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WOL. IX.
Douay Bible [Bible]
Double Base, 104
Double Stars [Stars, Double]
Doubloon [Money]
Doubs (river), 104
Doubs (department), 105
Douche [Bathing]
Doucker §.
Douglas Family, 106
Douglas, Gawin, 108
Douglas [Man, Isle of]
Dour [Hainault]
Doura, or Durra [Sorghum vul-

gare]
Douro, 108
Douw, Gerard, 108
Dove so.
Dovedale [Derbyshire]
Dover, 108
Dovetail, 109
Dovrafield [Norway]
Dower, 109
Dowletabad, 109
Down o 110
Down (county), 110
Down §. 115
Downing College, Cambridge,
116

Downpatrick, 116
Downs, or Dunes, 117
Downton [Wiltshire]
Doxálogy, 117
Dracaena, 117
Drachm, or Dram, 118
Drachma, l 18
Dracína, 118
Draco, 118
Draco (constellation), 118
Draconin, 118
Dragomans, 119
Dragon, 119
Dragon's Blood [Calamus]
Dragoon [Cavalryl
Draguignan, 119
Drain [Sewer]
Draining, 119
Drake, Sir Francis, 122
Drakenborch, 124
Drama, Attic, 124
Dramatic Art and Literature,
125
Drammen, 136
Drastics [Cathartics)
Drave, 136
Drawback, 136
Drawbridge, 137
Drawing, 137
Drayton, 1.38
Dreams, 139
Drenthe, 146
Dresden, 146
Dreux, 148
Driffield [Yorkshire]
Drill, 148
Drill Husbandry [Drilling]
Drilling, 148
o [Canella Alba; Win-
tera

Drin, or Drino | Albanial

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E occupies the fifth place in the Hebrew alphabet and those derived from it. The vowels, when arranged according to their physical affinity, would lie in the series i, e, a, o, u [ALPHABET], and accordingly the vowel e is frequently interchanged with its neighbours i and a. It is occasionally convertible with o and u. 1. E is interchanged with i. Thus in Latin the old datives heri, mani, ruri, musai, afterwards took the forms here, mane, rure, musae; and the words magis, videris, tristis, when they appeared without an s, were written mage, videre, triste. The same interchange appears in the declension of the adjective is, ea, id, and the conjugation of the verbs eo and queo. 2. E in Latin often corresponds to oi in French. Thus many Latin infinitives in ere reappear in French with the termination oir, as habere, debere; avoir, derotr. The Latin past imperfect has the suffix eba, which passed through the forms eva and ea to oie and oi. Thus from habebam were deduced aveva, avea, avoie, and lastly avois. This final s does not appear in the oldest forms of the French language. Other instances of the change of o into oi may be seen in the Latin adjectives and other words in ensis or esrs, which in French have the suffix ois, as Vienmensis, Piennois ; mensis, mois. * E. Latin into ie French, as mel, bene, ped; miel, bien, zea. p 4. E into a. This is well marked in the dialects of the Greek copin, Ionic; copia, Doric, &c. Hence the Latins have often an a where the common dialect of the Greek had e, as anxavn, TXmYn; Lat. machina, plaga. Both forms often coexist in Latin, as tristitia and tristitie. The a is often changed into e in Latin, if a prefix is added, particularly if two consonants follow the vowel, as factus, confectus; pars, ea pers ; castus, incestus; ars, iners. 5. E into o, Especially in Greek, as Āeyw, Aoyoc ; wspaw, voucc. The Latin language prefers the o, as tuto, vomo; are tra, coquo; vioc, novus. This change is particularly common in words beginning with a w, or with what was pronounced as a w, the Latin v. Thus rester, velim, verto, veto, were once written voster, volim, vorto, voto. Even in our own language worm (vermis, Lat.), and work (spyov, Gr.), are now pronounced as if written with an e. The Greek even interchanges a long o with a long e, as trarmp, drarap, eitrarwp. 6. & Greek is changed into u in Latin before an l, as Xurexoc, Siculus. E (in music), the third note or degree of the diatonic scale, answering to the mi of the Italians and French, EADMER, or EDMER, the friend and historian of Archbishop Anselm, lived in the twelfth century, but we have no information respecting his parents, or the particular time and place of his nativity. He received a learned education, was a monk of Canterbury, and became the bosom friend and inseparable companion of two archbishops of that see, St. Anselm and his successor Ralph. To the former of these he was appointed spiritual director by the ope. In 1120, by the desire of Alexander I. of Scotland, e was elected bishop of St. Andrews: but on the day of his election a dispute arose between the king and him respecting his consecration. Eadmer wished to be consecrated by the archbishop of Canterbury, who, he contended, was the primate of all Britain; while Alexander contended that the see of Canterbury had no pre-eminence over that of St. Andrews. Eadmer finally abandoned his bishopric and returned to England, where he was kindly received by the archbishop and clergy of Canterbury, who yet thought him too precipitate in leaving his bishopric. Eadmer at last wrote a long and submissive letter to the king of Scotland, but without producing the desired effect. Wharton fixes his death in 1124, the very year in which the bishopric of St. Andrews was filled up. Eadmer is now best known for his history of the affairs of England in his own time, from 1066 to 1122, in which he has inserted many original papers, and preserved many facts which are no where else to be found. His style is regular and good, and his work more free from legendary tares than is usual with the works of his time. The best edition is that by Selden, intitled

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‘Eadmeri Monachi Cantuartensis Historia, Novorum, sive sui Saeculi, Libri Sex,’ fol., London, 1623. His life of St. Anselm was first printed in 12mo, at Antwerp, in 1551, under the title of “Fratris Edmeri Angli de Vita D. Anselmi Archiepiscopi Cantuariensis, Libri duo.” Several others of his works, with the ‘Historia Novorum,’ were edited by the congregation of St. Maur at the end of Father Gerberon's editions of the works of St. Anselm, fol., Par, 1675 and 1721. His Lives of St. Wilfrid, St. Oswald, St. Dunstan, &c., with that of St. Anselm, were inserted by Wharton in his Anglia Sacra. (Tanner, Bibl. Brut. Hib. Praef. ad era S. Anselmi ut supr. ; Chalmers's Biogr. Dict.) EAGLE. [FAlco NID.E.] EAGLE (constellation). [AQUILA.] EAGLE (coin). [Money.] EAGLE, Roman Standard. The eagle, as a symbol of empire, is often seen on antient coins and medals, and on none more frequently than on those of the Ptolemies of Egypt and the Seleucidae of Syria. . As an ensign or standard, borne upon a spear, it was used by the Persians in the time of the younger Cyrus. (Xenoph. Anab. i. 10.) Pliny (Hist. Nat. li. x. c. 4, edit. Hardouin, tom. i. p. 549) says that, till the time of C. Marius, the Romans used five different animals for standards—the wolf, the minotaur, the horse, the boar, and the eagle—but that in Marius's second consulate they adopted the eagle as the sole ensign for their legions. The eagle used by the Romans as a standard was of gold or silver; the latter metal, we are told by Pliny, was most frequently used, as the more glittering, and of course more readily seen. It was borne, like the ño, eagle, on the summit of a spear, and was of the size of a pigeon, with its wings displayed. It sometimes rested upon a cross bar on the top of the spear, and sometimes upon shields piled up. On the reverses of some of the coins of Augustus and Galba, in second brass, the legionary eagle is represented holding the thunderbolt in its talons. The small size of the eagle often contributed to its concealment, when the legion to which it belonged was defeated. The name of the legion was usually engraved upon it. Tacitus, in his Annals l. i. 60. relates the finding of the eagle of the nineteenth legion by Germanicus, which had been lost in the massacre of Varus. Cicero (Catilin. i. c. 24) says that Catiline had a silver eagle in his house as his tutelar divinity, which was also his standard in war. A Roman eagle in steel, found at Silchester, presumed to have been a legionary eagle, was exhibited to the Society of Antiquaries in 1788 by the then bishop of Carlisle. The reader will see a great deal of learning displayed upon this and the standard of the cohorts in M. Le Beau's ‘Quatorzième Mémoire sur la Legion Romaine; Des Enseignes. Mem. de l'Académie des Inscript. tom. xxxv. 4to. Par. 1770, pp. 277-308. EAGLE-WOOD, one of those substances of which the name, from similarity of sound in a foreign language, has been converted into another having no reference to its original signification. It is a highly fragrant wood, much esteemed by Asiatics for burning as incense, and known in Europe by its present designation ever since the Portuguese visited and imported the substance direct from the Malayan islands and the kingdom of Siam, where it has always been abundant, and long established as an article of commerce. The Malayan name is agila, whence the wood was called pao-d'agila by the Portuguese, and has since been converted into pao-d'aguila, and pao-d'aquila, bois-d'aigle, eagle-wood, and agel-hout. From the Malayan agila has probably been derived the Sanscrit agara, whence we have the Hindu aggur, if not from the more familiar appellation of garoo, by which eaglewood is also known in the Malayan Archipelago. In Persian works on Materia Medica in use in India, we learn from Dr. Royle (Illustr. of Himal. Bot., &c.) that several kinds of fragrant wood are described under the Arabic name aod (haud and ud of Garcias), and that he himself obtained three kinds in the bazaars of India, called aod-i-hindee, aod-i-chinee, and aod-i-kimaree (evidensy the al-cemericum of Arabian authors), and that with the above * a Greek 2

synonyme, agallochee, is also given, and more especially applied to aodi-kimaree, which is also called aod-i-bukhoor, incense-wood. As agallochee is no doubt a corruption of the agallochum of Dioscorides, described by him as a frag; rant wood from India and Arabia, it is interesting to find that the translators from the Greek into the Arabic of the school of Bagdad settled these synonyms at a time when they must have been well acquainted, from their profession and position, with the substances to which both the Greek and Arabic names were applied. Serapion and Avicenna describe several kinds of this fragrant wood, and the latter under both agalugen or aghaloojee, and aod, which in the Latin version is translated Xyloaloe, a name that was applied by the later Greek medical writers to agallochum, whence we have lignum aloes, lign-aloe, and aloes-wood, the origin of which it is difficult, if not impossible, to ascertain, unless we suppose it to be a corruption of agila; for the bitter, scentless, spongy-textured stems of the genus aloe could not afford any substitute for this fragrant wood, or be thought to yield it, at least by the Arabs, who were well acquainted with, and accurately describe aloes, and the place, Socotra, where the best kind is found. Though Dioscorides notices only one, which some supposed to be the Tarum of Pliny, several kinds of agallochum are described by Serapion and Avicenna, which, as it is not possible at present to identify, it is unnecessary to notice, and therefore we shall refer only to the three kinds which have been traced to the trees yielding them, by naturalists who have visited the countries where these are indigenous. An Aguila brava (wild) is mentioned by Garcias as produced near Cape Comorin, in the southern part of the Indian peninsula, and in the island of Ceylon; but the tree yielding this wood has not been ascertained. ... Rumphius (Herb. Amb. ii. p.40), describes two kinds of agallochum spurium, found in §. and Sumatra, one of which he calls Garo Tojampaca, which is described as having leaves and flowers resembling those of the celebrated champa, Michelia champaca, and may be a species of the same genus. A third kind of spurious agallochum, differing much from the others as well as from the genuine, he describes in another part of his work, ii. p. 240, as the produce of his Arbor earcaecans, so called from the acridity of its juice blinding people, and which is the Ercarcaria agallocha of Linnaeus. Considering that Rumphius, in originally describing this tree, has said “Lignum hoc tantam cum agallocha similitudinem,’ and as affording a substitute for that substance, it is not surprising that it should be frequently quoted as the tree which yields the genuine agallochum, or aloes-wood. Fée (Hist. Nat. Pharm.) states that he had seen a genuine specimen of the wood of this tree, and that its fragrance cannot be compared with the agallochum of Loureiro. Dr. Roxburgh mentions that the wood-cutters of the Delta of the Ganges, though well acquainted with the highly acrid and very dangerous milky juice of this tree (there called geria), do not mention agallochum of any kind being found in this tree. Of the two kinds of agallochum which are most valued, and both considered genuine, one is distinguished by the name of Calambac, and the other as the Garo of Malacca. The first, called calambac, and agallochum primarium by Rumphius, appears, as far as hitherto known, to be a native of Cochin China only, growing on the mountains of that country in about 13° of N. lat., near the great river Lavum, which may be the Meikeng flowing between Cochin China and is Laos. This tree was named Aloerybum agallochum by Loureiro, Fl. Cochin Chinensis, p. 327, and placed by him in Decandria Monogynia, and described as a lofty tree with erect stem and branches, long lanceolate shining leaves, terminal bunches of flowers, with a woody, falcate, one-seeded pod for its fruit, whence it is referred by De Candolle to the natural family of Leguminosae. Loureiro states that the wood of this tree is white and inodorous, and that its fragrance is the result of disease, when the oily portions thicken into resin in the central parts of the tree, and that no part of the tree is milky or poisonous, but that paper is made from its bark in Cochin China, as in Japan from that of the mulberry. The next kind of agallochum is that commonly called garos, and to which the name of eagle-wood is more frequently applied, and which has long been an article of export from W. and the kingdom of Siam. Specimens of the tree which yield this were first obtained by M. Sonnerat in his second voyage to India, from which probably have been given the figure and description by Lamarck.

(Enc. Méth., i., p. 49, Illustr. t. 376.) The plant he named Aquilaria Malaccensis. This, the Garo de Malacca, was introduced by Dr. Roxburgh into the Botanic Garden of Calcutta, and was not to be distinguished from specimens of a tree called ugoon, which is a native of the mountainous tracts east and south-east from Silhet, between 24° and 25° of N. lat., which flowers in April, and ripens its seed in August, and which he says there can be little or no doubt furnishes the real Calambac or Agallochum of the antients; adding, that there seems more reason to think that it was carried to China from our eastern frontier, than to suppose it Awas carried from Cochin China, or any other country in the vicinity of China, where it has always been in great demand. Small quantities are sometimes imported into Cal. cutta by sea, from the eastward; but such is always deemed inferior to that of Silhet. (Fl. Ind. ii. p. 423.) As the Malacca plant had not flowered, Dr. Roxburgh was unable to decide that they were positively the same with those from Silhet, and therefore named these Aquilaria agallocha, as another species of the same genus. By this name it has been figured in Royle's Illustr. i. 36, f. 1, from a drawing by Dr. Hamilton of a plant which he called Agallochum officinarum, and which he found near Goalpara, on the eastern frontier of Bengal. This drawing is illustrated with dissections by Dr. Lindley. To the above-quoted work, and the latter's ‘Natural System of Botany,’ we refer for the botanical details and the characters of the family of Aquilariaceae, to which this genus gives its name...The fragrant nature of genuine agila or eagle wood is well known, and that it has from very early periods been employed both by the natives of India and of China as incense. Mr. Finlayson, in his visit to Siam, says, that the consumption of this highly odoriferous wood is very considerable in Siam, but that the atest part is exported to China. In the latter, it is used in a very economical manner; the wood being reduced to a fine powder and mixed with a gummy substance is laid over a small slip of wood, about the size of bull-rush, so as to form a pretty thick coating. This is lighted, and gives out a feeble but grateful perfume. French authors inform us that the eagle-wood was burned as a perfume by Napoleon in the imperial palace. We cannot conclude this subject without inquiring whe. ther the substances of which we have been treating are the lign-aloes of Scripture, ahaloth, masc. ahel, whose plural is ahalim. It would be impossible to do justice to the subject in a small compass, or without referring to the numerous dissertations which have been written on it; but it may be observed, that these might have been much shortened, if the authors had been naturalists, or intimately acquainted with the natural history and usages of eastern countries; such information would at least have prevented any species of aloe being, considered or figured as the far-famed and fragrant lign-aloe from a mere similarity in sound. In the present instance, the difficulty is increased by the supposed necessity of reconciling the different passages in which lign-aloes are mentioned, as in Numbers, xxiv. 6, where it is mentioned as a tree planted; but in the three other passages, Pror. vii. 17, Psalms xiv. 9, and Canticles, iv. 14, it is enumerated with the most fragrant products of the East, as cinnamon, cassia, calamus, camphor, frankincense, myrrh, spikenard, and saffron. Here we may observe, that a substance which was indigenous in a country was not likely to have been an article also of commerce from a far country in those early times; and that therefore, as it is disputed whether the word shall be translated tents or lign-aloes, the word may perhaps be used in a poetical sense, as it is thought to be by some commentators. In the three passages, it may be noted, that, except sandal-wood, there is no other substance which could be so well enumerated with those with which it is found in connexion as the agila wood of the East, whether we consider its high price, delicate perfume, or the long time in which it has been held in high estimation, while the similarity of its name is at the same time remarkable. EAGRE. [Bore.] EAR. Many animals unquestionably enjoy the faculty of hearing to a limited extent, which are found, upon examination, to be unprovided with organs exclusively approriated to the concentration and transmission of sound. In act, the sense of hearing is, strictly speaking, only a refinement of the sense of touch. The impressions with which it is conversant arise wholly [Acoustics] from peculiar

undulations of the particles of ordinary matter, propagated in obedience to its ordinary laws through the medium in which the animal lives, and impinging more or less immediately upon a sensitive part; they have no necessary dependence, like those of sight, upon the agency of the more subtle flaids; nor have they any connexion, like those of smell and taste, with what may be called the chemical properties of matter. If to these considerations it be added that the vibratile substances which are commonly found to inclose the sensorium are not ill qualified to participate in the undulations of the surrounding medium, and carry them onwards to the internal seat of perception, the reader will be prepared to learn that the only essential part of the organ of hearing is a nerve, not materially different from those of common sensation, lodged at a sufficient depth to be secured from external injury, and sufficiently sensitive to be affected by these delicate impulses. This is called the acoustic or auditory nerve.

It is probable that even the lowest animals provided with a nervous system are able to perceive the notices thus conveyed of external objects, and turn them to account in the degree necessary for their security and comfort. But to meet the increasing wants and minister to the multiplied faculties of the more complete animals, various subsidiary parts are found to be . in something like a regular succession as we advance upwards in the scale, each lower grade possessing the rudiments of some additional provision more fully developed in the next above, till the organ reaches its greatest amplification and final perfection in man and the other mammalia. The particular use of many of these subsidiary parts has not yet been explained. We know in general that they must increase the force and vividness of the impression; that they afford indications of its direction, and the means of appreciating minute shades of difference in its kind and degree, and in the frequency of its repetition; that some of them add to the security of the organ without impairing its delicacy; and that others serve to adjust its position and to adapt it to various changes in the state of the atmosphere. It would be superfluous, in a work addressed to the general reader, and limited in space, to trace these gradual and complicated changes: we must content ourselves with noticing some of the most important of them, and then pass on to the description of the organ as it exists in man: advising the curious inquirer, after he has made himself acquainted with the details of that organ and with the classification of animals by Cuvier, an outline of which is given in a former part of this work [ANATOMY, CoMPARATIVE], to consult the admirable essay on this subject by Professor Grant, in the third part of his “Outlines of Comparative Anatomy,' where he will find a comprehensive and masterly summary of all that is known on the subject, from which we should be inclined to quote largely here, were space allowed and selection easy.

#. Radiata (star-fish, sponges, &c.), which constitute the lowest, and in point of variety and number by far the most comprehensive division of Cuvier, appear to be universally unprovided with an organ of hearing: many of them have no nervous system, and are therefore probably altogether devoid of the sense.

The Articulata, which form the next division, are all furnished with a nervous system, and it is likely that they all enjoy the sense of hearing. Indeed, some of them are able to express their feelings and wants to their fellows by means of peculiar sounds, of which the cricket and queen bee are well-known examples. We find accordingly, that in many of the more perfect species the extremity of the acoustic nerve is expanded upon a simple kind of auditory instrument consisting of a whitish membranous bag of fluid, placed within the head in a somewhat larger cavity, the space between them being also occupied by fluid. This cavity is situated near the outer feelers, or antennae. When the animal lives in water, it is commonly complete; if in air, there is a round external opening closed by a thin, tense and transparent membrane, showing the white colour within, to which the bag adheres, and which receives, concentrates, and transmits the sonorous vibrations of the surrounding medium. This kind of arrangement seems to be necessary, among other, reasons, for the purpose of indicating the direction of the sound, which is probably made known in part by the clearer vibration of the membrane when turned in that direction, and in part by a comparison of the impressions on the two sides; for this organ, like all others which bring the animal into relation with the outer world (as distinguished from vital organs), is always double

and symmetrical. It may be observed that the nerve dis-,

tributed to the membranous bag just described is given ol. by that which supplies the antenna with its exquisite sense of touch; some have thought, but perhaps erroneously, o the faculty of hearing resides in the antennae themSelves. - The parts we have enumerated are all found, with others, in the higher animals, and may be considered as the most essential o of an organ of distinct hearing. The cavity is called the vestibule; the soft membranous bag of fluid is the vestibular sac, the round external opening is called, from its shape in man and most other animals, the fenestra ovalis; the fluids within and without the sac are called respectively the endo-lymph and peri-lymph, (ovéov within, trepi around); the latter, being analogous to the fluid discovered by Cotugno in the internal ear of mammalia, is sometimes called, after his name, the liquor Cotunni. The principal tribes of the Articulata ascertained to possess organs of this kind are the air-breathing insects of tne orders Hymenoptera (bees), Orthoptera (grasshoppers), and Coleoptera (beetles); the Arachnida (spiders), and the Decapodous crustacea, such as the lobster and crab. In the common black beetle they are very conspicuous, aparing externally in the form of round white points on the head, a little nearer the middle line, and somewhat higher than the base of the long outer antennae. In the lobster they are contained in a small nipple-like prominence or papilla upon the under part of the moveable base of the antennae, looking downwards and forwards. This papilla consists of a substance harder and more brittle and probably more vibratile than the rest of the shell. The Mollusca, though placed higher in the scale of animals by Cuvier, do not afford so many examples of animals possessing a distinct organ of hearing as the Articulata. . Such as have been discovered all belong to the order of the Cephalopods with two branchiae, or gills, which approach more nearly to the true fishes in their structure than the other mollusks. In the Sepia, or cuttle-fish, which belongs to this order, and which may be taken as a type of the rest, there is a protuberance under the elastic gristly integument at the back part of the head which contains the ear. It consists of a pair of symmetrical vestibules, each containing an oval sac filled and surrounded with fluid. On the interior surface of this sac the acoustic nerve is expanded in the form of a white mucous pulp. The sac is supported in the perilymph not only by an adhesion to the inner side of the parietes of the vestibule at the entrance of the nerve, but also by a fine net-work of fibrils which pass from its outer surface to numerous prominent points on the inner surface of the vestibule. There is no fenestra ovalis, or membrane, as in the lobster and the air-breathing insects, but the sac contains a small loose bony or chalky concretion, called an otolithe (oic-dröc, the ear, and Aiboc, a stone), which answers the same purpose, namely, to indicate the degree and direction of sound; for just as we estimate a weight by poising it in the hand, or, if it be suspended, by gently pushing it from us—thus measuring in our minds the muscular tension necessary to support it, or the force required to overcome its inertia, and conscious of the direction in which we exert our muscles—so, conversely (the weight and inertia of the lapillus always remaining the same), the degree and direction of a vibratory force affecting it from without through the medium of the integuments, the parietes of the vestibule, and the fluids within, may be estimated by a consciousness on the part of the animal of the nature of the stress on the sensitive membranes and fibrils which support it, which by their elasticity restrain and redress the slight movements impressed upon it. This should be borne in mind; for, as we shall see further on, it is in some degree by the exertion of the muscular sense, as Sir Charles Bell has called that by which we judge of weight and tension, that the human ear is enabled to estimate the intensity of sound. Other curious particulars as to the function of otolithes might be enlarged upon; but we have said enough to explain, as we think, the most important of them; and to correct the misstatements of authors who tell us that they are intended to increase the intensity of the vibrations of sound: they appear to us rather calculated to diminish it, as the board floating in the bucket of the water-carrier tends to prevent the fluid from dashing Over the side. They undoubtedly play an important part in the organ of hearing, especially in the larger fishes, where they are more numerous, and attain a considerable size; but it is difficult to conceive that they are possessed of any intensative power. The vertebrated classes of the animal kingdom, comprising the true fish, reptiles, birds, and the mammalia, are all provided with acoustic organs, which are very various in their degrees of complexity, but much exceed in that respect the comparatively simple organs of the inferior divisions. * In the cartilaginous fishes, such as the ray and the snark, the vestibule is deeply imbedded in the elastic walls of the back part of the cranium, near its junction win the spine. The fenestra ovalis, closed by a tense transparent membrane, faces upwards, backwards, and towards the middle line. The membrane is placed obliquely at the bottom of a more superficial, flattened, tubular cavity, which terminates beneath the integument in a kind of forked extremity, and may be considered as a rudiment of the tymfanum, or middle ear, of the higher vertebrata, with its eustachian tube. The inner surface of the membrane is turned towards three sacculi, one of which is much larger than the rest, arranged at the opposite side of the cavity of the vestibule, and containing each an otolithe. The sacs are filled with a thick gelatinous endolymph, which adheres to the lapilli, and serves, with minute filaments such as those in the sepia, to steady them. The vestibule is filled with a limpid aqueous perilymph, traversed in all directions by a fine cellular network, by means of which its contents are supported in their relative situations. Besides the fenestra ovalis, other perforations lead out of the vestibule into three arched cylindrical canals of considerable diameter and dimensions, the diverging curves of which take a wide circuit within the cranial cartilage, and terminate at both ends in this central cavity. These passages, from their situation and form, are called the anterior, posterior, and horizontal semicircular canals. Within the canals, in which the vestibular perilymph freely circulates, there are three similarly curved but more slender membranous elastic tubes: they are nowhere in contact with the sides of the canals, but are suspended in the midst of them by means of the cellular network above mentioned. They all swell out at one end like a flask (ampulla) as they enter the vestibule, after which the anterior and horizontal tubes separately enter a common pouch or sinus; into this their other ends likewise open by a conduit common to both. The posterior tube, which is the largest and longest, after forming its ampulla, resumes its former calibre, and passing along the floor of the vestibule under the largest sac, to which it is connected by the net-work, returns into itself, thus completing a separate circuit. The fluid contents of the several membranous cavities do not communicate with each other or with the vestibular perilymph; though, as they lie in close apposition, their vibrations are mutually interchangeable. The acoustic nerve is distributed in two principal branches only to the sacs and the ampullae; chiefly to the latter, to which it gives a white colour. The filaments form a fine network on the outside of the ampullae, and then piercing their parietes, are raised up within into a kind of crescentic screen, in order probably that they may be more exposed to the impulse of the vibrations descending along the aqueous endolymph of the semicircular tubes. All the parts we have described are transparent, except the opaque ampullae and the solid cretaceous otolithes. We have been particular in our account of these membranous parts, which are found with little essential variation in all the superior animals, man included, because in the cartilaginous fishes they admit of more easy examination from their great size and firmer texture, and from the softness of the cartilage that encloses them. In man and the mammalia, they are not only much smaller and more delicate, but encased in the hardest bone in the body, from which it is almost impossible to separate them with sufficient accuracy to be certain that the description is correct. In some cartilaginous fishes, as the sturgeon, the fenestra ováis is not closed by a membrane, but by a round buttonlike piece of semi-transparent cartilage, called an operculum, or lid.” The parts are similar in the osseous fishes, except that they have generally no fenestra ovalis. In serpents there is but one sacculus containing chalky • Scarpa de Auditu. *This is also found in the aquatic salamander, which, as concerns the organ * healing, may be considered as the link between fish and reptiles, resem.

blog the latter in the arrangement of the labyrinth, but being unprovided with a tympanum or a columella.

matter, and all the semicircular tubes communicate with a central membranous sinus, which the anterior and posterior tubes enter by a common trunk. The fenestra ovalis is closed, not as in fishes by a membrane, but by the expanded trumpet-shaped extremity of a slender bone (ossiculum or colume/la) attached at the other extremity by a ligament to the outer end of the inter maxillary bone. Nearly the same arrangement of the internal ear prevails in the four-footed reptiles (turtle, crocodile, frog, lizard); but a new and important step is here made towards the ultimate perfection of the organ by the development of an aircavity, called the tympanum or ear drum, between the vestibule and the surface of the head. This addition, which, as we said, first becomes more than a mere rudiment in the fourfooted reptiles, permits the vestibule to be placed with equal advantage at a comparatively greater depth, and therefore in greater o but it has more important uses in rendering the sound more clear, and facilitating in several ways (to be presently explained) its communication to the auditory nerve. Like the musical instrument from which it takes its name, the tympanum is provided with a membrane tightly stretched upon the margin of a round opening in the outer part of its bony or cartilaginous wall; and has an open vent or passage called after the anatomist who discovered it, the Eustachian tube, leading forwards from the cavity to the throat or back part of the nostrils, by means of which the air within it is adjusted to the variable state of the atmospheric pressure without. If the animal be amphibious, as many of the four-footed reptiles are, the membrana tympani is still covered entirely by integument, sometimes, as in the crocodile, by a movable flap of the scaly hard skin, which can be raised up when the animal is out of the water: more frequently however the membrane lies entirely beneath the skin, here thinner than elsewhere on the head, as in the tortoise. The lacerta agilis, or basking lizard, alone, which lives entirely on the land, has the membrane naked to the air. In this class of animals the columella is not directed forwards to the angle of the jaw as in serpents, but is attached by a cartilaginous extremity to the centre of the membrana tympani, and thus conveys the collected effect of its vibrations directly to the fenestra ovalis: the effect of this arrangement in rendering the impression of sound more definite must be obvious. In some species the cartilaginous portion of the columella is joined to the bony portion at an acute angle, like the letter V, which adds an elasticity to the mechanism very serviceable as a protection to the delicate parts within the fenestra ovalis from the injury they might otherwise sustain by a blow or undue pressure upon the membrana tympani. This is the case with the lizard mentioned above, in which there is also a rudiment of the muscle which serves in the higher animals to tighten the membrane; a circumstance which makes this elbow in the columella a still more essential provision against sudden changes in the distance between the centre of the membrane and the fenestra ovalis. It is worthy of remark that in one class of serpents, the carcilia (blindworms), the ear is as complete as in any of the fourfooted terrestrial reptiles; possessing a tympanum with its membranes, a Eustachian tube, and a columella bent to an angle. This departure from the usual rule in serpents appears to be one of those compensations so frequently met with in the animal kingdom, the organ of sight in the caccilia being imperfectly developed. In birds, besides a greater nicety and tenuity in the conformation of the parts hitherto described, the ear is furnished with two additional provisions, both probably of great consequence to the perfection of the organ. The first is a short meatus auditorius earternus, or outer passage, which removes the delicate membrane of the tympanum to some depth from the surface of the head, and thus places it more securely, and at the same time, to greater advantage for observing the direction of sound. The other additional provision in birds is an appendage to the mechanism of the internal ear. This is a small conical cavity in the bone, somewhat curved, with a double spiral ridge winding round the interior, and enclosing a cartilaginous structure so corresponding in form with the ridge as to divide the cavity into two partitions. These communicate with another at the apex, and with the vestibule and tympanum respectively, at their other ends. The cavity is termed the cochlea, from its resemblance to a spiral shell; the partition communicating with the internal ear is the scala (winding stair) of the vestibule; the other is the scala tympani; the open

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