87$ 



SPIRAL VESSELS. 



Sl'LEEX. 



mtin*l relation which may be expressed by figures, and which resulbi 

 from the combination of the element* of which they arc composed. 

 All the spire* depend upon the position of a fundamental series, from 

 which the others are deviations. The nature of thi* aeries is expressed 

 by a fraction, of which the numerator expresses the number of tunis 

 which make up one spire, whiUt the denominator expresses the 

 number of leave*, scale*, Ac., upon the spire. So that suppose we 

 mark the seat of one leaf at the bottom 0, and go on following the 

 leaves, we shall come at one directly over the first, and this completes 

 the spire; if this leaf occurs after ten turns of the spiral, and there 

 should be eighteen leave* upon the spire, the expression for this series 

 would be (J. By applying this rule very different figures may be 

 obtained for various plants. The following ore results obtained by 

 Braun:- 



A is the expression for the leave* of Woad, J'lanlayo lanccolata, 

 and the bracts of IHgitalii laaala. JJ in Semptnivum arboreum, and 

 the bracts of Plantago media. J is a common form ; it exists in the 

 bay-tree, the holly, and Aconite. ] is the most common, representing 

 the Q*i*f**x. It is seen in Alnereum, Laptana com.mu.nii, the potato, 

 Ac. ) is seen in the spikes of all grasses, in Atraum, the lime tree, 

 the vetch, and pea. 



No application of this doctrine has at present been made, and these 

 researches are only in their infancy. It seems in some genera to be a 

 mode of distinguishing specie*. Thus the expressions for the following 

 species of Pin>u are P. pinatttr, Jl ; P. sytrcstrii, i; ; P. Cembra, ; 

 P. lariz, ft ; P. microcarpa, }. 



(Gothe, Ueber die Spiral-Tcndeni der Vegetation ; Heyen, Pfanirn- 

 Pkftioloyie, band iii. ; Lindley, Introdvcti-m to Botany ; Heuslow, 

 Botany, in Cabinet Cyc. ; Virey, Philotop/iie de Cllittoirc NatureUe.) 



SPIRAL VESSELS. [TISSUES, VEGETABLE.] 



SPIRALIS. [HXAUHDJa,] 



SPIRATELLA. 



SPIRICELLA. 



SPI'RIFER (Sowerby), a group of Fossil Brachiopoda. 



SPIRIT-DUCK. [DUCKS.] 



SPIRO'RBIS. [TrmcouDX.] 



SPI'RULA. [Sl'IRULlDJR.] 



.SPIUT'LID-K, Professor Owen's name for a family of Polytha- 

 lamous Decapodous Dibranchiate Cephalopoda. 



The family is thus characterised : Shell partly internal ; cylin- 

 drical, multilocular, discoid ; the whorls separated ; septa transverse, 

 concave next the outlet, and with regular intervals. Siphon marginal 

 and internal, uninterrupted. Animal having an oblong body with 

 minute terminal fins, the mantle supported by a cervical and two 

 ventral ridges and grooves. Anus with six rows of very minute cups ; 

 tentacles elongated. Funnel valved. 



The character of the family is that of the genus Spirula, of which 

 it is at present composed. 



Professor Owen make* three species of the ffauliliut Spirula of 

 Linustus. These are Spirula Peronii, S. Auitrala, and S. rtticulata. 

 The shell of one or other of these species is not unfrequently found 

 on the British coast, and instance* an recorded of its having been 

 found on the coast* of Ireland, Cornwall, and Devon. The animal 

 has been very seldom taken whole, and the portions that have been 

 found led to much discussion, till one was obtained perfect by Mr. 

 Percy Earle on the coast of New Zealand. The shells are found in 

 great abundance on the coast* of New Zealand. They abound also on 

 the Atlantic coasts. 



SPI'SULA (J. E. Gray), a genus of Conchifera founded on Mactra 

 frayilit ami similar specie*. 



HPIZAETirS (Vieillot), a genus of Birds. [FALCONID.K.] 



8PIZELLA (Bonaparte), a genus of PrimjiUimr. 



8PLACHNL' M, the name of a genus of Cryptogamic Plant* belong- 

 ing to the natural order of Moeses. The word is adopted from 

 Dioscorides, who used both SrAtixror and Bpiwx to designate the 

 families of Lichens and Mowe*. It is known by it* terminal fruit- 

 stalk ; single peristome with eight double teeth; capsule with an 

 evident apophysia, and mitriform glabrous furrowless oalyptra. They 

 are generally annual plants, and remarkable amongst their tribe for 

 their sizu and beauty a* well as singularity. Seven of the species 

 are BritUh. The most common in England is the .*>'. amjiullaceum, 

 Purple Gland-Moss, which i* found growing cbiefly on rotton cow- 

 dung. The receptacles an obtuse, inversely conical, of a greenish- 

 purple colour, and three time* as thick as the capsule. 



S. rpMrtricum, Green Globular Gland-Mow, has a green globular 

 receptacle, with ovato-lanceolate, pointed, entire leaves, and a capillary 

 fruit-sulk. It is a native of alpine situations in tho north of Europe 

 and Scotland, and i* generally found on cow-dung. It occurs in green 

 tufte, and has elegant .lender wavy tawny fruitHrtalks from one and a 

 half to three or four inches high. 



S. nbrum. Red Umbrella < Hand-Mow, has an orbicular convex red 

 receptacle, with partially toothed leaves. The fruit-stalk* are *ix 

 inches in length ; the receptacle is very conspicuous, being half an 

 inch wide, and having the form of an inverted cup, which i* of a 

 rich crimson colour and finely reticulated, making this mom one of 

 the most remarkable and beautiful in the family. It is a native of 

 Norway, Finland, Russia, and Siberia. 



SPLEEN (*A*r, Lien, Spltt). There are few part* of the human 



body on which more has been written ttian on the Spleen, and none 

 where the result ha* been more unsatisfactory. The purpose which 

 it serves in the animal economy is still only imperfectly known, and 

 the record of the theories which have been entertained of it* use* is a 

 moat uninstructive page in human physiology. 



The Spleen is an organ which is not found in any tribe of animals 

 below the class of fishes. Some animaU have two, and this number 

 has not unfrequently been found in man ; for, a* Haller says (' Elem. 

 Physiol.,' t. vi. p. 3SS), everything connected with this organ is un- 

 certain and variable. Its form is generally somewhat oval, being 

 smooth and convex on tho exterior, where it is in apposition with tho 

 diaphragm, and irregularly concave on the opposite side, which is 

 unequally divided into two parts by a transverse slit fur the trans- 

 mission of it* vessels. (Quain, ' Elem. of Anat.') It is for tho most 

 part placed in the left hypochondriac region, between the diaphragm 

 and the stomach, and beneath the cartilages of the ribs. (Quaiu.) 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 

 by disease, as will be hereafter noticed ; but in health, taking a general 

 average, its greatest diameter may be said to measure about four 

 inches, iU breadth three inches, and its thickness from two to two 

 and a half inches ; its usual average weight is from eight to ten ounce*. 

 It is of a slight spongy consistence (apcu&r Kal aroyyoiiSiit, Uippocr. 

 'De Morb. Mulier.' lib. i. torn, it p. 633, ed. Kiihn), 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 invest- 

 ment 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 invest- 

 ment above-mentioned, that they cannot be separated except at it* 

 concave surface. (Quoin.) No organ receives a greater number of 

 bloodvessels 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. (LSicbaU) 

 Almost all the blood that it receives is derived from the Splenic 

 Artery (Haller, p. 400, 401) ; this is the largest branch of the cooliac 

 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 Kami Splenici ; they are five or six in number, 

 and vary in length and size. (Quain.) They ore the proper terminal 

 branches of the artery, and by infinite ramifications' form within tho 

 substance of the Spleen a capillary system, which probably anasto- 

 moses in a direct manner with the capillaries 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 com- 

 pared 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 traversed 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 portro. (Quain.) The nerves of the ."- 

 accompany the Spleuic Artery, and are derived from the solar plexus 

 forming on interlacement called the Splenic Plexus, previous to tluir 

 entrance into it. (Ibid.) They are small compared with the sizu of 

 the organ ; and accordingly the Spleen has very little sensation, a fact 

 which was noticed as early as the time of Arcticus. (' De Caus. et 

 Sign. Diuturn. Morb.,' lib. i. cap. 14, p. Ill, ed. Kuhu ; Haller.) Its 

 lymphatic vesseU are very numerous ; but as no appreciable product is 

 elaborated by this apparatus, it has no excretory duct (Quoin.) The 

 fibrous or proper coat of the Spleen sends into its interior a multitude 

 of cellular bands and fibres, which form by their iuternectious 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 corpuscles, visible to the naked eye, which were first 

 discovered by Malpighi, and of which the existence iu the human 

 Spleen ha* been at one time admitted and at another denied. The 

 corpuscles of the human Spleen are described by Dupuytreu and 

 Aasolant as grayish bodies, devoid of internal cavity, and measuring 

 one-fifth of a line to one French line in diameter, and so often as to 

 toko 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 proboly hollow, and at all events very soft and very vascular. 

 In the human Spleen the Malpighian corpuscules are distinguished 

 with great difficulty. They vary from one-third to one-sixth of a 

 line, and much smaller corpuscles are seen, which are probably com- 

 mencing stages of the larger ones. Each of the corpuscles is formed 

 of a fibrous envelojte, which it appears to derive from the coat of the 

 artery to which it is attached, aud is often surrounded by minute 

 capillaries. When crushed the corpuscles are found to consist of very 

 minute indented cells and free nuclei. Dr. Sanders describes also a 

 layer of nucleated spherical cells, which are placed beneath tho 

 corpuscle. Each corpuscle, according to Dr. Sanders, is traversed by 



