ARTICLE XIV.

FOURTH DIVISION, SECTION 4.

ZOOLOGY.

BY RICHARD OWEN, Esq.

Instructions for Collecting and Preserving Animals.

As water is the element in which the greater number of the classes of animals exist, and as the sea is the scene of such existence and the field of research which will be most commonly presented to those for whom the following instructions for collecting and preserving animals have been drawn up, they will commence with the marine species and the lowest forms of animal life.

ALGE, SPONGES, CORALLINES, and CORALS.

The line of demarcation between the vegetable and animal kingdoms is so obscurely marked in the lowly organized marine species, and the modes of collecting and preserving these are so similar, that the kindred groups above-named are associated together as the subjects of the following remarks.

Algae, commonly called seaweeds, may be divided, for the convenience of the collector, into three kinds, according to their colour ::

1. Olive-coloured (Fuci); generally of large size and leathery texture, rarely gelatinous; usually laminate or leafy, rarely filamentous or thready.

2. Red-coloured (Florideœ); firm, fleshy, or gelatinous ; usually filamentous, sometimes membranaceous.

3. Green (Chlorosperms); membranaceous or filamentous; rarely horny.

Sponges are bodies usually adherent in irregular or amorphous masses, rarely in the form of hollow reticulate cones; they are composed of a soft, jelly-like tissue, supported by siliceous or calcareous spiculæ, or by horny filaments. They are divided accordingly into horny or "keratose," flinty or "siliceous," and limey or "calcareous" sponges. Their soft organic substance is commonly diffluent, and drops from the firmer basis when removed from the water, or it is easily washed away. It exhibits no sign of sensibility; no contraction or retraction when touched or otherwise stimulated. The evidence of life is afforded by the flow of currents of water through canals, entering by pores and escaping by larger orifices: an appearance of animal life is given to both algae and sponges by the locomotion of the sporules or gemmules.

Corallines are plants coated with a calcareous covering, either red or green when fresh, becoming white and brittle on exposure to the air.

Corals, though called "zoophytes," are true animals; the currents which permeate them enter by mouths," always provided with a crown of feelers or seizers, called tentacles, and communicating with digestive sacs or

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stomachs," into which the pores of the nutrient canals open. The tentaculated mouths are called " polypes." Their fleshy tissue, as well as that which connects them. together into an organic whole when the coral is compound or has more than one mouth, is "sensitive," or retracts and shrinks when touched. For the purposes of the collector corals may be divided into the "fleshy" (Polypi carnosi), in which the flesh has no firm supporting part; the "horny" or "flexible," usually having this supporting substance as an external tube; and the calcareous," in which the supporting substance, composed of carbonate of lime, is usually covered by the animal matter or flesh, forming an internal skeleton, usually of one piece, rarely jointed.

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The above-defined classes of organized beings, which all present, more or less, the habit" or outward form of plants, are found from the extreme of high-water mark to the depth of from 50 to 100 fathoms. Living algæ rarely descend below 50 fathoms, but corals of the genera Lepralia, Retepora, and Hornera have been dredged up from 270 fathoms, and fragments of dead coral from 400 fathoms.* Specimens within the reach of the tide are to be collected at low water, especially of spring tides: the most interesting species occur at the verge of low-water mark. Those that dwell at greater depths must be sought by dredging, or by dragging after a boat an iron cross furnished with numerous strong hooks. One or more strong glass bottles with wide mouths, or a hand-basket lined with japanned tin, should be provided for the purpose of bringing on board the smaller and more delicate species in sea-water, and they should be kept in it, the " Floridea" more especially, until they can be arranged for drying, or other modes of permanent preservation can be attended to.

In collecting algae, corallines, or the branched, horny, or calcareous corals, care should be taken to bring the entire specimen with its base or root. With respect to the coarser algæ, it is merely requisite, for the purpose of transmission, to spread the specimens immediately on being brought fresh from the sea, without previous washing, in an airy situation to dry, but not to expose them to too powerful a sun: if turned over a few times they will dry very rapidly. When thoroughly dried they may be packed loosely in paper bags or boxes, and will require only to be remoistened and properly pressed, in order to make cabinet specimens. For the purpose of transmission it is better not to wash the specimens in fresh-water previous to drying, as the salt they contain tends both to preserve them and to keep them pliable, and more ready to imbibe water on reimmersion. With respect to the delicate alge: The collector should have two or three flat dishes, one of which

Captain Sir James C Ross, Antarctic Voyage,' Appendix, No. IV.

is to be filled with salt water and two with fresh; in the first of these the specimens are to be rinsed and pruned, to get rid of any dirt or parasites, or other extraneous matter; they are then to be floated in one of the dishes of fresh water for a few minutes, care being taken not to leave them too long in this medium, and then one by one removed to the third dish, and a piece of white paper, of the size suited to that of each specimen, is to be introduced underneath it. The paper is to be carefully brought to the surface of the water, the specimen remaining displayed upon it, with the help of a pair of forceps or a porcupine's quill, or any finepointed instrument; and it is then to be gently drawn out of the water, keeping the specimen displayed. These wet papers, with their specimens, are then placed between sheets of soft soaking-paper, and put under pressure, and in most cases the specimen adheres in drying to the paper on which it is laid out. Care must be taken to prevent the blotting-paper sticking to the specimens and destroying them. Frequent changes of drying-paper (once in six hours), and cotton rags laid over the specimens, are the best preservatives. The collector should have at hand four or five dozen pieces of unglazed thin calico (such as sells for 2d. or 3d. per yard), each piece about eighteen inches long and twelve inches wide, one of which, with two or three sheets of paper, should be laid over every sheet of specimens as it is put in the press. These cloths are only required in the first two or three changes of drying-papers; for, once the specimen has begun to dry, it will adhere to the paper on which it has been floated in preference to the blotting-paper laid over it." *

For dried specimens of corallines, corals, and sponges, it is advisable to soak the specimen for a time in fresh water before drying. They may then be packed among the rough-dried seaweeds in boxes; but the more delicate specimens should be placed in separate chip-boxes with

cotton.

* Dr. Harvey, in Mr. Ball's Report on the Dublin University Museum,' p. 3.

With regard to corals, &c., it must be remembered that dried specimens are but the skeletons of those animals, and that only the "horny" and "calcareous" species can be so preserved. The "fleshy" kinds, commonly known as "polypes," "sea-anemones," or animal-flowers," must be preserved entire in alcohol, glycerine, or saline-solution, and of the latter the following (No. I. of Goadby's recipes) has been found successful :—

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In order to preserve the specimens expanded they should be removed and placed alive in a dish of sea-water; and when they have protruded and expanded their tentacles, the solution should be slowly and quietly added to the seawater, when the animal may be killed and fixed in its expanded state. So prepared, the specimens should be transferred to a bottle of fresh solution.

In like manner the minute polypes of the flexible or horny corals may be preserved protruded from their cells and expanded. If a small piece of corrosive sublimate is put into the vessel of sea-water containing such living polypes, it will kill or paralyse them when protruded, as it slowly dissolves; but they must be removed as soon as they have lost their power of retraction, otherwise their tissue is rendered fragile or is decomposed. The polypes or animal part of the calcareous kinds, called "madrepores," "millepores," "fungiæ," "red coral," "gorgoniæ," &c., require for their preservation, in connexion with their supporting basis, the following solution (No. II.):