Now supposing that M. de Blainville is correct in describing the siphon of Spirula to be solid, and upon that fact his argument against Dr. Buckland's theory mainly rests, we cannot allow the inference, which, from observation of a structure for the attachment of the shell to the body in the dibranchiate Spirula, with an internal small shell, concludes that the same structure ought therefore to exist in the tetrabranchiate Nautilus, with its great external shell, to be very sound. Nor is this the kind of argument for which we should have looked in the writings of so eminent a zoologist and comparative anatomist as M. de Blainville.

The following is the theory of M. de Blainville as far as regards Spirula :

Admitting as beyond doubt that the chambers of the shell of Spirula are empty, or at most filled with an aëriform fluid, which appears to be proved à priori, because in fact one cannot conceive how the water could come there, the chambers being closed on all sides, and à posteriori because they are so, even when separated from the animal, which makes these shells constantly float on the surface of the sea, and equally or as well when they form a part of the whole, as M. de Blainville had satisfied himself by experiment on all the individuals brought home by MM. Leclancher and Robert; it seems to M. de Blainville that the re-entry and the contraction of the whole brachiocephalic mass into the case formed by the mantle, as well as the application of the fins against its walls, will be sufficient, by notably diminishing the volume of the animal without at all changing its mass, to counterbalance or even overcome the specific lightness of the air contained in the chambers of the shell, which will again gain the ascendency, when the volume of the animal shall return to its first disposition by the protrusion and expansion of its head and arms. It is certainly thus that the Limnææ and Planorbes [LIMNEANS], act in order to descend to the bottom of the water, for to rise again to its surface they must resort to creeping along solid immersed bodies. With regard to the Spirule, the kind of natatory bladder formed by the aëriferous chambers of their shell can without doubt elevate them to the surface without effort on their part, according to M. de Blainville, and he is even inclined to think that the size of the chambers is, so to speak, measured by the animal instinctively, so that the extent of the vacant space should always be in proportion to the mass of the animal, and floating must be the result, that is to say, there must be a specific gravity less than that of the ambient medium.

Cette manière de voir, cette explication du fait, pour le dire en passant, ne démontrerait-elle pas mieux la sagesse du grand géomètre,' asks M. de Blainville, 'que tout ce que l'on a dit à ce sujet ?'

To this question, we humbly answer, no. Supposing M. de Blainville's theory to be impregnable, the mechanism by which the Nautilus is proved-we write it advisedly-to ascend and descend, is no worse demonstration of the adaptation of means to an end, to say the least of it, than the mode proposed by M. de Blainville.

proportion. In this position it would execute the greatest parts of its functions and its acts; but in order to withdrav itself from danger, it would have the faculty of changing the relation or proportion of the volume to the mass, and of diving more or less; but perhaps without ever reaching the bottom.

Geographical Distribution.—Widely disseminated in the seas of warm climates. [SPONDYLIDE.]

SPI'SULA, Mr. J. E. Gray's name for a genus of Conchifers, founded on Mactra fregilis, and similar species. Ligament subexternal, marginal, not separate from the cartilage. Posterior lateral teeth double and single.

SPITZBERGEN is a group of islands situated nearer to the arctic pole than any other country on the globe. It lies between 76° 30′ and 80° 30′ N. lat., and between 9° and 22° E. long., and is surrounded by the Arctic Polar Sea, of which that portion which lies west of Spitzbergen is distinguished by the name of the Greenland Sea, because it extends to the eastern coasts of Greenland.

The group consists of three larger and numerous smaller islands which lie about the larger islands. The largest island is on the west, and extends from 76° 30' to 80° N. lat.; it is properly called Spitzbergen, and its most eastern part is called New Friesland. To the east of New Friesland lies North-east Land, which extends from 79° 10′ to 80° 10′ N. lat., and is divided from the larger island by the Henloopen or Waygatz Strait, which is about 70 miles long, and varies in breadth from 4 to 11 miles. East of the main body of Spitzbergen, and south of New Friesland, is Edges Island, which extends from 77° 15′ to 78° 15' N. lat., is separated from New Friesland by a strait called Walter Tymens fiord, or Alderman Freeman's inlet. This strait is somewhat more than 50 miles long, and less than 10 wide. Along the southern coast of Edges Island numerous small islands cover the sea to a distance of 15 miles from the shores, and this group goes by the name of the Thousand Islands. A considerable number of smaller islands are also dispersed over the sea which surrounds North-east Land on the nort and east, in Henloopen Strait, and round the north-western coast of Spitzbergen. In other places along the coast the smaller islands are not numerous, but at the distance of 12 or 15 miles from the western coast of Spitzbergen is Charles Island or Forland, which is about 40 miles long, but only a few miles wide.

Nothing is known of these islands except those parts which are contiguous to the sea, and even the coast is imperfectly laid down in our maps, with the exception of the western coast, which for more than two centuries has been annually visited by many whaling vessels, and thus has gradually become well known, and has been partially surveyed

On this supposition, says M. de Blainville, in conclusion, the normal disposition of Spirula would be to float constantly on the surface of the sea, like the Janthine [JANTHINA] and Physsophora [PHYSOGRADA, vol. xviii., p. 137], and equally by the means of an aëriferous float of calculated

In the early part of the memoir, M. de Blainville says of Dr. Buckland's theory: Pour accepter cette nouvelle hypothèse, il faut admettre les points suivants, que M. Kuckland considère, à ce qu'il paroft, comme prouvés: 1. La communication du péricarde avec le siphon. 2. L'existence du siphon membranenx creux et à découvert, dans les loges ou dans les intervalles des cloi

sons.

3. L'existence constante d'un liquide dans le péricarde. 4 La pesan teur spécifique de ce liquide, plus grande que celle de l'eau de mer. 5. La vacuité complete, si ce n'est d'air, des loges on chambres de la coquille. Or. de ces différentes theses, il n'y a peut être-that pent-être, like our if is a great peace-maker-que la dernière qui soit complètement hors de doute.'

We do not think that we shall be deemed presumptuous, if we add numbers 1 and 2; and we could say something of the others, but let them pass for the present.

other, the intervening valleys, being of moderate extent, are filled with glaciers, which in several places constitute the very shores of the sea, forming a high perpendicular wall of ice from 100 to 400 feet high. The inland valleys, in all seasons, present a smooth and continuous bed of snow, in some places divided by considerable rivulets, but ia others exhibiting an unbroken surface for many miles in extent.

The southern extremity of Spitzbergen is called Point Look-out, or South Cape: a low flat, about 40 square miles in surface, constitutes the termination of the coast. On the isthmus, which joins this flat tract to the main body rises a mountain-chain, which runs north, and soon attains a considerable elevation, as a large glacier or iceberg lies here along the sea-shore. North of 77° N. lat. is a wide bay, called Horn Sound, near the southern shores of which lies Mount Horn, or Hedge-hog Mount, which has several summits, chiefly in the form of spires, the highest of which is 4395

feet. Horn Sound has tolerable anchorage. A little to the northward of Horn Sound is a glacier of immense extent, occupying 11 miles of the sea-coast. The highest part of the precipitous front adjoining the sea is 400 feet, and it extends backward towards the summit of the mountain to about four times that elevation. Bell Sound, another wide bay, occurs between 77° 35′ and 77° 40′ N. lat., and within it are several anchoring-places. North of 78° is Ice Sound, where good anchorage is found at Green Harbour. That portion of Spitzbergen which is south of 78° 50′ N. lat. consists of groups of isolated mountains, partly disposed in chains, having conical, pyramidical, or ridged summits, sometimes round-backed, frequently terminating in points, and occasionally in acute peaks not unlike spires.

To the north of 78° 50' N. lat. are English Bay, King's Bay, and Cross Bay, in which there is good anchorage. Near the head of King's Bay there are three piles of rocks of a regular form, called the Three Crowns, which resemble the teocallis of the antient Mexicans. They rest on the top of a mountain, and each commences with a square table or horizontal stratum of rock, on the top of which is another of similar form and height, but of smaller area; this is continued by a third and fourth, and so on, each succeeding stratum being less than that immediately below it, until it forms a pyramid of steps, almost as regular as if it were worked by art. North of Cross Bay the mountains are more disposed in chains than farther south. The principal ridge lies nearly north and south, and the main valley extends from the head of Cross Bay to the northern coast, a distance of 40 or 50 miles. An inferior chain of hills, six or nine miles from the coast, runs parallel to the shore, and from this chain several lateral ridges project into the sea, where they terminate in mural precipices. Between those lateral ridges are the Seven Icebergs, each of which is, on an average, about a mile in length, and near 200 feet high near the sea. The higher mountains terminate near 79° 35′ N. lat., and the lower coast, which extends hence to the north, is indented by many small inlets, surrounded by numerous small islands of considerable height. In this part there are several very good harbours and anchorages, both in the inlets and between the islands, as Magdalena Bay, the excellent harbours of Smeeresberg, Fair Haven, Vogel Sang, the Norways, Love Bay, Heckla Cove, in the bay of Treurenburg, on Waygatz Strait, and others.

The centre of Charles Island, which lies opposite the western coast of Spitzbergen, is occupied by a mountainchain about 30 miles in length, rising on the west side from the sea, and on the east from a narrow strip of level ground only a few feet above the sea level. The central part of this chain is perhaps the highest land near the sea. It rises from the water's edge by a continual ascent, at an angle at first of about 30°, and increasing to 45° and more, until it terminates in five distinct summits, of which the highest is 4500 and the lowest 4000 feet above the sea-level.

Along the north shores of Spitzbergen and North-east Land the country is neither so elevated nor are the hills so sharp-pointed as on the west coast. Some of the smaller islands which occur along these shores, and considerable tracts of the mainland, are comparatively level. They also contain much more earth and clay, and the vegetation is rather more vigorous. Along the east coast of North-east Land there is a continuous line of glaciers extending to the shore. We have very little information respecting the eastern and southern coasts of Spitzbergen, as well as those of New Friesland and Edges Island.

Extending to within 10° of the pole, the climate of Spitzbergen is intensely cold. The mean temperature of the three warmest months on the western coast does not exceed 34.50°, and even at that season this part of the island is occasionally subject to a cold of three, four, and more degrees below the freezing-point. In the northern parts the longest day is four months; but from the 22nd of October to the 22nd of February the sun does not rise above the horizon. This long night however is not quite dark, for the sun, even during its greatest south declination, approaches within 13 of the horizon, and causes a faint twilight for about one-fourth part of every twenty-four hours. If we add to this the aurora borealis, which sometimes exhibits a brilliancy approaching to a blaze of fire, the stars, which shine with unusual brightness, and the moon, which in her north declination appears for 12 or 14 days together without setting, we may conceive that during the long night there is generally sufficient light to enable a person to go abroad.

The winter sets in at the end of September, or beginning of October, with winds from the north, north-north-west, or north-west, or with calms, hard frost, and snow. In the middle of October the frost is sometimes very intense, and it increases rapidly in November. But throughout the whole winter, when strong south winds occur, they are generally accompanied with mild weather, and sometimes with thaw. Storms in this season are so frequent that two-thirds of the weather may be said to be boisterous. The highest winds occur about the time of the equinoxes, and blow most frequently from the south. A great quantity of snow falls every winter, but it accumulates principally in the sheltered glens, lying on the level ground seldom more than five feet deep. Captain Parry however found that the climate of the northern coast is remarkably temperate in summer for the latitude, and very agreeable, but only so near the land, that of the adjacent sea being of a totally different character, owing to the almost continual fogs. In May and June the sea was almost entirely covered with large fields or floes of ice, but in August it was hardly possible to discover a single piece of ice, so great was the change which had been produced by the continual presence of the sun.

The number of species of plants which have been found in Spitzbergen hardly exceeds forty, but vegetation is very rapid. Most of the plants spring up, flower, and produce seed in the course of a month or six weeks. They are of a dwarf size, and the only plant which partakes of the nature of a tree is a Salix herbacea, which grows to the height of three or four inches. The islands do not produce vegetables suitable or sufficient for the nourishment of a single human being.

As only a small part of Spitzbergen has been visited, we know very little of its mineral productions. In some parts of King's Bay a very beautiful marble and coal of good quality are abundant.

The quadrupeds are- -polar foxes, polar bears, and reindeer. The adjacent sea abounds in many species of whales and some other large fish, and for more than two centuries a very advantageous fishery has been carried on. There are also many morses or walrusses, and abundance of seals. Sea-fowl are exceedingly numerous: some of the rocks along the western coast are literally covered with them.

Spitzbergen was discovered in 1596, by Barentz, Hemskerke, and Ryp, in their endeavour to effect a north-east passage to the Indies. It was named by them Spitzbergen (pointed mountains) from the numerous peaks observed on the coast. In 1607 it was visited by Henry Hudson, and four years afterwards the English began to resort to it for the whale fishery. Some sailors were left on these shores by accident on several occasions, and they passed the winter there: in some instances they died of the scurvy, but in other cases they survived and returned home. In 1743 four Russians were left there for six years, and thus the fact was ascertained that human beings could pass the winter in Spitzbergen without injury to their health. Sines that time the Russians have frequently visited these islands. They proceed from Archangel, Mezen, Onega, and Kola, in vessels of 60 to 160 tons, some of which are intended for the summer fishing and others for the winter. The former put to sea in the beginning of June, and return in September; the latter sail about a month later, winter in some of the harbours, and return home in August or September of the following year. They also kill a great number of morses, polar bears, and foxes, and bring home many skins of these animals.

(Scoreby's Account of the Arctic Regions; and Parry's Narrative of an Attempt to reach the North Pole in Boats.) SPIZAËTUS, M. Vieillot's name for a genus of FALCONIDE, placed by Mr. Swainson under the subfamily Buteonine or Buzzards.

Generic Characler.-Form aquiline, with the bill of a buzzard. Bill strong, high, curved from the base, with a prominent festoon. Orbits and lores covered with down and hairs. Wings short. Tarsi moderate, feathered. Inner toe, without the claw, shorter than the outer. Rasorial. (Sw., Mr. G. R. Gray arranges the genus under the subfamily Aquilinæ or Eagles.

SPIZELLA, the name given by the Prince of Canino to a genus of Fringillinæ or Finches.

SPLACHNUM, the name of a genus of cryptogamic plants belonging to the natural family of Mosses. The word is adopted from Dioscorides, who used both orλávov and Boúov to designate the families of lichens and mosses. It is known by its terminal fruit-stalk; single peristome with 8

double teeth; capsule with an evident apophysis, and mitriform, glabrous, furrowless calyptra. They are generally annual plants, and remarkable amongst their tribe for their size and beauty as well as singularity. Seven of the species are British. The most common in England is the Splachnum ampullaceum, purple gland-moss, which is found growing chiefly on rotten cow-dung. The receptacles are obtuse, inversely conical, of a greenish-purple colour, and three times as thick as the capsule.

S. sphæricum, green globular gland-moss, has a green globular receptacle, with ovato-lanceolate, pointed, entire leaves, and a capillary fruit-stalk. It is a native of alpine situations in the north of Europe and Scotland, and is generaily found on cow-dung. It occurs in green tufts, and has elegant slender wavy tawny fruit-stalks from one and a half to three or four inches high.

S. rubrum, red umbrella gland-moss, has an orbicular convex red receptacle, with partially toothed leaves. The fruit-stalks are six inches in length; the receptacle is very conspicuous, being half an inch wide, and having the form of an inverted cup, which is of a rich crimson colour and finely reticulated, making this moss one of the most remarkable and beautiful in the family. It is a native of Norway, Finland, Russia, and Siberia.

SPLEEN (EƊλýv, Lien, Splen). There are few parts of the human body on which more has been written than on the spleen, and none where the result has been more unsatisfactory. The purpose which it serves in the animal economy still remains entirely unknown; and the physiological part of this article must consist of a mere historical recapitulation of the various theories respecting its functions, which have successively been for a time adopted, and have then fallen into oblivion.

The spleen is an organ which is not found in any tribe below the class of fishes. Some animals have two, and this number has not unfrequently been found in man; for, as Haller says (Elem. Physiol., t. vi., p. 388), everything connected with this organ is uncertain and variable. Its form is generally somewhat oval, being smooth and convex on the exterior, where it is in apposition with the diaphragm, and irregularly concave on the opposite side, which is unequally divided into two parts by a transverse slit for the transmission of its vessels. (Quain, Elem. of Anat.) It is for the most part placed in the left hypochondriac region, between the diaphragm and the stomach, and beneath the cartilages of the ribs. (Quain.) It varies so much in size, that it is almost impossible to say what are its normal proportions. (Bichat, Anat. Descr.) It is much enlarged oy disease, as will be hereafter noticed; but in health, takig a general average, its greatest diameter may be said to measure about four inches, its breadth three, and its thickness from two to two and a half; its usual average weight is from eight to ten ounces. It is of a slight spongy consistence (ápaiòs xai σTоуyoεions, Hippocr. De Morb. Mulier, lib. i., tom. ii., p. 683, ed. Kühn), and is at all times easily torn; and in many cases it is found, soon after death, so soft as to be readily broken by a slight pressure, when it appears a grumous, dark, confused mass. Its colour is deeply red, with a tinge of blue, particularly round its margin. It has a peritoneal investment prolonged to it from the stomach, by which, as well as by vessels, it is connected with that organ; but it has also a smooth and fibrous tunic proper to itself, which is so firmly adherent to the serous investment above mentioned, that they cannot be separated except at its concave surface. (Quain.) No organ receives a greater number of blood-vessels in proportion to its size than the spleen; a fact noticed by all anatomists, and the more so because it secretes no fluid of any sort, at least none that has hitherto been discovered. (Bichat.) Almost all the blood that it receives is derived from the splenic artery (Halier, p. 400, 401): this is the largest branch of the coeliac axis, and near the spleen divides into several branches, some of which enter the fissure in that organ, and are distributed to its substance. These are called the rami splenici; they are five or six in number, and vary in length and size. (Quain.) They are the proper terminal branches of the artery, and by infinite ramifications form within the substance of the spleen a capillary system, which probably anastomoses in a direct manner with the capilaries of the veins (Bichat), as is proved by the facility with which injections pass from one to the other. The splenic vein is a vessel of very considerable size compared with the bulk of the organ; and it returns the blood not only from the spleen,

|

but also from the pancreas, duodenum, the greater part of the stomach and omentum, the left colon, and part of the rectum. It commences by five or six branches, which issue separately from the fissure of the spleen, but soon join to form a single vessel. Its direction is then transverse from left to right, embedded in the substance of the pancreas, in company with the splenic artery, beneath which it is placed. On reaching the front of the spine it joins the superior mesenteric vein nearly at a right angle, from the conflux of which proceeds the vena porte. (Quain) The nerves of the spleen accompany the splenic artery, and are derived from the solar plexus, forming an interlacement called the splenic plexus, previous to their entrance into it. (Ibid.) They are small compared with the size of the organ; and accordingly the spleen has very little sensation, a fact which was noticed as early as the time of Aretæus. (See De Caus. et Sign. Diuturn. Morb., lib. i., cap. 14, p. 111, ed. Kühn; Haller.) Its lymphatic vessels are very numerous; but as no appreciable product is elaborated by this apparatus, it has no excretory duct. (Quain.) The fibrous or proper coat of the spleen sends into its interior a multitude of cellular bands and fibres, which form by their intersections cells of various forms and sizes, and support the soft, pulpy, red tissue of the organ. In the red substance there are in many animals contained whitish round corpuscules, visible to the naked eye, which were first discovered by Malpighi, and of which the existence in the human spleen has been at one time admitted and at another denied. The corpuscules of the human spleen are described by Dupuytren and Assolant as greyish bodies, devoid of internal cavity, and measuring one-fifth of a line to one French line in diameter, and so soft as to take a liquid form when raised on the knife. Meckel describes them as roundish whitish bodies, one-sixth of a line to one line in diameter, most probably hollow, and at all events very soft and very vascular. In the human spleen the Malpighian corpuscules are distinguished with great difficulty. Müller mentions (Elem. of Physiol., by Baly, vol. i., p. 618) having seen them in a spleen which had been macerated. They were very firm, and much smaller than the greyish soft points sometimes seen in eut surfaces of the spleen, which have been described under the name of Malpighian corpuscules, but which are in reality very different from them.

Physiology. Of the functions of the spleen, as was before remarked, we still remain in perfect ignorance. The most antient opinion concerning its use in the animal economy is that which is found in the writings attributed to Hippocrates, and is connected with the famous doctrine of the four humours. The heart,' says the author of the fourth book De Morb. (tom. ii., p. 325, ed. Kühn), is the source of the blood (aipa), the head of the phlegm or pituita (péyua), the spleen of the water (dwp), and the liver of the bile (xoλ)'. This water was attracted by the spleen from the fluids received into the stomach (ibid., p. 333; De Morb. Mul., lib. i., tom. ii., p. 683), and thus the whole of this theory bore a striking resemblance to one of those that have been proposed in quite modern times. In another part of the Hippocratic collection (De Loc. in Hom, tom. ii., p. 130), it is said that those persons whose spleen is large have their body meagre (Conf. Gal., De Natur. Facult., lib. ii., cap. 9, tom. ii., pp. 132, 133), an idea which is found also in Plato (Timaus, cap. 47, ed. Stallb.), and which gave rise to the well-known comparison of Trajan, who said that the imperial treasury was like the spleen, because when that was rich the people were impoverished. (Aurel. Vict, Epit., cap. 42, sec. 21.) Aristotle (De Part. Anim., lib. iii., cap. 7, p. 86), calls the spleen a spurious (vó@ov) liver, to which it is a sort of equipoise (avtiLvyor, ibid., cap. 4, p. 76), says that it is not an organ necessary for all animals (ibid.), and that it assists the liver in performing the functions of digestion (ibid., p. 87, ed. Tauchn.) In another obscure passage (ibid., p. 88), he says that the spleen attracts from the stomach (ccia) the superfluous and excrementitious humours (ixuádag ràç teplotác), and concocts them,' by which he is supposed by Casp. Hofmann (De Liene, cap. 5) to mean the chyle. It is surprising that so eminent an anatomist as Erasistratus, while confessing that nature does nothing without a reason (Gal., De Usu Part., lib. iv., cap. 15, tom. iii., p. 315; id., Comment, in Hippocr. De Alim.,' sec. 14, tom. xv., p. 308), should nevertheless consider the spleen to be a useless organ (Gal., ibid.; id., De Atra Bile, cap. 7, tom. v., p. 131; id, De Natur. Facult., lib. ii., cap. 4, 9, tom. ii., pp. 91, 131, sq.),