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Lat Imagat lulvsntas ont M raprodultai avac la plus grand toln, compta tanu da la condition at da la nattata da raxamplaira filmi. at an conformM avac lai conditions du eontrat da fllmaga. Original copies in printod papar eevars ara fllmad baglnning with tha front covar and andlng on tha last paga with a printad or illustrstad impraa- slon, or tha back covar whan appropriata. All othar original copias ara fllmad baglnning on tha firat paga with a printad or illustratad Impraa- sion. and andlng on tha last paga with a printad or illuatratad Impraasion. Las axamplalras orlglnaux dont ia couvartura an paplar ast Imprimts sont filmte an commangant par la pramiar plat at an tarminant aoit psr la darnltra paga qui comporta una ampralnta d'Imprasslon ou d'illustratlon, soit par la lacond plat, aalon la eas. Tous las autras axamplairas origlnaux sont fllmto an common9ant par la pramlira paga qui comporta una amprainta d'Imprasslon ou d'illustratlon at an tarminant par la darniira paga qui comporta una talia amprainta. Tha laat racordad frama on aach microficha shall eonuin tha symbol —^ (moaning "CON- TINUED"), or tha symbol 7 Imaaning "END"), whichavar applias. Un das symbolas suivants spparaltra sur Is darnitra Imaga da chaqua microficha, salon la cas: la symbols —^ signlfia "A SUIVRE ', la symboia V signlfia "FIN". Mapa, platas, charts, ate., may ba fllmad at diffarant raduction ratios. Thosa too larga to ba antlraiy includad in ona axposura ara filmad baglnning in tha uppar laft hand eomar, iaft to right and top to bottom, as many framas as raqulrad. Tha following diagrams lllustrata tha mathod: Laa cartas, pianchas, tablaaux, ate. pauvant itrs fllmta A das taux da rMuction dlfftrants. Lorsqua ia documant ast trap grand pour ttra raproduit »n un saul cliche, II ast film* t partir da I'angla auptriaur gaucha, da gauchs 1 droits, at da haut an bas, an pranant la nombra d'Imagas nAcsssaira. Las diagrammas suivsnts iilustrant la mtthoda. 1 2 3 1 2 3 4 5 6 MKtOCOW RISOIUTION TUT CHAIT (ANSI and ISO TEST CHART No. 2) 1.0 la ^ ^m m III 1 I.I ,.25 1 J -APPLIED IIVt4GE In, .*> tl!. rvS'Y WOOD. S WMlTtH«LL COUHT, l-ONUON. S.W.I, Co«vY.\.'\.'Cft,C'ft,X» o^ The Eyelids and Lachrymal Apparatus of Birds DR. CASEY A. WOOD, Chicago, III. (REPBINTED FROM OPHTHALMOLOOT, JULT, Itlt) THE EYELIDS AND LACHPYMAL APPAHATCS OF BIRDS. Caut a. Wood, U. D,, OBICAOO. Illuitratid. The amngement by which the iDterior surface of the eyclHill ci Birda i> cleanaed and uthenriae protected from rarioua forma of Injury difftra matarially from that vhich one flnda in other Terta- bntaa. Eren ttr thoae who are not ipaciaUy intareated in compan- tire anatomy and phyaiology it often many pointa of contact with hnman ophthalmology, and thia ia the writar*! chief axcuae for thia artiela. Moat of the inreatigationa that form the baaia of thia paper ware made in the phyaiologioal laboratoriea of Stanford tTnivera- ity, ia coojonction eapacially with Profeeaor Slonakar. The raaolta of theie letearchea ware Srat reported to the Ophthahnological Con- gieaa at Oxford in July, 1914, and publiahed in the Americm En- cueleptil* vf Opkthatmohgj/, to whsae pobliaber the writer ia in- dabtad for the iUnatrattoaa. That one may appndate the part pkyed by the eyelids and the lachrymal apparatna in the vlaion of birda it ia eaaential not only that the aecretion and lamovat of the tear* ahoold be atndied but that the diapoaition of thr bulbar and palpebral mnaclea ahonld be borne in mind. The tfU§niu4 oovaring the avian ayaKiit is more homy than in man. It ia attached to tha «or: ai by dalioata flbrea. The (ami plait of the letaar tU ia compoaed of cloaely packed conaectiTe-tiaaaa ilbrea, in which one occaaionally Unda ipindle- ahaped or round cellt ; but none of these can properly be described aa cartilage calla. A dalieate network of reaaela snmnn i the tar- sal plate. In some birds a fatty layer, more or lees marked, is found in a well-defined space between the lid edge and the upper margin of the tarsus. The occompanying illuatration shows the lid margint of the Sparrow to be compoaed of about 34 (17 in each lid) deeply pig- (RBPRIIfTBD ntOK OPHTHALHOLOOT. JTJX.T, ItlS) « t'M«y A. Wood, nicntiKl, irregular. Muugc-likii, wgmnnU. They are offen ileeplv indcnW about lliiir middle, thui preacnting a picture entirely unlike the I ' edgea of man. These legmonta undergo, during life, apparent djangea in tiic and shape, probably aa the reanlt of winking, partial or complete. Close inspection u{ them shows that some of the?u segmenu are ^^^'"MjfiAii' '','??„55''.id%i:rkrrr"' °' "" "••"■"■ """' '" "•' ""■ crossed by indentations which may become entirely smooth again ; other parts, smooth and rounded a moment before,, may present a creased or divided appearance, so that photographs or drawings of '-''5 "I'i'lipJPi"™*' «'->'?--''"D'i.'ig-fe8ult« ao.fsr, aa the mai-giu.i of the lids are concerned. In Passer, as i' most birds, there is no well defined intermarginal apace. A feather (eyelash) is geuerallv placed below each palpcbr^! segment, but the former may bi; misi- Kfirftth and Lavhrifmal .\ ppanttit* of Hirdu, \ng »\ the outer and innor cin'l.i, while otmr tu(ta ii avallin-l over the lid lur/iice. The inttrjat tbml ipace viriei koinewhat in the itptrrow : [kt- hapii it is a litue mure circular and smaller whi'n tho bini wH'om- moilut"- ':r near viiion. 'ITie acconipunyinK illuatralinn jjivM .in idea of thu average relative tizc of the pupil and of the inlerspai'i! during fixation for a near object. It will alio be noticed that thia ipaco ia entirely filli'il ,iy ihi' Sparrow's cornea, a condition i;ntirely unlike tliat in mammala. The space is 8.9 mm. wide and 4.5 mm. long. There is no lachrymal caruncle or anything to indirate it, nor would one exixvt it if the higher vertebrate caruncle be a veatigiary remains of tlii. n. titating membrane. In the great majority of birds we, for obvious reasons, do not speak of an internal and external canthus but of anterior and potterior canthi. In Sparrow-like birde the pigment of the rounded, dark brown lid border does not extend beyond the point where it touches the ryeball, nor does it more than reach the nalpebral derma. There is more pigment in the upper lid than in the lower. When closed, the junction of the two lids is well above the pupil, so that the cornea is fully pro.ected. Probably there is no upward rotation of the eyeball in sleep. The lower lid follows the usuel law in biriN, of being the movable one. As a general proposition it may be stated that in resiwct of sizi'. motility, etc., the lids in the Bird and Man are reversed, viz., the lower lid is the more important in Birds; the upp^r lid in human beings. The naked condition of both avian eyelids is not seen when the eye is ipen because the., are then obscured by tlie surrounding feathers. The external surface oi each lid is quite thin, smooth, whitish-blue end devoid of feathers, except for a few solitary shafts. Very li! y there is no interference with the luminous sense and light-direction sense when the Bird's eye is closed. There is no differentiated tanue in the upper lid, which is much shorter and thicker than the lower one, although the ronvoluted cylindrical margin of the upper lid is better shown in the upper than in the lower lid. Unlike Man and many other mammals, there is no true union of the conjunctivae of the two lida before the bird is bom. In the Sparrow (probably in 1 the Passeriformes) the lids are wide open I ♦ Cauf .1. Waa.: evidence Ui.t „y oigwiio union occur, betwwm the lid m.r«in. in h«, ..born-blind" bird. In .„ probubility U.. cl„«d e^ZZ to tonic contr«tion of the orbicul.ri. u , Jlght reSe, „t ;,I "T't' "' '*' •*""• *" "" o^<"''<^ palpebrarum, the >'<^orpalpel,ra. „p.Won., .nd the d.pr^„ ^'^fr^ inMorU A«ording .0 Leuck.rt (Ora.f^Sa«n»ch HandiJk d. g,. Aug^. hnlkunJe, Vol. II, 1876, p. US) ,„d Doenecke, they .re ,11 .tri'ted Zt^ i^'Z"- ■' P- "»> *«"««» **« orbicuUri. to be , (M one might expect from the f«t th.t the l.t.er i. more mobll. U,.n he upper .nd Utter developed than the levator of the uppe lnlT^« 'IJ^*?.""™"^ "'" "" ""«"" ■•"'•" <" the lid pUto ." ioint^ .11 •• •''"°"l"'« '" Ziet»chm.nn both muKle. J„™^ ™!? V "'"*" '" "" "^P"" "' ">» o"-'*. where they form p.rt of . common muicl. mu.; .Ithough Slon.ker h.. not b«n .ble to verify thi. finding. 81on,ker, however. ag«« Uh Z.e.^hm«,n th.t the orbicuLri. i. , .mooth m„«i;,^. ^ ' the depreewr .nd levator p.lpeb™i are .triated. thirH °7'7™"",« '^"' ""o Sparrow tlie writer found that the the bird. eye. The paire. U,. .lo« very .lowly, if at ^I under the . imulanU u«d. The phyi.ological e/periment. bear out wh! IHZ^T""'"'- '"■' '■'"' ""' "'"™""*' " --""ot „,«?iL°''*'"l'''~ " "' "'"°"'^ **" "»•«'« i" th" Sparrow a. may be «en by examining the «x«mp«,ving flg„„. u ^pe„ ° mere hno. on horizontal .ection, and ^'Jn ToU in eS L^ t.on,. It ,. attached to the .kin and doe. not, a. in Man nprL out and mingle it, fib,« with neighboring for,.h.ad. ta^uMofTh lower hd) and lachrymal apparatus muscle. ' Jffird'lVrV'^J"^ " "" ""•" ™"''' -"»«""• -">■ «■«•''>«••' i" tnc Bird 8 hd of the human muscle of Eiolan. .Mthough tteie i. every reason to believe that the non-striated or- bicularis of Pa,>,er domesticm is supplied by fibre, deri™- * ■di "'„'!"'• "r^— '™«»g the cou^ of'theTb,; and d,^.™n,ng their origin, has not yet been solved. In the Hen the ciliary f„tKer,, or eyelashe,, mom nearly re- -n... • thi.k, .^,^ |„i„, ,„,, ,hi, ,„„,,„,,|„„,„ „ ,.,,^,h^,„ I. .11 Ih.. in,.™ pron„un«,l in th.t th,.«^^ IHirom, f,.„ih..n. ,„• in. point. intiTl.,,, with thi. I..I,,.. I f,.„,i ,,„., , , ,; f Mo„K.vor, wh«„ ,h„ lid. .,„ el,*.,! U,„ inrnT li.l-.n.rlL roll i "...r. than ,. U» ™., „l, ,l,„ S,«„„w. „, tl„t ..,.. i„l™« ' '" rh:ri:Mr'"^-'-"- ""•"'""• ""•'^- '"-" TlH« f..thor.t..vel«he. belong to th.- .l.,,. „f ,i|„,,|,„ „. th«...l f. ..her. With no true v.ne., thirty to .hi.tv-Hv.. !,1 Z J, •nd «l;„.'i:;r'',""""' ■•■>■•■ " ""■ African u.,rlch_s,ru,hl„ o.mel,,.. ,w,„d more being found in the upp..^ lid ,h.n in the lower. Of „„mv ob«rv. ,„n, the writer found the average p,.^,r,i„„ ,„ ,„ ,, T In n,„«t ,n8t«nce, the plumule of the ,uft rine. ju.t «l«ve the J,rt n..rg,n o, .he eyelid and i, bent or direeted awav fr„,„ the 1, er L two eanth,. The plumules do not n,«.t or fom, a gcnen over th.. Z^Z T", '"'''"'"'"' "" '""' »"• «"""''>■ wanting or a„. in^rted irregularly „me di.Unee /r«m the margin „f L li^ • C(u$p A. Wood. At the inner ciintbus and especially on the lower lid the cUiary tufts are (to the number of 5 or 6) directed straight forward. Scattered over the two otherwiie naked lids a varying number- usually half a dozen-flf plumules can generally be seen of the same size as those at the lid margins. Sometimes, though rarely they form a regular second row of cilia along the margin of the lid.' The eyelashes of Sparrow-like birds do not, judging from their position relative to the lid margins, act as a protection to the eye An examination of them shows they are not prominent enough for this purpose; they are too far removed from the interpalpebral space; they do not overhang the lid margin, and they do not intei- to^k when the eye is closed, as in many of the other vertebrates They appear in bird life to occupy a place intermediate between the Ostrich, Seriema, and other birds that possess well-developed and useful eye protectors, and the Parrots that have none at all. Nevertheless the cilia of the Sparrow are more developed than in some other Birds, though less so than in the Ostrich, Sc. ..ma and the Birds of Prey. The eyelashes of most Birds do not lake much if any part in the protection of the eyeball during sleep or on other occasions. The Sparrow does not entirely close his paited lids unless the cornea is touched with some blunt object, as a dissecting needle, although any approach of the object increases markedly the contractions of the nictitating muscles. Except during sleep, or in particular emergencies, the paired lids of Birds are rarely closed. Most of the ordinary functions of the human lid are performed by the nictitating membrane. The true lids of the Sparrow may indeed be regarded as accessary organs whose functions are confined to the protection and moistening of the bird s eye only while he sleeps. The writer and Slonaker have not been able to observe the Sparrow with his third lid drawn over the globe (without closure of the paired lid margins) during som- nolent hours, as is said to be the case in some Birds of Prey the Hen, etc The soft sausage-like rolls of each lid-edge approach one another and close the interpalpebral space in a fashion entirely unlike the eyes of the higher vertebrates. However, even when the edge of the third lid is incompletely drawn over the globe the edges of both hds make slight but quite apparent efforts to close, as if here were slight contractions of the marginal fibres of the orbicu- laris. These winking efforts are more marked when the membrane sweeps entirely over the interpalpebral apace; but in this consemmal ^ylids and Lachiymal Apparatus of Birds. 7 contraction of the true lids their margins do not approach one an- other, and, indeed, rarely reach the sclero-oorneal junction. The intcrpalpebral line of closure in small Birds is irregular in- terrupted and wavy; nor are the two intermarginal spaces accurate- ly opposed to each other, as in Man. The Sparrow probably does not oppose more than one-half his lid-margin in the act of eye- closure, but shuts off his conjunctival sac from the outside world »ul«rl. muscle flbrerit the iL' Po n.™ Slii I? "H"* "■S"""*"'' O^ "■■'>'- of the Irl.; Rp°rS-lVe n.d ■„? th? y;„..'5''" """"^ >}">■ ™'11«1 muscle. 8P, .upenoV pSipete. ^'„,''c'i2:''T',',l'r.'uTb,'uv™rui^i.p¥.'r nt"' "'"■"^ * ('aee) A. Wood. by pressing the soft, convoluted marginate rolls into one another. The difference between lid closure in the Sparrow and most of the higher vertebrates is, roughly speaking, that between a roller-desk cover and that of the mouth of a tobacco pouch. The movements of one nictitating membrane (or third eyelid) is in most birds probably independent of the other, although they generally act together. In an adult, male Sparrow, whose cornea had been irritated by manipulation, the average nictitations of five-minute observations was 55, while in the fellow eve the winking was reduced to 47. In a darkened room the number'of nictitations fell to 41. The extremes of numerous observations under various conditions of rest, darkness, bright illumination, after the Bird had flown about the room, after irritating the cornea, etc., were (during rest) 33, and (during exposure to direct sunlight) 01. Under the last named condition, while" the nictitating membrane was drawn over the globe rapidly and completely, it was returned to place very slowly, so that the eye was covered by the membrane during a relatively longer period than usual. In most Birds, the lids of the Sparrow's eye close immediately aft«r or just before death. This, as is well known, is entirely dif- ferent in Man and many other Mammalia; and the explanation is that the lid-closer is really a smooth, sphincter muscle innervated by the sympathetic, which continues to act after the departure of consciousness and after the eye-openers (innervated by striped muscles) have ceased to be under control of the will. The sensory nerve supply to the lid is also entirely different from that of Man. Slonaker found that it is from the lachrymal branch of the fifth nerve only, which, after giving off branches to the lachrymal gland, divides into two porUons, one going forward into the lower lid and uniting with the superior maxillary nerve. As yet unverified is his belief (from dissections of the parts involved) that minute branches from what he calls the frontal nerve may send sensory branches to the conjunctiva and to the skin about the external canthus. One of the most interesting organs of the avian eye is the third eyelid or nictitating membrane, Fumagalli has furnished an elab- orate description (Intemat. Monatschr, f. Anat., 1899, p. 1S9) of the minute anatomy of this membrane, as found in the Hen and Pigeon. Slonaker and the writer have not, so far, entirely investi- gated the nerve and blood supply of the Sparrow, but agree with Fumagalli and other investigators that the nictitating membrane ff;/c/i'rf» and Lachrymal Apparatus of Birds. 9 is composed of (1) an anterior epithelial layer, (2) a middle con- nective tissue layer and (3) a posterior epithelial layer. The anterior epithelial layer has the appearance of typical pave- ment epithelium. The deep layers are more cylindrical in form while the superficial are more flattened and show oval nuclei Pigment cells begin in the deep cells but get less and less in amount as the surface is reached. The middle layer constitutes the true substance of the nictitatin.' membrane and is largely made up of elastic fibres interwoven with connective tissue fibres. The former are most numerous immedi- ately under the epithelial layer. The middle layer is provided with numerous blood-vessels, nerves, and a number of tubular, solitary glands. Slonaker and the writer have not been able to find the latter in Passer, but we do recognize there glands which are some- times straight, and sometimes globular, like sweat glands. Their openings are on the anterior surface of the membrane. The posterior epithelial layer is composed of cylindrical epithe- lium two and three layers deep. The deepest cells are polyhedral in diape, while the more superficial have long prismatic elements This layer of the conjunctiva is finally continued as modified ante- nor corneal epithelium. According to FumagalU, the elastir fibres of the third lid run in all possible directions through the connective tissue bundles to fonn a thick network, which may be resolved into three layers Puriiennore, a bundle of these fibres is shown extending from the base to the apei of the lid. It lies in the deep portions of the con- nective tissue, directly on the posterior epithelial layer. From this deep, basement or foundation layer of larger fibres there stretch at right angles to it more delicate fibres through the whole width and thickness of the membrane, and terminate in the cells of the ante- rior epithelial layer. This strong, deep-lying bundle becomes thicker the nearer one approaches the free border, until it forms two or three fibrous bundles measuring 123 microns wide that eventually becomes part of the tendon of the pyramidalis muscle. Fumagalli finds that posteriorly the elastic connective nerve-fibre bundles are so disposed as to form a subepithelial network from which still finer fibrils extend, some of which terminate in end- corpuscles. Slonaker and the writer, after considerable time spent in an in- vestigation of the subject, conclude that the nictitating membrane 18 a conjunctival duplication— a thin, translucent membrane com- 10 Catey A. Vfood. The free margin of a portion posterior to it is set with pigment posed of delicate connective tissue interspersed with elastic flbna running in various directions. It has a firm, thickened, free mar- gin, but no hyaline cartilage cells. This latter provision enables the free border to be closely applied to the cornea, so that when it sweeps over the latter it carries with it some of the fluid secrotion of the Harderian gland and thoroughly cleans and uioistens the corneal surface. The presence of elastic fibres gives to the third lid the qualities of a thin rubber band ; when put upon the stretch it flies back instantly the moment the traction or "pull" is released. «, ?"'*■ * — Enlarged Camera Drawings Showing tile Marginai Plait of tile Nictitating Membrane, Botti Extended and Compressed. (Wood and aion- aker.) MP. Marginai plait; NE. epltiiellum of tlie nictitating membrane: CE. conjunctival epithelium; LE, lid epithelial lining. cells, but this marginal pigmentation is much less marked in the Sparrow than in other birds — the Snow Goose and Ostrich, for instance. A sectio- . the third lid at right angles to the free border (sec the illustration) shows the latter to be triangulir in shape, like half an arrow-head, and to be thrown into folds both on its anterior and posterior surfaces. Interesting, also, are the basal folds of conjunctiva, somewhat like the folds of transmission of the human conjunctiva, disposed so as to allow of considerable and rapid excursions of the membrane back and forth over the eyeball. Efelidt and Lachrymal Apparatus of Birds. 1 1 In the study made by Slonaker and the writer on the eye of tho Sparrow and other Birds they found Slonaker's marginal plait (see cut) not only in numerous sections of the Sparrow's third lid, but in all the other Birds so far examined ; it is certainly well marked in such unrelated species as the Sooty Tern, the Red-Headed Wood- peclcr, and in various Pigeons. Strange to say, Fumagalli (Ueber die feinere Anatomic des dritten Augenlides, Intertiaiional. lion- atstchr. fiir Anatomie und Physiologie, Vol. 16, p. 189, 1899) makes no mention of this important structure, and, although the whole subject is by him elaborately illustrated by well executed Ldo I the work of FumasalH, the lower i plates, he pictures the Pigeon's accessory eyelid as lacking in the marginal plait. All vertebrates possess at leaut six extraocular, bulbar muscles- four recti and two obliques. Birds have two more (that control the movements of the third eyelid) viz. : the quadratus muscle and the pgramidalis, which are inserted into the posterior hemisphere, bo- hind the scleral insertion of the recti muscles. Confirming the observations of Kalt (Encyclopidie francaise d'Ophtalmologie, Vol. Ill) and others, Slonaker and the writer 12 Caseff A. Wood. found the quadrate muscle to be larger aud better developed than the pyramidalia. The muacultu quadratua a inserted into the sclerotic just behind the insertion of the rectus superior muscle. Its attachment fills in the space between the superior and internal recti muscles on the superior edge of the latter. From this insertion all its fibres are directed toward the optic nerve. The free extremity of the quad- rate muscle is about one-third as large as its size at insertion. Cv.u- sequently it pi'esents a triangle with a truncated apex rather than a square, as its namr indicates. At this point, instead of having another insertion, fixed or mobile, the muscle abruptly ends in a tendon which folds on itself to form a fibrous loop, intended for the passage of the pyramidalis tendon. Fig. 6 — Posterior View of the Left Eye of the Sparrow with the Reotuti Superior (Re), Inferior (R inf), Externus (Re), Internus (R In), and the Superior (OS) and Inferior (01). Oblique muKles laid back to show th« arrangement of the Quadratus iQ), Pyramidalis (P) and Tendon (T) in relaUon to the Optlo Nerve (Op), x 8. (Wood and Slonaker.) The pyramidal muscle, which is much smaller, is inserted under the anterior half of the inferior rectus muscle and on a line 3 or 4 mm. in front of the edge of the muscle. It then reachep the ante- rior surface of tht aptie nerve and ends in a tendon which passes through the loop encircling the superior surface of the optic nerve, then enters a groove in the sclerotic, wht it is held by a contrac- tion of the capsule of T^on. It then passes from within out, be- tween the inferior and the posterior recti muscle — ^nearer to the latter — interrupts the bony circle about the nerve (in tlie Owl it is Eyelids and Lachrymal Apparatus of Htrds. 13 attached to aa spophyeiB of the bony circle) and readies the ihm- tcrior-inferior angle of the third eyelid, to which it ii joined and of which it formed an integral part. At this point the (flat) tendon of the pyramidaliH lies in a groove — almost a tube — on the eyeball. It now enters behind the conjunctiva, pierces the lower sac at a point slightly posterior to the median plane of the eye, and is attached mostly along the free border of the third lid, aa a rope is bound to a sail. The fibres of the tendon are, some of them, also spread out fan-like and are lost in the tissues of the nictitating membrane. As the posterior-superior attachment of the third lid to the globe is posterior to the vertical plane and well up in the superior cul-dts Fig. 7 — Posterior View o'.' the Left Eye of the Sparrow Showing Ar- rangement of MiiBcles and Gl^ndB. x 8. (Wood and Slonaker.) L. I«chrj-aial gland; h. Harderlan gland; re, rpctus externua; rl. rec- tus Internua; r inf, rectus inferior; rs, rectus superior; oi, obliques Inferior; OS, obliques superior; q, quadratus; t, tendon from pyramidalis muscle to nictitating membrane; op, optic n^jrve. sac, it will be readily seen that the down-and-out puU of the tendon of the pyramidalis must cause the free border of the nictitating membrane to glide over the globe toward the posterior canthus. In ordinary contractions it seems to be drawn over to the sclera. Like the external rectus, the quadrate and pyramidal muscles are innervated by the sixth pair. Generally speaking, the oculomotor apparatus of Birds' eyes is not endowed with great power and the movements of the eyeballs are much restricted. The protective muscular apparatus is, how- ever, highly developed. 14 Co*'* A. Wood. l» free of foreign matter .„dT.T* ^ """"■' ^ """ " •>>»" «;e Sp.rrornicti^,;-;:^^7-;'-' • 2 *« '™ '"««*■' »' the npper cul-de-Mc In tw. , ^ .*' ™ "*■"«' ""d tow.rd befor,, behind ind .t L ^JL K ™°""""' '''""' ™«'«J the dm figure the ,ligh v ot^en.i """J""''"™' ^P-"»"'""- '» general ouUine of th bart ofTflll' 'T^^" '""'" P""""" 'h" of it. fluke, cut oi clo'^to th,Tfr V; "' n ""'■" '"" "■"' ing parts are interesting It wn..w .„ ,. . process or band is obliterated by then'' "' "?" "'"'" '^'""•' *» muscle when the membr^e i. " "'V^'^'""' ™ " »' *e pyramidal detritus (mixed ™Str H T*" °'""' "'"»™-^''- The corneal before the shelfo.g™t^t„f"tret:Z'""'r.' ^ *"" """'^^ or the sharp mar^n ofTli^: inT^.V"'^ " "■^'- -""^^^ P-ivetd" h" Sr™ *' "■ """"^""' »"" ''-^™*- =- tion is apparent The f,''"'.*" '- '"«on, a quite different condi- PParent. The marg,n of the pectinate fold now rises and HyMd. .ml LochrymalAppaniu, of Bird,. U «tera.l inrfMe of the thin! IM rin!i T? u '" ■"•■■«'" »»'' the entrance of the «h™^, li"' Th " ■ "* '?"""''> "'""•' 1899 and^„*.™«<. Vr^r /^^ '' (Wi><«.. Leipzig, iieei;ti:^Sor4°r'a:'/Vtf ^^^ ^''^"'^'" -^ «'«>" ope.. Mo. t. ^^:^r^zr^^f:^:^zzi u Ciury I. Wood. the ^«ted product i. ,i«id. Thi. gl.nd i. l,rg„ th.n the l«h. rymal glwd. .nd belong, to the tubul.r..l»eol.r type According to S.rdemwn (Britrig. ,ur Anatomi, der Tr«n.n l.« in the outer ,ngle of the eye .bout the e<,u.tor of the glo^ T!, ",'*''"' ™P""'««»'li" "'lobular .tructure. In.ide e.ch obule one find, .collecting .p.ce connected with ubul.r duct i™:f,.lt'°. r "'" ""■"' " "' ""■"■ ''''" ^ "' In the Hen the f<,«,r ,analiculu, i, the ,ni.ller of the two cnal. cnthu.. It, flattened opening, continuou, with the ponp.lpebr.1 .hf'£.c«i-c^'„-.VU"'ReSX'f n"°<«"AF«-.. w.n. or fZttatr"! ' """■ '"'• ^^ ""P^^ o^iculus, separated from ,te fellow by a narrow bridge of tissue, ban an opening about jmd .t,ll farther toward ihe front „f the beak than the low,:,- „,«„. t.nee'of7r''"rh'" fb" ""'"' """" ""^ '''° ™""'' ^^ ' <"-- tanee of 3 mm., when they join to form th,- lachrymal duct whose » .bre .s^ual to that of the combined upper ^d lower c a.Mcut tZ^^^"''^^' ^™ *"" "O *«"- '"C P o tt n.re., the l.chrvm.l duct of Bird. ha. little to do with the n.« PM-ge., but i. .„ i«,l.ted tub. crried through and p«t he nZ ^l!r,h?» ^^ "?' " ""^ """y- " '• -"» known, i. , M, maxlllKry alnuB; T. turblnala ' * ""*'* *'■■ '>•«'» cut away; tte ;u^o ll °^"'^ ™ "^ "'^' P^"''" ^^o-' lading to ^ttl „ T'"f ' '"''™"-^ '"*™'^'"^ " '««^«'»'y drainage t^ZlZT^l '"'''"" "" "-^^"^ '"^ -chn^ai^retiol The orifices of the c.nalicnii, upper and lower, are, as stated no^ placed on to lid margins at the anterior canthis, b^t "neraU; Mmute shallow grooves, b. ■ .wn in fte Hen, lead from the canthns around and close to u.e margin, of both lids and " » C—f A. Wood. gnttai^llka cooduit iot the purpoM o( convejring tha lichrym*! fluid in tha dinction o( tha pnih.'te. Tkaaa opaningi *ra ralitivaljr luja ud alnyi commnDinta with aomapondinglj luft oumlienll, whidi in Uw Sparrow ara about 11 mm. long. Thay Join tu (orm • laiga fibroua tuba, linad with apithalinm, tba lachrymal duct, that runa diractly downward and forward toward tha madian Una until it opani into the choanal ilit, tha marginata ipinea of which diiact ita contcnti backward into tha aaophagaal opening. In tha Sparrrw a probe 1 mm. in diameter can readily be paaaed through the lachrymal duct and thii probably reprcaenta the lumen of the tube. The canaliculi are about 1 mm. long, while the length of the common duct may be let down aa 3.6 mm. Slonakar and the writer have not Ik n able to demonatrata the prcaence of ciliated epithelium in the duct mucoca. The opaninga analogiua to the human puncla are irregularly rouuded; tba upper one being diitinctly larger and uore patent than the lower. Correaponding to theae, Slonaker*! ptripalpehral groove ia deeper, longer and better marked at the conjunctival r '■ gin of the upper lid than at the correaponding border of the lower lid. The principal facta to be remembered about the lar° i drain- age in Birda ara ( 1 ) that tha free margin of tha third , anchor> or balf-epear-ahaped ; (2) the free edge probably pn « before it — icraper-like — the Harderian fluid, thui cleansing , i cornea on the contraction of the pyramidalia and qkjdratua muacies; (3) at the instant of reat ihia same secretion, supplemented or not by the lachrymal fluid, is pulled (bucket-like) back and emptied into the canaliculi; (4) during thr erformtuice of this act it ia to be remembered that at he end ol '■'sa the most complete excursions of the nictitating membrane the lower edge of the lower lid ad- vances only about half a millimetre, whiU, although there is a aimultaneoui twitching of ita palpebral margin, the upper lid ap- parently does not come forward at all. "Ophthalmology" EHftrt, Abitraota and SUvUws The Intamatlonal Quartarl7 B7« Journal, owned, edltad and publlihed b7 and tor the proteBBion. 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