SEROUS MEMBRANES 



SERPENTS 



323 



tunica vaginalis testis, and the synovial fluid ; (2) 

 the tears and the fluids existing in the eyeball, the 

 amniotic fluid, and transudations into the tissue of 

 organs; (3) morbid or excessive transudations, 

 such as dropsical fluids, the fluids occurring in 

 hydatids, and in blebs and vesicles on the skin, 

 and transudations from the blood in the intestinal 

 capillaries, as in cases of intestinal catarrh, eholear, 

 or dysentery. All these fluids bear a close resem- 

 blance to one another, both in their physical and 

 chemical characters. In so far as relates to their 

 physical characters they are usually clear and trans- 

 parent, colourless or slightly yellow, of a slight 

 saline, mawkish taste, and exhibiting an alkaline 

 reaction with test-paper. They possess no special 

 formal or histological elements, but on a microscopic 

 examination blood-corpuscles, cells of various kinds, 

 molecular granules, and epithelium may occasion- 

 ally be observed in them. The ordinary chemical 

 constituents of these fluids are water, librin ( occa- 

 sionally), albumen, the fats, animal soaps, clioles- 

 terin, extractive matters, urea (occasionally), the 

 same inorganic salts which are found in the serum 

 of the blood, and the same gases as occur in the 

 blood. 



Serous Membranes. There are six of these 

 membranes in the human Imdy, two being median 

 and single, while two are double and lateral. They 

 are the pericardium and the peritoneum, with the 

 two pleura and tunicas vaginales testis. They are 

 all closed sacs, with one exception ; and each 

 sac or continuous membrane consists of two por- 

 tions a parietal one, which lines the walls of the 

 cavity, and a visceral or reflected one, which forms 

 an almost complete coating or investment for the 

 viscera contained in the cavity. The interior of 

 the sac contains a small quantity of fluid, usually 

 merely enough to moisten the contiguous surfaces 

 and thereby enable them to glide easily upon each 

 other. With regard to their structure, it is suffi- 

 cient to state that they consist essentially of ( 1 ) 

 endotheliurn ; (2) basement membrane; (3) a 

 stratum of areolar or cellular tissue, which con- 

 stitutes the chief thickness of the membrane, and 

 in the constituent on which its physical properties 

 are mainly dependent. This layer is more liable 

 to variation than the others, and one of the most 

 common alterations is an augmentation of the 

 yellow fibrous element, by which an increased 

 elasticity is given to the membrane, which is thus 

 better adapted for distention, and for a subsequent 

 return to its original bulk. The situations in which 

 this augmentation is found are, as Dr Brinton 

 (Cyclopaedia of Anatomy and Physiology, vol. iv. p. 

 524) has pointed out, in exact conformity with this 

 view : in the peritoneum, which lines the anterior 

 abdominal wall and covers the bladder, it attains 

 its maximum ; in the detached folds of the nifM'n- 

 tery, in the costal pleurae, and in the suspensory 

 ligament of the liver it is still very prominent ; 

 while on the posterior wall of the belly, and in 

 serous membranes covering the heart, liver, &c. it 

 is almost absent. For some of the principal serous 

 membranes, see the articles PERICARDIUM, PERI- 

 TOXEUM, PLEURISY, and RESPIRATION (Vol. VIII. 

 p. MO). Synovia] membranes (q.v.) present many 

 |K>ints of similarity to serous membranes. 



Serpent, a bass musical wind-instrument 

 entirely obsolete except in a few continental 

 Imrches. It is said to have been invented by a 

 Kn-iich priest at Anxerre in 1590. It consists of a 

 r<;d tule 8 feet long, built of wood and covered 

 with leather, and twisted about like a serpent, 

 whence the name. It is sounded through a cupped 

 mouthpiece like that of the bass Trombone (q.v.). 

 It had originally six holes for three fingers of each 

 hand, but in its later years had keys added. The 



Serpent. 



form of its bore and the material of which it is 

 made give it a tender and soft tone which is very 

 effective in certain kinds of 

 music, but its difficulties and 

 the uncertainty of its intona- 

 tion have led to its disuse. 



Serpentine, a mineral 

 composed of silica and mag- 

 nesia in almost equal propor- 

 tions, with about 13-15 per 

 cent, of water, and a little 

 protoxide of iron. Serpentine 

 occurs generally massive ; never 

 in crystals, save as pseudo- 

 morphs ; colour some shade of 

 green, also red and brownish 

 yellow ; has a smooth but 

 sometimes greasy feel ; is soft 

 enough to be scratched with 

 calcite. Precious Serpentine, 

 or Noble Serpentine, is of a 

 rich, dark-green colour, hard 

 enough to receive a good polish, 

 translucent, and sometimes contains imbedded gar- 

 nets, which form red spots, and add much to its 

 beauty. It is a rare mineral. It occurs at Baireuth 

 in (Germany, in Corsica, at Portsoy in Banffshire, in 

 the Shetland Islands, &c. It is generally found 

 along with foliated limestone associated with schis- 

 tose rocks. The ancient Itomans used it for pillars 

 and for many ornamental purposes; and vases, 

 boxes, &c. are still made of it, and much prized. 

 The ancients ascribed to it imaginary medicinal 

 virtues. Marmolite is a scaly, foliated serpentine ; 

 Chrysotile is a delicately fibrous variety, with a 

 silky lustre, often met with as veins in ordinary 

 serpentine. Common Serpentine is a rock rather 

 than a mineral. It often occurs in winding irregular 

 veins ; hence the name serpentine. It is generally 

 green or red, the colour being sometimes uniform, 

 at other times innttled, spotted, streaked, veined, or 

 clouded. It occurs not only in veins, but forming 

 irregular sheets and masses, and is usually asso- 

 ciated with crystalline schists and granitoid erup- 

 tive rocks. The mineral serpentine is always a 

 product of the chemical alteration of other minerals ; 

 and there is reason to believe that most of the 

 masses of serpentine are highly altered igneous 

 rooks which were rich in olivine or peridote. Many 

 periilotites are proved to have been altered into 

 serpentine. Concerning the origin of some of the 

 serpentines associated with the crystalline schists 

 there is still much uncertainty. 



Serpents (I-at. serpere, 'to creep'), the more 

 formal and old-fashioned term for all members of 

 the genus Ophidia, more popularly known as Snakes 

 (q.v. ), under which heading the general characters 

 and classification of the Ophidians are treated, as 

 also snake-charming. 



SERPENT-WORSHIP is one of the most ancient 

 and wide-spread forms of primitive religion, and 

 still exists amongst many savage peoples. The 

 characteristic change of skin is easily associated 

 with notions of resurrection and immortality ; but 

 it does not appear that the familiar notion of the 

 serpent as a personification of evil is anything like 

 universally spread, although we do find it early 

 in the Apophis-serpent of the Egyptian Hades, 

 represented on mummy-cases, as well as in the 

 wicked Aji Dahaka of the Zoroastrians, which 

 bears so close a relation to the subtle Serpent 

 of Eden. The worship of Moses" brazen serpent 

 in the days of Hezekiah (2 Kings, xviii. 4) shows 

 that the idea was familiar to the Semitic mind. 

 Serpent-worship appears prominently in early 

 Indian Buddhism ; we see traces of it in the great 

 serpent which defended the citadel of Athens, fed 



