glaucus-or the wonders of the shore(格劳高斯)-第29部分
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that the sucking base is downwards； and leave them to themselves
thenceforth。
These two species （Mesembryanthemum and Crassicornis） are quite
beautiful enough to give a beginner amusement： but there are two
others which are not uncommon； and of such exceeding loveliness； that
it is worth while to take a little trouble to get them。 The one is
Dianthus； which I have already mentioned； the other Bellis； the sea…
daisy； of which there is an excellent description and plates in Mr。 Gosse's
〃Rambles in Devon；〃 pp。 24 to 32。
It is common at Ilfracombe； and at Torquay； and indeed everywhere
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where there are cracks and small holes in limestone or slate rock。 In
these holes it fixes its base； and expands its delicate brown… grey star…like
flowers on the surface： but it must be chipped out with hammer and
chisel； at the expense of much dirt and patience； for the moment it is
touched it contracts deep into the rock； and all that is left of the daisy
flower； some two or three inches across； is a blue knot of half the size of
a marble。 But it will expand again； after a day or two of captivity； and
will repay all the trouble which it has cost。 Troglodytes may be found；
as I have said already； in hundreds at Hastings； in similar situations to
that of Bellis； its only token； when the tide is down； being a round
dimple in the muddy sand which firs the lower cracks of rocks。
But you will want more than these anemones； both for your own
amusement； and for the health of your tank。 Microscopic animals will
breed； and will also die； and you need for them some such scavenger as
our poor friend Squinado； to whom you were introduced a few pages
back。 Turn； then； a few stones which lie piled on each other at extreme
low…water mark； and five minutes' search will give you the very animal
you want； … a little crab； of a dingy russet above； and on the under side
like smooth porcelain。 His back is quite flat； and so are his large
angular fringed claws； which； when he folds them up； lie in the same
plane with his shell； and fit neatly into its edges。 Compact little rogue
that he is； made especially for sidling in and out of cracks and crannies；
he carries with him such an apparatus of combs and brushes as Isidor
or Floris never dreamed of； with which he sweeps out of the sea… water at
every moment shoals of minute animalcules； and sucks them into his
tiny mouth。 Mr。 Gosse will tell you more of this marvel； in his
〃Aquarium；〃 p。 48。
Next； your sea…weeds； if they thrive as they ought to do； will sow
their minute spores in millions around them； and these； as they vegetate；
will form a green film on the inside of the glass； spoiling your prospect：
you may rub it off for yourself； if you will； with a rag fastened to a stick；
but if you wish at once to save yourself trouble； and to see how all
emergencies in nature are provided for； you will set three or four live
shells to do it for you； and to keep your sub…aqueous lawn close mown。
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That last word is no figure of speech。 Look among the beds of sea…
weed for a few of the bright yellow or green sea…snails （Nerita）； or
Conical Tops （Trochus）； especially that beautiful pink one spotted with
brown （Ziziphinus）； which you are sure to find about shaded rock…ledges
at dead low tide； and put them into your aquarium。 For the present；
they will only nibble the green ulvae； but when the film of young weed
begins to form； you will see it mown off every morning as fast as it
grows； in little semicircular sweeps； just as if a fairy's scythe had been at
work during the night。
And a scythe has been at work； none other than the tongue of the
little shell…fish； a description of its extraordinary mechanism （too long to
quote here； but which is well worth reading） may be found in Gosse's
〃Aquarium。〃 （32）
A prawn or two； and a few minute star…fish； will make your aquarium
complete； though you may add to it endlessly； as one glance at the salt…
water tanks of the Zoological Gardens； and the strange and beautiful
forms which they contain； will prove to you sufficiently。
You have two more enemies to guard against； dust； and heat。 If the
surface of the water becomes clogged with dust； the communication
between it and the life…giving oxygen of the air is cut off； and then your
animals are liable to die； for the very same reason that fish die in a pond
which is long frozen over； unless a hole be broken in the ice to admit the
air。 You must guard against this by occasional stirring of the surface； or；
as I have already said； by syringing and by keeping on a cover。 A piece
of muslin tied over will do； but a better defence is a plate of glass； raised
on wire some half…inch above the edge； so as to admit the air。 I am not
sure that a sheet of brown paper laid over the vase is not the best of all；
because that； by its shade； also guards against the next evil； which is heat。
Against that you must guard by putting a curtain of muslin or oiled paper
between the vase and the sun； if it be very fierce； or simply （for simple
expedients are best） by laying a handkerchief over it till the heat is past。
But if you leave your vase in a sunny window long enough to let the
water get tepid； all is over with your pets。 Half an hour's boiling may
frustrate the care of weeks。 And yet； on the other hand； light you must
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have； and you can hardly have too much。 Some animals certainly
prefer shade； and hide in the darkest crannies； and for them； if your
aquarium is large enough； you must provide shade； by arranging the bits
of stone into piles and caverns。 But without light； your sea…weeds will
neither thrive nor keep the water sweet。 With plenty of light you will
see； to quote Mr。 Gosse once more； （33） 〃thousands of tiny globules
forming on every plant； and even all over the stones； where the infant
vegetation is beginning to grow； and these globules presently rise in
rapid succession to the surface all over the vessel； and this process goes
on uninterruptedly as long as the rays of the sun are uninterrupted。
〃Now these globules consist of PURE OXYGEN； given out by the
plants under the stimulus of light； and to this oxygen the animals in the
tank owe their life。 The difference between the profusion of oxygen…
bubbles produced on a sunny day； and the paucity of those seen on a
dark cloudy day； or in a northern aspect； is very marked。〃 Choose；
therefore； a south or east window； but draw down the blind； or throw a
handkerchief over all if the heat become fierce。 The water should
always feel cold to your hand； let the temperature outside be what it
may。
Next； you must make up for evaporation by FRESH water （a very
little will suffice）； as often as in summer you find the water in your vase
sink below its original level； and prevent the water from getting too salt。
For the salts； remember； do not evaporate with the water； and if you left
the vase in the sun for a few weeks； it would become a mere brine…pan。
But how will you move your treasures up to town？
The simplest plan which I have found successful is an earthen jar。
You may buy them with a cover which screws on with two iron clasps。
If you do not find such； a piece of oilskin tied over the mouth is enough。
But do not fill the jar full of water； leave about a quarter of the contents
in empty air； which the water may absorb； and so keep itself fresh。 And
any pieces of stone； or oysters； which you send up； hang by a string from
the mouth； that they may not hurt tender animals by rolling about the
bottom。 With these simple precautions；
