safe rule. Care, too,
must be taken to group together those kinds of creatures which are not
natural enemies, or natural food for each other, or a sad scene of
devastation and murder will ensue.
Cleansing cannot be always intrusted to snails. But the sides may be
scrubbed with a soft swab, made of cotton or wick-yarn. Deaths will
occasionally take place; and even suicide is said to be resorted to by
the wicked family of the Echinoderms.
To procure specimens for the aquarium requires some knack and knowledge.
The sea-shore must be haunted, and even the deep sea explored. At the
extreme low-water of new or full moon tides, the rocks and tide-pools
are to be zealously hunted over by the aquarian naturalist. Several
wide-mouthed vials and stone jars are necessary; and we would repeat,
that no plant should be taken, unless its attachment is preserved. It
is often a long and difficult job to get some of the Algae; with their
tender connections unsevered from the hard rock, which must be chipped
away with the chisel, and often with the blows of the hammer deadened by
being struck under water. It is by lifting up the overhanging masses of
slimy fuel, tangles, and sea-grass, that we find the delicate varieties,
as the _Chondrus_ with its metallic lustre, and the red _Algae_, or the
stony _Corallina_, which delights in the obscurity of shaded pools.
The sea-weeds will be found studded with mollusks,--as Snails and
Periwinkles of many queer varieties. Anemones, of the more common kinds,
are found clinging to smooth stones. Crabs on the sand. Prawns, Shrimps,
Medusae, and fishes of many species, in the little pools which the tide
leaves behind, and which it will require a sharp eye and a quick hand
to explore with success. But the rarer forms of Actinias, Star-fishes,
Sepioles, Madrepores, Annelidae, and Zoophytes, of a thousand shapes,
live on the bottom, in deep water, and must be captured there.
For this purpose we must dredge from a boat, under sail. The
naturalist's dredge is an improved oyster-dredge, with each of the two
long sides of the mouth made into a scraping lip of iron. The body is
made of spun-yarn, or fishing-line, netted into a small mesh. Two long
triangles are attached by a hinge to the two short sides of the frame,
and meeting in front, at some distance from the mouth, are connected by
a swivel-joint. To this the dragging rope is bent, which must be three
times as long, in dredging, as the depth of the water. This is fastened
to the stern of a boat under sail, and thus the bottom is raked of
all sorts of objects; among which, on emptying the net, many living
creatures for the aquarium are found. These may be placed temporarily in
jars; though plants, mollusks, Crustacea and Actiniae may be kept and
transmitted long distances packed in layers of moist sea-weed.
For all this detail, labor, and patient care, we may reasonably find
two great objects: first, the cultivation and advancement of natural
science; second, the purest delight and healthiest amusement.
In the aquarium we have a most convenient field for the study of
Natural History: to learn the varieties, nature, names, habits, and
peculiarities of those endless forms of animated existence which dwell
in the hidden depths of the sea, and at the same time to improve our
minds by cultivating our powers of observation.
The pleasure derived from the aquarium comes from the excitement of
finding and collecting specimens, as well as from watching the tank
itself. There can be no more pleasant accompaniment to the sea-side walk
of the casual visitor or summer resident of a watering-place, than to
search for marine plants and animals among the fissures, rocks, and
tide-pools of the sea-washed beach or cape.
Nature is always as varied as beautiful. Thousands of strange forms
sport under the shadow of the brown, waving sea-weeds, or among the
delicate scarlet fronds of the dulse, which is found growing in the
little ponds that the inequalities of the beach have retained. It is
down among the great boulders which the Atlantic piles upon our coast,
that we may find endless varieties of life to fill the aquarium, though
not those more gorgeous hues which distinguish the tenants of the coral
reefs on tropical shores. Yet even here Nature is absolutely infinite;
and we shall find ourselves, day after day, imitating that botanist who,
walking through the same path for a month, found always a new plant
which had escaped his notice before. So, too, in exploring the open sea,
besides the pleasure of sailing along a variegated coast, with sun and
blue water, we have the constant excitement of unexpected discovery:
for, as often as we pull up the dredge, some new wonder is revealed.
Words fail to describe the wonders of the sea. And all that we drag
from the bottom, all that we admire in the aquarium, are but a few
disconnected specimens of that infinite whole which makes up their home.
So, too, in watching the aquarium itself, we shall see endless
repetitions of those "sea-changes" which Shakspeare sang. Ancient
mythology typified the changing wonders of aquatic Nature, as well
as the fickleness of the treacherous sea, in those shifting deities,
Glaucus and Proteus, who tenanted the shore.
The one the fancy of Ovid metamorphosed from a restless man to a fickle
sea-god; the other assumed so many deceptive shapes to those who visited
his cave, that his memory has been preserved in the word Protean. Such
fancies well apply to a part of Nature which shifts like the sands, and
ranges from the hideous Cuttle-fish and ravenous Shark to the delicate
Medusa, whose graceful form and trailing tentacles float among the
waving fronds of colored Algae, like
"Sabrina fair,
Under the glassy, cool, translucent wave,
In twisted braids of lilies knitting
The loose train of her amber-dropping hair."
* * * * *