Tour the Smithsonian After its First Fifty Years

"The collection of marine invertebrates under the direction of the curator, Mr. Richard Rathbun, is rapidly being reduced to order; the averages of many years fast being made up. This has been a task of considerable magnitude, from the fact that in the decade ending 1880.

very little attention had been paid to this department, and that the best part of the material was destroyed in the burning of the Chicago Academy of Sciences. . . . Very little, therefore, has been done in the development of the exhibition series, and the chief activity has been in the store- rooms. . . The coral collection, as well as part of the echinoderms and sponges, have been mounted on ebonized tablets, and the experiments which have been made in arranging these in cases with maroon backgrounds indicate that the west hall when arranged will be one of the most beautiful and attractive in the Museum."

The "west hall" referred to in the above-given extract from an annual report, is in the old Smithsonian building, where now is made one of the finest displays in the world, of sponges, corals, echinoderms, worms and crustacea, largely dredged from the deep sea.

The first specimens to be examined are those lowest in the scale of organization, whence we may progress to higher ranks: these are the sponges. They are grouped together and mounted upon tablets of dark color, so as to show in most cases both the natural (dried) sponge and the skeleton after it has been prepared for commerce. The greater number belong to Floridan waters.

The sponge animals exist in all tropical oceans and somewhat in temperate seas. They are particularly abundant in the Mediterranean and the Red sea, Malayan waters, and in the Gulf of Mexico and the Caribbean sea whence they are gathered for commerce. They are usually considered to be plants by the fishermen, and it is only recently that all naturalists have conceded them to be egg- bearing animals probably the lowest of all that class. Their structure is very simple, and they feed, by absorption, upon the nutriment floating invisible in the sea- water. This is assimilated not only by the outside surface, but from currents admitted through innumerable minute channels which radiate to the surface from one or more large interior canals, whence, by contractions of the body, the waste- water is expelled in a strong, palpitating current. Sponges are never left uncovered by the tide, and therefore so far as we can see, there is no break in their eternal feasting. If a sponge contracts dyspepsia in consequence, it must be a most trying disease; for instead of simply "being the possessor of a diabolical arrangement called a stomach," as poor Carlyle was, it has nearly nothing else. Any wrinkle or follicle in the soft external covering of the sponge offering a lodgment for an alga- spore, a shrimp's egg, a bacteria germ or some other such microscopic and etherial morsel, straightway becomes a digesting point, and assimilates and rejects nourishment and waste from the captive tidbit. Thus instead of one, a sponge may have half-a-hundred stomachs in active operation at one moment.

The stability of the sponge is due to its possessing internal supports answering the purpose of a skeleton, since it forms a framework upon which the nearly structureless, jelly- like matter, called sarcode, which constitutes the living and assimilating tissue of the animal, is built up and kept in shape. In some sponges, however, this skeleton is absent, in others hardly perceptible; in others it consists of silicious or calcareous spicules unattached to each other; or a wonderfully delicate network of glass threads exists, as in Hyalina: while in many species the skeleton branches form a tough central "root" in an infinity of flexible twigs, interlacements and foliations,which cause the general shape not only but almost the exact dimensions of the original growth to he preserved after the animal is dead and all the "flesh" has disappeared. Of this character are the commercial sorts, exhibited by McKesson & Robbins, New York.

Besides general information on sponges to be obtained from the "Standard" and other general works on natural history, a most commendable little book has been written about the commerc al species by Prof. Alpheus Hyatt, in the Boston Society of Natural History's series of "Guides for Science Teaching," No. III.

The next group comprises the Hydroids, Corals and Alcynoids, the great variety and beauty of the forms of which are well shown in this magnificent collection, the equal of which probably does not exist in the world, and which is especially valuable to scientific men from the fact that it contains a great number of specimens collected by Dana on the Wilkes Exploring Expedition, and first described in his splendid folio, printed by the government.

Coral is the product of animals called polyps, which belong to the division of the animal kingdom termed Radiate, because all the organs radiate from the center toward the periphery. The three classes of Radiates, beginning with the lowest are: 1. Polyps, or sea-anemones and corals, 2. Jelly-fishes; and 3. Echinoderms, or star-fishes, sea-urchins, trepangs, etc. "In the polyps the plan is executed in the simplest manner, the body consists of a sac, the sides of which are folded inward at regular intervals, from top to bottom, so as to divide it by vertical radiating partitions converging from the periphery toward the center. These folds do not meet in the center, but leave an open space, which is the main cavity of the body. This open space, however, occupies only the lower part of the body, for in the upper there is a second sac hanging a certain distance within the first. This inner sac has an aperture in the bottom through which whatever enters it passes into the main cavity of the body. A central opening in the top forms a kind of mouth, around which are radiating tentacles connecting with the open chambers formed by the partitions within (Fig. 9). The second class is that of the jelly-fishes or acalephs (Fig. 10); and here the same plan is carried out in the form of a hemispherical gelatinous disk, the digestive cavity being hollowed, or, as it were, scooped, out of the substance of the body. [No way of preserving the watery jelly- fishes for exhibition has been invented], . . The third and highest class includes the star-fishes, sea- urchins, and holothurians or bêches-de-mer. The radiation is equally distinct in each of these, but here again the mode of execution differs from that of the other two classes. The internal cavity and the radiating tubes, instead of being connected with the outer wall of the body as in polyps, or hollowed out of the substance of the body as in jelly- fishes, are here inclosed within independent walls of their own (Fig. 11), quite distinct from the walls of the body." -L. AGASSIZ, Methods of Study in Natural History.

The coral animals belong to the polyp class. They include a great number of species, and nearly all grow in clusters, which start from a single animal, born from an egg, and swimming freely for a time before it settles down and attaches itself to some fixed support. Hard particles of lime now begin to be deposited in the wall of the body, and in all the partitions, until the whole animal has a solid frame, a horizontal cross- section of which resembles a wheel without an hub. The only parts which remain soft are the summit, the mouth, the fringe of tentacles about it, and the stomach within. When this first animal has reached its maturity, offspring begin to grow from its sides, by a process which resembles budding, and thus a large colony rapidly spreads itself, all the individuals of which are connected with one another by openings at the base of the body, so that the nourishment imbibed by one circulates through his neighbor's system and contributes to feed the whole colony. It is the hard, limy secretion within these polyps which becomes "coral,"- their solid frames or skeletons -and each oval or star- shaped pit represents what was one animal. Out of these pits they could expand their soft parts, or the tentacles could be drawn almost within, but the polyp could no more separate itself from its coral frame than a turtle could leave its shell, or we dispense with our bones!

A glance at the wall- cases will show how greatly corals differ in size and mode of growth: while some never attain more than trifling dimensions, others widen into reefs and islands on which cities are founded.

On foundations laid in pretty deep water by the solid masses of Astrea, arise the reefs which in circular form make the atols of the Pacific, or in straight banks act as barriers for continental shores. But, when they have brought the wall so high that they have not more than six fathoms of water above them, this sort of coral ceases to grow. "They have, however, prepared a fitting surface for different kinds of corals that could not live in the depths from which the astreans have come, but find their genial home nearer the surface; such a home being made ready for them by their predecessors, they now establish themselves on the top of the coral walls and continue its growth for a certain time. These are the mean Brinas, or the so-called brain- corals, and the porites. . . . But these also have their bounds within the sea; they in their turn reach the limit beyond which they are forbidden by the laws of their nature to pass, and there they also pause. But the coral wall continues its steady progress; for here the lighter kinds set in, -the madrepores, the millepores, and a great variety of sea -fans and corallines, and the reef is crowned at last with a many -colored shrubbery of low, feathery growth."

The authorities on corals and coral reefs for popular reading are Darwin's "Voyage of a Naturalist" (Harper's) and his "Coral Islands;" Dana's "Corals and Coral Reefs," Forbes's "Naturalist's Wanderings" (Harper's); the books of Agassiz and of his wife; and the Reports of the U. S. Fish Commissioners.

The next class is that of the Echinoderms or spiny- skinned animals. The form of lowest rank among these is that of the sea- urchin or seaegg (Echinus,- which is a more or less globular box of hard materials covered with spines, that move about somewhat at the control of the animal, whose mouth is a small aperture on the under side , amid the spines, and whose soft parts all hang within the limy case. Echini live on rocky shores, and also at great depths. They form an important part of the food of many coast savages. One of the most plentiful and characteristic fossils of the Silurian age was the crinoid- a precursor of the sea-urchin, which was mounted upon a waving stalk and had many arms covered with calcareous plates.

The ordinary star-fish, well represented by specimens, attains importance, apart from scientific interest, by his ravages upon our oyster beds. He is fully described in Ingersoll's "Monograph of the Oyster Industries," published by the Tenth Census; and in his "Country Cousins." Verrill's "Invertebrates of Vineyard Sound" (Rept. U. S. Fish Com., I874,) names all the New England species, as also the other marine invertebrates of the northern Atlantic coast. Certain star-fishes or "brittle-stars" , having long, slender and "snaky" arms are called ophiurans, others, where every arm is so ramified as to seem like little bushes, are termed "basket-fish."

A third class includes the Holothuria, which the English call sea-cucumbers, the French beches-de-mer, and the Malays trepangs.

"The holothurians have not the hard brittle surface of the other echinoderms; on the contrary their envelope is tough and leathery capable of great contraction and dilatation. No idea can be formed of the beauty of these animals, either from dried specimens or from those preserved in alcohol. Of course, in either; case they lose their color, become shrunken, and the movable appendages about the mouth shrivel up . . , I have seen such an animal, when first thrown into a tank of sea- water, remain for a while closely contracted, looking like a soft crimson ball. Slowly, almost imperceptibly, as it becomes accustomed to its new position, it begms to elongate; the fringes creep softly out, spreading gradually all their ramifications, till one end of the animal seems crowned with feathery crimson seaweeds of the most delicate tracery."

The Marine Worms, living in the sand of the beaches, the mud of the deeper bottom or parasitically upon or within the bodies of sea animals, also come into this department, another section of which is devoted to the Crustacea (lobsters, crabs, shrimps, etc., of great economic importance as food), besides a host of minute swimming forms, fed upon by the fishes, or of service as the scavengers of the sea.

Allied to this is the Department of Fossil Invertebrates, wherein an enormous bulk of material has been accumulated by the western surveying expeditions and by the labors of private geologists in the eastern part of the Union; nor is this accumulation likely to cease. Many scientific men of prominence have contributed labor and skill toward perfecting the arrangement and condition for study of this huge collection of the fossils of the lower forms of life, which have formed the basis for the volumes of Profs. F. B. Meek, F. V. Hayden, James Hall, C. A. White, and others in America and Europe. While the bulk of the material comes from the rocks of the interior and western part of the United States, the fossiliferous strata of the east are splendidly represented by the first duplicates of the Hall collection, made by the state geologist of New York , a collection which has been the admiration of paleontologists for many years, and which is now the property of the American Museum of Natural History in New York city. The invertebrate fossils of the southern states are also fairly represented; while the cretaceous and tertiary ages of Europe are excellently portrayed by the acquisitions of M. J. J. M. de Morgan, of Paris, received during 1881.

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