_THE PRESERVATION OF MARINE OBJECTS_
The sea-side naturalist, in the course of his ramblings and searchings
on the coast, will certainly come across many objects, dead or alive,
that he will desire to set aside for future study or identification in
his leisure moments at home. Some of these will be required for
temporary purposes only, while, most probably, a large proportion will
be retained permanently for the establishment of a private museum, that
shall serve not only as a pleasant reminder of the many enjoyable hours
spent on the shore, but also as a means of reference for the study of
the classification of natural objects and of their distribution and
habitats.
We will first deal with those specimens that are required for temporary
purposes only--those of which the collector desires to study the general
characters, as well as, perhaps, something of the internal structure;
but before doing so we cannot refrain from impressing on the reader the
advisability of learning as much as possible of the external features
and mode of growth of the different living creatures while still alive,
for it must be remembered that it is impossible to preserve many of them
without more or less destruction of their natural colouring and
distortion of their characteristic forms.
In those cases where it is possible to keep the creatures alive for a
short time only, it is a good plan to make notes of their movements and
all observed changes in form, and their methods of feeding, and also to
illustrate these notes by sketches drawn from life. This may seem quite
an unnecessary procedure to many beginners in the study of natural
objects, and may even, as far as the sketches are concerned, present
difficulties that at first appear to be insurmountable; but the power to
sketch from nature will surely be acquired to a greater or less degree
by constant practice, and illustrated notes prepared for the purpose we
suggest will undoubtedly be of great value to the student. Further,
though it may often be necessary to set specimens aside in a
preservative fluid until one has the leisure to examine their structure,
it should always be remembered that they never improve by keeping, also
that they are rarely in such good condition for dissection after
saturation with the preservative as when perfectly fresh.
One of the most convenient preservatives for general use is undoubtedly
methylated spirit. This is alcohol that has been adulterated in order to
render it undrinkable, so that it may be sold free from duty for use in
the various arts and manufactures without any danger of its being
employed for the concoction of beverages. It may be used just as
purchased--that is, in its strongest condition--for many purposes, but
in this state it has a powerful affinity for water, and will rapidly
abstract water from animal and vegetable objects, causing the softer
ones to become hard, shrunken, and shrivelled, often to such an extent
that they are almost beyond recognition.
By diluting the spirit, however, we satisfy to a great extent its
affinity for water, and thus prevent, or, at least, reduce the action
just mentioned. A mixture of equal quantities of spirit and water is
quite strong enough. Unfortunately the common methylated spirit of the
shops produces a fine white precipitate, that gives the whole mass a
milky appearance, when it is diluted. This is due to the presence of
mineral naphtha, which is added in a certain fixed proportion in
accordance with the Government regulations. But it _is_ possible, by
special application, to obtain the ‘non-mineralised’ or ‘ordinary’
methylated spirit of former years, though not in small quantities, and
this liquid dissolves in water without the formation of a precipitate.
It should be noted, however, that the use of the spirit as a
preservative is in no way interfered with by the presence of the mineral
naphtha, the only disadvantage of this impurity lying in the fact that
the milkiness consequent on dilution prevents the objects in a specimen
jar from being observed without removal.
We have just referred to the hardening action of strong spirit as a
disadvantage, and so it is when it is required to preserve soft
structures with as little as possible of change in general form and
appearance; but there are times when it becomes necessary to harden
these soft structures in order that sections may be made for the purpose
of examining internal structure with or without the aid of the
microscope, and for such purposes strong spirit is one of the best
hardening agents that can be employed.
Formaldehyde is another very good preservative. It is a colourless
liquid, and should be considerably diluted for use, a two per cent.
solution being quite strong enough for all ordinary purposes. It
possesses some distinct advantages as compared with spirit. In the first
place, it does not destroy the natural colours of objects to the extent
that spirit does; and, although a hardening agent as well as a
preservative, it does not harden soft structures by the extraction of
the water they contain, and therefore does not cause them to become
shrivelled or otherwise distorted. It will also occur to the reader
that, since a small bulk of formaline represents a large volume of the
diluted preservative, it is very conveniently stored, and a very small
bottle of it taken for outdoor work may, on dilution with water, be made
to yield all that is required for the preservation of the takings of a
successful day, or even of a longer period. Formaldehyde is usually sold
in solution of about forty per cent. strength, and for the preparation
of a two per cent. solution it will be found convenient to provide a
glass measure graduated either into cubic centimetres or fluid ounces
and drams. One hundred volumes of the original solution contain forty of
pure formaldehyde, and if water be added to make this up to two thousand
volumes, a two per cent. solution is obtained. Thus, one hundred cubic
centimetres of the original solution is sufficient to prepare two litres
(three and a half pints) of suitable preservative.
A very good preservative liquid may be made by dissolving two ounces of
common salt, one ounce of alum, and two or three grains of corrosive
sublimate (a deadly poison) in one quart of water, and then, after
allowing all sedimentary matter to settle to the bottom, decanting off
the clear solution. This mixture is known as <i>Goadby’s fluid</i>, and is
well adapted for the preservation of both animal and vegetable
structures. It does not cause any undue contraction of soft tissues,
and, as a rule, does not destroy the natural colours of the objects kept
in it.
Glycerine is valuable as a preservative for both animal and vegetable
objects, and especially for the soft-bodied marine animals that form
such a large percentage of the fauna of our shores. It maintains the
tissues in a soft condition, and preserves the natural tints as well as
any liquid.
An inexpensive preservative may also be made by dissolving chloride of
zinc--about one ounce to the pint of water. This is considered by some
to be one of the best fluids for keeping animal structures in good
condition.
Now, although the different fluids here mentioned are described in
connection with the _temporary_ preservation of natural objects, it must
be remembered that they are equally adapted for the permanent
preservation of the animals and plants that are to figure in the museum
of the sea-side naturalist; and, although some marine objects may be
preserved in a dry state in a manner to be hereafter described, yet
there are many species of animals, and also some plants, that can be
satisfactorily preserved only by immersion in a suitable fluid.
This method may be applied to all soft-bodied animals, such as anemones,
jelly-fishes, marine worms, shell-less molluscs (sea slugs, cephalopods,
&c.), the soft parts of shelled molluscs, fishes, &c.; and most sponges
retain their natural appearance much better in a preservative fluid than
in a dry condition. Many sea-weeds also, which are practically destroyed
by the most careful drying process, are most perfectly preserved in
fluid.
But the puzzled amateur will probably be inclined to ask: ‘Which is the
best preservative liquid for this or that specimen?’ No satisfactory
general rule can be given in answer to such a question, and a great deal
will have to be determined by his own experiments and observations.
Whenever he has two or three specimens of the same object, as many
different fluids should be employed, and the results compared and noted.
In this way a very great deal of useful information will be obtained and
by the best possible means. However, it may be mentioned that all the
fluids alluded to above may be safely used for almost every animal or
vegetable specimen with the following reservations: strong spirit should
not be employed for _any_ very soft animal, nor should it be used for
delicate green plants, since it will dissolve out the green colouring
matter (_chlorophyll_), leaving them white or almost colourless.
Further, the greatest care should be exercised in dealing with sea
anemones and jelly-fishes. If spirit is used for preserving these
creatures, it should be very dilute, at least at first, but may with
advantage be increased in strength afterwards, though this should be
done gradually.
Whatever be the preservative used, it is sure to be more or less charged
with sedimentary and coloured matter extracted from the object immersed
in it; hence, if the specimen concerned is to form part of a museum
collection, it will be necessary to transfer it to a fresh solution
after a time, and a second, and even further changes may be necessary
before the object ceases to discolour the fluid or render it turbid.
Considerable difficulty will sometimes be found in the attempts to
preserve a soft-bodied animal in its natural attitude. Thus, when a sea
anemone is removed from its native element, it generally withdraws its
tentacles, and, contracting the upper part of its cylindrical body,
entirely conceals these appendages, together with the mouth they
surround; and a mollusc similarly treated will generally pull itself
together within its shell, leaving little or no trace of the living body
inhabiting the lifeless case. Then, if these animals are transferred to
any fluid other than sea water, or placed anywhere under unnatural
conditions, they usually remain in their closed or unexpanded form.
Thus, almost every attempt to kill them for preservation deprives them
of just the characteristics they should retain as museum specimens.
Some such animals may be dealt with satisfactorily as follows: Transfer
them to a vessel of fresh sea water, and leave them perfectly
undisturbed until they assume the desired form or attitude. Then add a
_solution_ of corrosive sublimate very gradually--a drop or two at
intervals of some minutes. In this way the bodies of anemones may be
obtained ready for preservation with expanded tentacles, tube-secreting
worms with their heads and slender processes protruding from their limy
or sandy cases, molluscs with their ‘feet’ or their mantles and gills
protruding from their shells, and barnacles with their plume-like
appendages projecting beyond the opening of their conical shells.
The specimens thus prepared may be placed at first in very dilute
spirit, and then, after a time, finally stored in a stronger solution of
spirit in water; or they may be transferred to one of the other
preservative solutions previously mentioned.
All specimens permanently preserved in fluid for a museum should be
placed in jars, bottles, or tubes of suitable size, each vessel
containing, as a rule, only one. Where expense is no object, stoppered
jars made expressly for biological and anatomical specimens may be used
for all but the smallest objects; or, failing this, ordinary
wide-mouthed bottles of white glass, fitted with good corks or glass
stoppers.
For very small specimens nothing is more suitable than glass tubes, but
it must be remembered that wherever corks are used, even if they are of
the best quality procurable, it will be necessary to look over the
specimens occasionally to see if the preserving fluid has disappeared to
any extent either by leakage or evaporation; for such loss is always
liable to occur, although it may be very slow, and especially when
methylated spirit is the liquid employed.
[Illustration: FIG. 40.--JARS FOR PRESERVING ANATOMICAL AND BIOLOGICAL
SPECIMENS]
The writer has preserved many hundreds of small marine and other objects
in glass tubes of dilute spirit that have been hermetically sealed, thus
rendering the slightest loss absolutely impossible, while the perfect
exclusion of air prevents the development of fungoid growths that
sometimes make their appearance in imperfectly preserved specimens. The
making and closing of such tubes, though a more or less difficult
operation at first to those who have had no previous experience in
glass-working, become exceedingly simple after a little practice; and
believing it probable that many of our readers would like to try their
hand at this most perfect method of preserving and protecting small
objects, we will give a description of the manner in which it is done.
The apparatus and materials required for this work are:--Lengths of
‘soft’ glass tubing, varying from about one quarter to a little over
half an inch in internal diameter; a supply of diluted spirit--about
half spirit and half water; a Herapath blowpipe, preferably with
foot-bellows; and a small triangular file.
The glass tubing may be cut into convenient lengths by giving a single
sharp stroke with the file, and then pulling it apart with, at the same
time, a slight bending _from_ the cut made.
[Illustration: FIG. 41.--SHOWING THE DIFFERENT STAGES IN THE MAKING OF
A SMALL SPECIMEN TUBE]
Cut a piece of tubing about eight or nine inches long, heat it in the
blowpipe flame, turning it round and round all the time, until it is
quite soft, then remove it from the flame and immediately pull it out
_slowly_ until the diameter in the middle is reduced to about a
sixteenth of an inch (fig. 41, 2). Make a slight scratch with the file
at the narrowest part, and divide the tube at this point (fig. 41, 3).
Now heat one of these pieces of tubing as before just at the point where
the diameter of the drawn part begins to decrease; and, when very soft,
pull it out rather quickly while it is _still in the flame_. The part
pulled now becomes completely separated, and the tube is closed, but
pointed. Continue to heat the closed end, directing the flame to the
point rather than to the sides, until the melted glass forms a rather
thick and flattened end; and then, immediately on removing it from the
flame, blow gently into the open end until the melted glass is nicely
rounded like the bottom of a test-tube (fig. 41, 4). When the tube is
cold, the specimen that it is to contain, and which has already been
stored for a time in dilute spirit, is dropped into it. The tube is now
heated about an inch above the top of the specimen, drawn out as shown
in fig. 41, 5, and again allowed to cool. When cold, the fresh spirit is
poured into the open end of the tube, but the middle part is so narrow
that the spirit will not run down freely. If, however, suction be
applied to the open end, air from the bottom will bubble through the
spirit, and then, on the cessation of the suction, the spirit will pass
down to take the place of the air that was withdrawn. This may be
repeated if necessary to entirely cover the specimen with the fluid. Any
excess of spirit is then thrown from the upper part of the tube, and the
latter cut off. Nothing is now left but to close the tube hermetically.
This is done by heating the lower part of the narrow neck, and then
drawing it out _in the flame_, taking great care that the tube is
withdrawn from the flame the moment it is closed. The tube must also be
kept in an upright position until it has cooled. The appearance of the
finished tube is shown in fig. 41, 6.
[Illustration: FIG. 42.--SMALL SPECIMEN TUBE MOUNTED ON A CARD]
All preserved specimens should have a label attached on which is written
the name of the specimen, the class and order to which it belongs, the
locality in which it was found, together with any brief remarks that the
owner desires to remember concerning its habits &c.
The bottles or tubes that are too small to have a label attached to them
in the ordinary way may be mounted on a card, as represented in fig. 42,
and the desired particulars then written on the card.
When soft or delicate specimens are preserved in a bottle of fluid they
frequently require some kind of support to keep them in proper form and
to display them better for observation. Perhaps the best way to support
them is to fasten them to a very thin plate of mica of suitable size by
means of a needle and very fine thread. The mica is so transparent that
it is invisible in the fluid, and the few stitches are also hardly
perceptible, thus making it appear as if the specimen floats freely in
the fluid.
We will now pass on to consider those objects of the shore that are
usually preserved in a dry condition, commencing with
STARFISHES AND SEA URCHINS
Starfishes are commonly preserved by simply allowing them to dry in an
airy place, with or without direct exposure to the sun’s rays, and this
method is fairly satisfactory when the drying proceeds rapidly; but care
should be taken to maintain the natural roughness of the exterior as
well as to have the numerous suckers of the under surface as prominent
as possible. If the starfish is simply laid out on some surface to dry,
the side on which it rests is often more or less flattened by the weight
of the specimen itself, which therefore becomes adapted for the future
examination of one surface only; but a better result, as regards both
the rapidity of drying and the after appearance of the specimen, may be
obtained by suspending it on a piece of fine net or by threads. A still
better plan is to put the dead starfish into _strong_ spirit, which will
rapidly extract the greater part of the moisture that its body
contained. After allowing it to remain in this for a day or two to
harden it, put it out to dry as before mentioned. The spirit, being very
volatile, will soon evaporate, so that the specimen will shortly be
ready for storing away.
It is most important to observe that dried specimens--not starfishes
only, but all animal and vegetable objects--should never be placed in
the cabinet or other store-case until _perfectly_ dry, for a very small
amount of moisture left in them will often encourage the development of
moulds, not only on themselves, but on other specimens stored with them.
Very small and delicate starfishes, when preserved in a dry condition,
may be protected from injury by fastening them on a card by means of a
little gum, or by keeping them permanently stored on cotton wool in
glass-topped boxes.
Sea urchins, or sea eggs, as they are commonly called, may be preserved
exactly in the same way as starfishes, though it is more essential in
the case of these to soak them in strong spirit previous to drying,
otherwise the soft animal matter within the shell will decompose before
the drying is complete. Here, however, it is possible to remove the
whole interior with the aid of a piece of bent wire, and to thoroughly
clean the inner surface of the shell before drying it.
Some of the shells should be preserved with the spines all intact, and
others with these removed in order to show the arrangement of the
plates which compose the shell, as well as the perforations, and the
rounded processes to which the spines are articulated.
The majority of sea urchins are provided with a most complicated and
beautiful arrangement of teeth which are well worthy of study. These
should be removed from a moderately large specimen, the soft surrounding
structures carefully dissected away, and then cleaned by means of an old
tooth-brush without disarranging them.
It will be found that dried sea urchins will require care when preserved
with spines attached, for these appendages are usually very brittle and
are easily dislocated at their bases where they are united to the shell
by ball-and-socket joints.
It may be mentioned here that corrosive sublimate is very valuable for
preventing the development of mould on the surfaces of starfishes, sea
urchins, and museum specimens generally. It is best supplied in the form
of an alcoholic solution made by dissolving a few grains in about half a
pint of methylated spirit; the advantage of this over an aqueous
solution being the rapidity with which it dries. In most cases it is
simply necessary to apply the solution to the object by means of a soft
brush, but, as regards starfishes and urchins it is far better to
dissolve a few grains of the corrosive sublimate in the spirit in which
the objects are placed previous to drying.
CRUSTACEANS
The preservation of crustaceans by the dry method often requires some
care and demands a certain amount of time; but the process is never
really difficult, and the satisfaction of having produced a good
specimen for a permanent collection well repays one for the trouble
taken and time spent.
Some of our crustaceans are only partially protected by a firm outer
covering, and almost every attempt to preserve these as dry objects
results in such a shrivelling of the soft tissues that the natural
appearance is quite destroyed. This is the case with some of the
barnacles, and the abdominal portion of the bodies of hermit crabs,
which are, therefore, far better preserved in fluid. Dilute spirit is
quite satisfactory for most of these as far as the preservation of the
soft structures is concerned, but it has the disadvantage that it turns
the shells of some crustaceans red, making them appear as if they had
been boiled.
Other crustaceans are so small, or are hardened externally to such a
slight extent, that they also are not adapted for the dry method of
preservation. Speaking generally, such crustaceans as shrimps and
sand-hoppers are best preserved in fluid, while the different species of
crabs and lobsters are more conveniently preserved dry unless it is
desired to study any of their soft structures.
It is quite impossible to remove the soft parts from small crabs and
lobsters previous to drying them, hence the drying should be conducted
as rapidly as possible, so that no decomposition may set in. Where the
process goes on very slowly, as is the case when the air is damp, or
when the specimens are not set out in an airy spot, a decay of the soft
structures soon proceeds, and the products of this decay will generally
saturate the whole specimen, giving rise to most objectionable odours,
and destroying the natural colour of the shell.
If it has been found that the species in question are not reddened by
the action of methylated spirit, they should be allowed to remain in
this fluid, with a few grains of dissolved corrosive sublimate, for at
least a few hours, and then they will dry rapidly without any signs of
putrefaction; and even those species that _are_ reddened by spirit may
be treated to a shorter immersion in this fluid with advantage.
The specimens should always be set out in some natural attitude to dry,
unless it is desired to spread out the various appendages in some manner
that is more convenient for the study of their structure. A sheet of
blotting-paper may be placed on cork or soft wood, the specimens placed
on this, and the appendages kept in the desired positions when necessary
by means of pins placed beside, but not thrust through them. When more
than one specimen of the same species has been collected, one should be
set in such a manner as to exhibit the under side; and, further, in
instances where the male and female of the same crustacean differ in
structure, as is commonly the case, two of each should be preserved, one
displaying the upper, and the other the under surface.
When perfectly dry, all small crustaceans should be mounted on cards
with the aid of a little gum, and the name and other particulars to be
remembered then written on the card.
The question may well be asked: ‘Which is the best gum to use?’ In
answer to this we may say that gum tragacanth is certainly as good as
any. It holds well, and leaves no visible stain on a white card. A small
quantity of the solid gum should be put into a bottle with water in
which a grain or so of corrosive sublimate has been dissolved. It
absorbs much water, becoming a very soft, jelly-like mass. Any excess of
water may be poured off, and the gum is then ready for use.
The larger crabs and lobsters contain such an amount of soft tissue
within that it becomes absolutely necessary to clear them in order to
avoid the unpleasant and destructive effects of decomposition.
[Illustration: FIG. 43.--SMALL CRAB MOUNTED ON A CARD]
In the case of lobsters the abdomen should be removed from the large
cephalo-thorax by cutting through the connecting membrane with a sharp
knife. The soft portions of both halves of the body are then raked out
by means of a piece of wire flattened and bent at one end, and the
interior cleaned with the aid of a rather stiff bottle-brush. The large
claws are then removed by cutting through the membrane that unites them
with the legs, and these are cleared in a similar manner. The different
parts are next laid out to dry on blotting-paper, with the various
appendages attached to the body arranged just as in life; and, finally,
when all parts are quite dry, both within and without, the separated
parts are reattached by means of some kind of cement. For this purpose a
solution of gelatine in acetic acid is much better than gum tragacanth,
as it has a far greater holding power, and this is necessary when we
require to unite rather large structures with but small surfaces in
contact.
Large crabs are to be dealt with much in the same manner, but, instead
of removing the abdomen only, which, in the crab, is usually very small
and doubled under the thorax, the whole carapace--the large shell that
covers the entire upper surface of the body--should be lifted off, and
replaced again after the specimen has been cleaned and dried.
MARINE SHELLS &C.
We have previously dealt with the preservation of the shell-less
molluscs, and the soft bodies of the shelled species when such are
required, so we will now see what should be done with the shells.
Numerous shells are often to be found on the sea beach--shells that have
been washed in by the breakers, and from which the animal contents have
disappeared, either by the natural process of decay, aided by the action
of the waves, or by the ravages of the voracious or carrion-eating
denizens of the sea; and although these shells are rarely perfect,
having been tossed about among the other material of the beach, yet we
occasionally find here the most perfect specimens of both univalve and
bivalve shells in such a condition that they are ready for the cabinet,
and these often include species that are seldom found between the
tide-marks, or that are otherwise difficult to obtain.
However, the shell-collector must not rely on such specimens as these
for the purpose of making up his stock, but must search out the living
molluscs in their habitats and prepare the shells as required.
The molluscs collected for this purpose are immersed in boiling water
for a short time, and the animal then removed from the shell. In the
case of bivalves it will generally be found that the hot water has
caused the muscles of the animal to separate from the valves to which
they were attached, or, if not, they have been so far softened that they
are easily detached, while it does not destroy the ligament by means of
which the valves are held together at the hinge; but the univalve
molluscs must be removed from their shells by means of a bent pin or
wire. In the latter instance care must be taken to extract the whole of
the body of the animal, otherwise the remaining portion will decompose
within the shell, giving rise to the noxious products of natural decay.
The univalves have now simply to be placed mouth downwards on
blotting-paper to drain and dry, when they are ready for the cabinet.
If, however, they include those species, like the periwinkles and
whelks, that close their shells by means of a horny lid (_operculum_)
when they draw in their bodies, these lids should be removed from the
animal and attached to their proper places in the mouth of the shell.
The best way to accomplish this is to pack the dry shells with cotton
wool, and then fasten the opercula to the wool by means of a little gum
tragacanth or acetic glue.
Bivalve shells should, as a rule, be closed while the ligament is still
supple, and kept closed until it is quite dry, when the valves will
remain together just in the position they assume when pulled together by
the living animal. The shells of the larger species may be conveniently
kept closed during the drying of the ligament by means of thread tied
round them, but the very small ones are best held together by means of a
delicate spring made by bending fine brass wire into the form shown in
fig. 44.
[Illustration: FIG. 44.--SPRING FOR HOLDING TOGETHER SMALL BIVALVE
SHELLS]
There are many features connected with the internal structure and
surface of the shells of molluscs that are quite as interesting and
instructive as those exhibited externally; hence a collection of the
shells intended for future study should display internal as well as
external characteristics. Thus, some of the spiral univalve shells may
be ground down on an ordinary grindstone in order to display the central
pillar (the _columella_) and the winding cavity that surrounds it, while
others, such as the cowries, may be ground transversely to show the
widely different character of the interior. Bivalve shells, too, may be
arranged with the valves wide open for the study of the pearly layer,
the lines of growth, the scars which mark the positions of the muscles
that were attached to the shell, and the teeth which are so wonderfully
formed in some species.
Some collectors make it a rule to thoroughly clean all the shells in
their collection, but this, we think, is a great mistake; for when this
is done many of the specimens display an aspect that is but seldom
observed in nature. Many shells, and especially those usually obtained
in deep water, are almost always covered with various forms of both
animal and vegetable growth, and it is advisable to display these in a
collection, not only because they determine the general natural
appearance, but also because these growths are in themselves very
interesting objects. Further, it is a most interesting study to inquire
into the possible advantages of these external growths to the
inhabitants of the shells, and _vice versâ_--a study to which we shall
refer again in certain chapters devoted to the description of the
animals concerned.
But there is no reason whatever why some of the _duplicate_ specimens
should not be cleaned by means of a suitable brush, with or without the
use of dilute hydrochloric acid (spirits of salt), or even polished, in
some few cases, to show the beautiful colours so often exhibited when
the surface layer has been removed. This, however, should be done
somewhat sparingly, thus giving the greater prominence to the exhibition
of those appearances most commonly displayed by the shells as we find
them on the beach or dredge them from the sea.
Very small and delicate shells may be mounted on cards, as suggested for
other objects; but, as a rule, the specimens are best displayed by
simply placing them on a layer of cotton wool in shallow boxes of
convenient size.
The number of insects that may be described as truly marine is so small
that their preservation is not likely to form an important part of the
work of the sea-side naturalist; and even though a considerable number
of species exhibit a decided partiality for the coast, living either on
the beach or the cliffs, the study of these is more generally the work
of the entomologist. For this reason, and partly because we have already
given full instructions for the setting and mounting of insects in a
former work of this series, we consider a repetition inadmissible here.
The subject of the preservation of fishes, also, will require but few
words. There is no satisfactory method of preserving these in a dry
state, though we often meet with certain thin-bodied species, such as
the pipe-fish, that have been preserved by simply drying them in the
sun. Fishes should be placed in dilute spirit, or in one of the other
liquids recommended, but a change of fluid will always be necessary
after a time, and also frequently the gentle application of a brush to
remove coagulated slime from the surface of the scales.
The great drawbacks in the way of preserving a collection of fishes are
the expense of the specimen jars, and the large amount of space required
for storing the specimens. Of course the former difficulty can be
overcome by substituting ordinary wide-mouthed bottles in the place of
the anatomical jars, while the latter can be avoided to a considerable
extent by limiting the collection to small species, and to small
specimens of the larger species. If this is done, it is surprising what
a large number of fishes can be satisfactorily stored in bottles of only
a few ounces’ capacity.
FLOWERS AND SEA WEEDS
The apparatus required for the preservation of the wild flowers of our
cliffs, and the sea weeds, consists of a quantity of blotting paper or
other thick absorbent paper cut to a convenient size, a few thin boards
and a few pieces of calico of the same size, some heavy weights, and
several sheets of drawing paper.
The wild flowers are arranged on the sheets of absorbent paper while
still fresh, care being taken to display the principal parts to the best
advantage. They are then placed in a single pile, with a few extra
sheets of absorbent paper between each two specimens to facilitate the
drying, boards at the bottom and top as well as at equal distances in
the midst of the pile, and the weights on the top of the whole.
The natural colours of leaves and flowers are not very often preserved
satisfactorily, but the best results are obtained when the drying
process proceeds most rapidly. Hence, if the press contains any
specimens of a succulent or sappy nature, they should be taken out after
the first day or two, and then replaced with a fresh supply of dry
paper.
The flowers must be left in the press until quite dry, and they may then
be mounted on sheets of drawing paper, by fixing them with a little gum
tragacanth, or by narrow strips of gummed paper passing over their
stems.
Some collectors prefer simply placing their botanical specimens inside
double sheets of drawing paper, not fastening them at all, and there is
much to be said in favour of this, especially as it allows the specimens
to be examined on both sides; and even when they _are_ fastened to the
paper double sheets are much to be preferred, for the specimens are not
then so liable to be damaged by friction when being turned over,
especially when the names are written on the outside of each sheet.
The larger sea-weeds may be dried in the same manner, though it is a
good plan to absorb the greater part of the moisture they contain by
pressing them between pieces of calico previous to placing them in the
ordinary press. It should be observed, however, that many sea-weeds
exude a certain amount of glutinous substance that makes them adhere to
the paper between which they are dried, while they do not so freely
adhere to calico. These should be partially dried in the calico press,
and then laid on the paper on which they are to be finally mounted, and
re-pressed with a piece of dry calico on the top of each specimen.
Many of the smaller weeds may be treated in the manner just described,
but the more delicate species require to be dealt with as
follows:--Place each in a large, shallow vessel of water, and move it
about, if necessary, to cause its delicate fronds to assume that
graceful form so characteristic of the algæ of our rock pools. Then
immerse the sheet of paper on which the weed is to be finally mounted,
and slowly raise the specimen out of the water, on the paper, without
disturbing the arrangement of the fronds. If it is found necessary to
rearrange any of the fronds, it may be done by means of a wet camel-hair
brush. Now lay the specimen on calico or absorbent paper, placed on a
sloping board, to drain; and, after the greater part of the moisture has
disappeared by draining and evaporation, transfer the specimen to the
press with a piece of dry calico immediately over it. All are dealt with
in turn in the manner described, and allowed to remain in the press
until perfectly dry, when it will be found that the majority of them
have become firmly attached to the mount, and require nothing but the
label to fit them for the herbarium.
Sea-weed collectors often make the great mistake of pressing tufts that
are far too dense to admit of the structural characters being
satisfactorily examined. To avoid this fault, it will often be necessary
to divide the clusters collected so that the forms of their fronds may
be more readily observed.
The calcareous corallines may be pressed in the same way as the other
algæ, but very pretty tufts of these, having much the appearance of the
living plant, may be obtained by simply suspending them until thoroughly
dry; though, of course, specimens so prepared must not be submitted to
pressure after they are dry, being then so brittle that they are easily
broken to pieces.
The hard framework of these interesting corallines is composed
principally of carbonate of lime, a mineral substance that dissolves
freely in hydrochloric acid (spirits of salt). Thus, if we place a tuft
of coralline in this acid, which should be considerably diluted with
water, the calcareous skeleton immediately begins to dissolve, with the
evolution of minute bubbles of carbonic acid gas; and after a short
time, the end of which is denoted by the absence of any further
bubbling, nothing remains but the vegetable matter, now rendered soft
and pliant. A decalcified specimen of coralline may be pressed and
dried, and then mounted beside the plant in its natural condition for
comparison; and the true appearance of the vegetable structure may also
be retained, and in a far more satisfactory manner, by preserving a
portion of the specimen in dilute spirit.
Finally, it may be observed that many sea-weeds, like wild flowers, do
not retain their natural forms and colours when preserved dry. They are
spoilt by the pressure applied, or become so shrivelled and discoloured
in the drying as to be but sorry representatives of the beautifully
tinted and graceful clothing of the rocks of the coast. But many of
those that suffer most in appearance when dried may be made to retain
all their natural beauty by preserving them in a fluid; and it is most
important that this should be remembered by all who desire to study the
weeds at home, and particularly by those who possess a microscope, and
wish to search into the minute structure of marine algæ. Our own plan is
to keep not only the dried specimens for the purpose of studying the
general characters and classification of the algæ, but also to keep a
few large bottles--stock bottles--filled with weeds of all kinds in a
preservative fluid. These latter are exceedingly useful at times, and
are frequently brought into requisition for close inspection, with or
without the microscope. Small pieces may be detached for microscopic
examination when required, and sections may be cut either for temporary
or permanent mounting just as well as from living specimens, such
sections showing all the details of structure exhibited by the living
plant.
THE MUSEUM
One of the greatest difficulties besetting the young collector lies in
the choice and construction of the cabinet or other store-house for the
accommodation of the specimens that accumulate as time advances.
Of course, when expense is a matter of no great consideration, a visit
to the nearest public or private museum to see the manner in which the
specimens are housed, followed by an order to a cabinet-maker, will set
the matter right in a short time; but it is probable that the majority
of our readers are unable to fit up their museum in this luxurious
style, and will either have to construct their own cabinets and
store-boxes or to purchase cheap substitutes for them.
Where one has the mechanical ability, and the time to spare, the
construction of a cabinet with the required number of drawers may be
undertaken, and there is no better form of store than this. The whole
should be made of well-seasoned wood, and the drawers should vary in
depth according to the size of the specimens they are to contain. Some
of these drawers may be lined with sheet cork, and the cork covered with
white paper or a thin layer of cotton wool. This will enable some of the
specimens to be fixed in their places by means of pins. As a rule,
however, no pins will be required, and the specimens will be most
conveniently arranged in shallow cardboard boxes, placed in rows in the
drawer, a little cotton wool covering the bottom of each.
Failing the usual cabinet, the specimens may be stored in shallow trays
or boxes, or even in the little cardboard cabinets so often sold for
storing stationery &c. The best and cheapest things of this kind we have
ever met with are the little cabinets, each containing either six or
twelve drawers, made by Macdonald & Co., of Temple Row, Birmingham. By
the use of such as these the specimens may be neatly stored away, and
additions to match may always be made as the collection increases in
magnitude.
The specimens should all be classified according to their positions in
the animal or vegetable world, and accompanied by labels giving the name
of species and genus, together with localities, habitats, &c. The
outlines of classification may be studied from the later chapters of
this work, in which the common objects of the sea shore are described in
their scientific order, beginning with the lowest sub-kingdoms and
classes; and further, it will be observed that the sub-kingdoms are
divided into classes, the classes into orders, orders into families,
families into genera, and that the genera contain a smaller or larger
number of closely allied species.
The collection must be kept in a perfectly dry place, otherwise many of
the specimens will be liable to develop moulds, and this will, of
course, quite spoil their appearance. It is almost sure to be attacked
by mites and other animal pests unless some means be taken to prevent
their intrusion.
As regards the latter, it is well to know that it is far easier to
prevent the intrusion of small animal pests than it is to exterminate
them after they have once found an entrance; and so, from the very
commencement of the formation of the collection, all drawers and boxes
should be charged with some substance that is objectionable, if not
fatal, to them. Small lumps of naphthaline (albo-carbon) put into the
various compartments, and renewed occasionally as they disappear by
evaporation, will generally suffice to prevent the entrance of all
pests, but this substance is not effectual as an insecticide for the
purpose of killing them after they are in.
Perhaps the best of all insecticides is the corrosive sublimate already
mentioned, and this may be applied to any animal or vegetable object
that is capable of providing food for museum pests, and it is difficult
to find such an object on which they will not feed.
Many of the specimens that find a place in a museum have been
temporarily preserved in spirit previous to being dried, and if a little
corrosive sublimate was dissolved in this spirit, the specimens will
have been rendered perfectly free from all attacks of marauders, since
the spirit will have saturated the whole object, carrying with it the
dissolved poison.
Most of the specimens that have not been treated by the above method
would not suffer from a short immersion in spirit containing the
corrosive sublimate; but in cases where it is considered inexpedient to
do this, the same liquid may be applied to them by means of a soft
brush. In this way even the dried botanical specimens may be rendered
perfectly secure from attacks.