The Sea Shore

by William S. Furneaux

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 Goadby’s fluid, 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.