THE shores of the Phillippine Islands yield the exquisite object which has been well called Venus' Flower-basket, and which is known to science as a sponge, to which the name Euplectella speciosa has been appropriately given. The ordinary observer, familiar only with the sponges in domestic use, or with somewhat similar structures of branched and finger-like forms frequently found on the beaches of frequented watering-places, will be much surprised at finding the name of sponge applied to the elaborate network of the Euplectella, which looks like an exceedingly delicate fabric of some such material as biscuit china, and which might readily be taken for a coral, although an investigation of its structure would show that it was entirely different from any polyp formation. Our engraving represents one of the finest of the British Museum specimens, but the following description is chiefly taken from a specimen in the writer's possession, which he was able, at no small risk of its destruction, to examine more carefully than could be effected in any public institution.

The naturalist groups together a number of bodies varying considerably in appearance, in structure, and in material, under the designation sponge. Sponges are, however, all alike in certain general characters. They all consist of a living mass of delicate gelatinous fleshy material, called sarcode, and of a framework or skeleton, with certain appendages, which is either horny (keratose), calcareous, or silicious. The common toilet sponge belongs to the horny series, and the Venus' Flower-basket is the most exquisite of the silicious.

Whatever may be the form of the sponge skeleton, or of the spicules of various shapes which belong to it, or are embedded in the soft flesh, it is by, and in, that flesh, that they

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are all produced. In the silicious series, the glossy threads, or spicules, have a very small channel running through them, and they are formed, not in one piece, as a glass-blower spins his so-called hair, but by a series of additions, arranged as concentric layers, each layer being a deposit from the living sarcode.

In the Euplectella the structure bears, at first sight, an aspect of basket-work, and imagination might picture the young mermaidens varying their legendary occupation of combing their sea-green hair, by employing their finny fingers in weaving together the glittering threads of which it is composed. It is, however, not a product of any mechanical plaiting, but of organic life and growth, and a microscopic examination at once distinguishes it from any structure put together by the intertwisting of separate fibres. To view the Euplectella under the microscope without breaking it to pieces requires a good deal of trouble, and a little skill; but it is very advisable to examine it in an uninjured condition, as well as to study details of structure in fragments that may be broken off. From the size of the Euplectella it cannot be examined if laid across the stage of Ross's large and fine microscope, as that instrument, so admirable in most other particulars, has not enough rack-room to raise a low-power object-glass to the focussing height above so thick an object. Smith and Beck's pattern is superior in this respect, and in our investigation we employed both. To view the Euplectella under the Ross binocular, we rigged up a temporary stage of card under the brass stage of the instrument, and then got on pretty well with three inch, and one and a half inch powers. Further examination was made with a monocular Smith and Beck, the delicate sponge being placed across the stage, and supported by a box at each end.

A good specimen, fully grown, of the Venus' Flower-basket will be rather more than a foot long, and about two inches in diameter at its widest end. It takes, as our plate shows, the curve, and somewhat the form, of a cornucopia. At the base it is covered with a quantity of silicious hairs, part of which the natives have a knack of removing before sending it to Europe. The natural position of this sponge is upright, and it probably grows on a soft sea-bed. At nearly equal distances, say from one-eighth to three-sixteenths of an inch apart, vertical bundles of silicious threads rise from the base, and are continued to the top of the structure, and at right angles to these we observe a series of horizontal rows, crossing the former and giving rise to square meshes of considerable regularity. Slanting fibres cross the corners of these squares, and give a more or less rounded appearance to the central apertures;

while from near the base to the top, elegant frills or furbelows rise at their intervals, composed of interlacing fibres. These frills rise gently from the general surface, and stand out from it to a distance of from one to three-eighths of an inch. They have a general disposition to form diagonals to the square meshes, which they cross in graceful undulations. They are wider at the base than at the top, and no doubt materially strengthen the delicate structure which they adorn. In the writer's specimen they are in two sets, one at right angles to the other, and must be regarded as beautiful instances of decoration, arising out of a construction evidently intended for the useful purpose of increasing the resisting power of an extremely light framework.

The first aspect of the Euplectella, under low magnification, leads to the notion that the vertical and horizontal bundles of silicious threads are simple cylinders, more or less closely packed together; but a closer investigation shows that they are more complex. It is common to find two or more, as it were, soldered together, and the external ones, especially, frequently throw out branches and prolongations, which form junctions with other threads far and near. junctions are sometimes smooth, and at others marked by slight rounded prominences. A thread will often proceed for some distance as a simple cylinder, and then divide, either with a bold furcation, or forming two nearly parallel threads, joined at intervals by cross pieces. Many instances may be observed of little projections from such threads looking at each

These

FIG. 1.-Portion of Network of Skeleton of Euplectella speciosa, magnified.

other across the narrow gulf, but not quite meeting, as if their growth were arrested or incomplete. The threads that take

slanting directions across the corners of the square meshes are much branched and forked, and frequently spicules with cross heads may be seen. There are also numerous jagged threads, not belonging to the main structure, but appended to it, and often terminating in a knot of recurved hooks, like certain walking-sticks cut from thorns. Spicules, of a more elaborate pattern, probably belong to the sarcode, are perhaps more frequent in rough dingy-looking specimens than in those which have been bleached and cleaned.

Fig. 1 (p.163.) represents a portion of the net-work, reduced one-half from the original drawing, made with a magnification of about 17, and selected to represent the general character of the threads crossing the square meshes. In this sketch the horizontal and vertical threads are depicted as simple cylinders, which appearance they often present under low powers for considerable distances.

Fig. 2 is a reduction from a sketch made under higher magnification (x 40), from a portion that well shows the way in

FIG 2.-Euplectella.-Magnified portion, showing organic junction of fibre. which fibres from the main bundles form junctions with fibres springing from other parts.

Fig. 3, reduced one-half from a sketch made with magnification of 17, exhibits the structure of the frills or furbelows.

The top of the Euplectella is covered in full-grown specimens, with a network of threads soldered together, and crossing at various angles, making three and four-sided meshes of different sizes.

When single fibres are separated from the Euplectella, they are found to possess a considerable degree of elasticity, in this respect resembling spun glass, and they may be bent, to some extent, without breaking. Holding a fibre in a spirit

FIG 3.-Frill or Furbelow of Euplectella speciosa, magnified.

lamp causes it to split, and fly to pieces, but if the process is carefully managed, and the burnt portion is examined under the microscope, the character of its formation, by the superposition of concentric fibres will be discovered. Likewise, if a number of ends of broken threads be examined, some will be found to exhibit the aspect of a series of tubes, like the draw tubes of a telescope, one entering into the other.

The production of such an exquisite and complicated framework as the Venus' Flower-basket, by precipitation of silex in a film of sarcode, is, in the highest degree curious and instructive. Probably purely chemical laws of precipitation, under certain conditions, combine with those other laws-whatever they may be-which determine the vital processes of the organization.

The base of my specimen has a rounded form, and is shaggy with the white hair-like fibres, amongst which are entangled a mass of minute shells, foraminifera, mud particles, and sundry spicules; but I have not in the base, or anywhere else, found any of the elegant flower-like four-rayed spicules figured by Dr. Bowerbank, and which probably belong to the sarcode, and have been washed away from mine, and other sponges that have been carefully cleaned, in order to exhibit the beauty of the skeleton in a more perfect way.