,transcriber's ,notes ,italics text has been transcribed between underscores4 ,small capitals have been replaced with ,,all ,,capitals4 ,more ,transcriber's ,notes may be found at the end of this text4 ,the eye--it cannot choose but see4 --,wordsworth4 ,illustration3 ,brain1 showing eyes with muscles removed1 optic nerves1 and chiasm4 ,,technique ,,of ,,eye ,,dissections ,,by ,,frederic ,a4 ,,woll1 ,ph4,d41 ,associate ,professor1 ,department of ,hygiene1 ,college of the ,city of ,new ,york2 ,optometry ,courses1 ,columbia ,university2 ,member of ,new ,york ,state ,board of ,examiners in ,optometry2 ,honorary ,member3 ,american ,optometric ,association2 ,state ,societies--,alabama1 ,california1 ,connecticut1 ,kentucky1 ,maine1 ,massachusetts1 ,north ,carolina1 ,rhode ,island2 ,local ,societies--,lehigh ,valley ,society of ,optometrists1 ,mahoning ,valley ,optometrists' ,society1 and ,optometrists' ,club of ,brooklyn4 ,,second ,,edition ,illustration ,,new ,,york ,,frederic ,a4 ,,woll #aibd ,,copyright1 #aiad1 ,,by ,,frederic ,a4 ,,woll ,printed in the ,united ,states of ,america ,first ,edition1 ,july1 #aiad ,second ,edition1 ,april1 #aibd ,,schlueter ,,printing ,,co41 ,,new ,,york ,,dedication ,,this ,,little ,,book ,,is ,,dedicated ,,with ,,affection ,,and ,,esteem ,,to ,,my ,,first ,,teacher ,,in ,,optics1 ,,my ,,friend ,,for ,,years ,,andrew ,,jay ,,cross ,,whose ,,research ,,in ,,the ,,field ,,of ,,applied ,,optics ,,has ,,won ,,for ,,him ,,recognition ,,and ,,honor ,,contents ,,page ,preface #ac ,introduction #ag ,removal of ,hyaloid ,membrane with ,contents and ,attachments ,intact #be ,canal of ,petit1 ,the #ce ,interior of the ,eye1 ,the #ch ,posterior ,half1 ,the #dj ,optic ,nerve1 ,the #dg ,anterior ,half1 ,the #di ,iris1 ,the #ea ,cornea1 ,the #eb ,crystalline ,lens1 ,the #ec ,choroid1 ,the #fb ,retina1 ,the #gd ,sagittal or ,vertical ,section of the ,eye1 ,the #hf ,papilla1 ,puncta ,lacrimalia1 and ,nasal ,duct1 ,the #ib ,meibomian ,glands and ,ducts1 ,the #if ,enucleation of the ,orbital ,contents1 ,the #ig ,ophthalmoscopic ,examinations #ajf ,lacrimal ,ducts1 ,the #aab ,lacrimal ,gland1 ,the #aad ,capsule of ,tenon1 ,the #aae ,superior ,oblique ,muscle and its ,pulley #aag ,other ,extrinsic ,muscles1 ,the #aah ,three ,tunics of the ,eye1 the ,hyaloid and its ,attachments1 ,the #abj ,,illustrations ,,page #j4 ,brain showing eyes with muscles removed1 optic nerves1 and chiasm ,frontispiece #a4 ,glassware and tools #bb #b4 ,the first cut #bh #c4 ,how the point of the scissors is kept away from the underlying tissues #bi #d4 ,half of the sclerotic separated #cj #e4 ,picking up the choroid #ca #f4 ,emptying the eye of its contents #cb #g4 ,isolated hyaloid1 contents and attachments intact #cc #h4 ,petit's ,canal #cf #i4 ,cutting eye into anterior and posterior sections with safety-razor blade #ci #aj4 ,posterior half showing retinal vessels and choroid #dj #aa4 ,showing network of vitreous #db #ab4 ,tearing retina away from posterior half of eye #dd #ac4 ,posterior half of eye with retina removed #de #ad4 ,excavated posterior half of eye #df #ae4 ,split optic nerve #dg #af4 ,ciliary processes and the lens #dh #ag4 ,how to pull off vitreous #ej #ah4 ,processus ,zonuloe #ed #ai4 ,onion-like layers of lens removed #ef #bj4 ,cross section of lens #eg #ba4 ,lenses showing the results of different kinds of treatment #fj #bb4 ,puncturing the cornea #fc #bc4 ,removing the cornea #fd #bd4 ,how to separate the choroid from the sclerotic #fe #be4 ,cutting away the separated sclerotic #fg #bf4 ,scraping the choroid free from the sclerotic #fh #bg4 ,the isolated choroid #fi #bh4 ,inserting scalpel to loosen lens and cut through vitreous #gj #bi4 ,taking out lens and 8core0 of vitreous #ga #cj4 ,squeezing out remaining part of vitreous #gb #ca4 ,cutting through the iris #ge #cb4 ,cutting around the ciliary ring #gf #cc4 ,lens1 iris1 and part of vitreous removed #gg #cd4 ,how to force blowpipe into the vitreous #gh #ce4 ,bulging out of vitreous caused by blowing air through glass blowpipe #gi #cf4 ,showing vitreous removed #hj #cg4 ,folding the retina by blowing air at it through blowpipe #ha #ch4 ,suspended retina4 ,sclerotic ready to be cut away #hb #ci4 ,showing sclerotic nearly all cut away #hc #dj4 ,isolated retina #hd #da4 ,the beginning of the cutting of the eye for sagittal sections #hg #db4 ,method of cutting through the crystalline lens #hh #dc4 ,cutting through cornea to complete the sagittal sections #hi #dd4 ,sagittal section enlarged #ij #de4 ,part of calf's head showing knitting needles inserted in puncta #ic #df4 ,course of knitting needles showing the course of the canaliculi #id #dg4 ,initial cuts to be made in the skin #ih #dh4 ,first cut in bones of orbit #ii #di4 ,all the cuts to be made in bones of orbit #ajj #ej4 ,how to pry bone loose #aja #ea4 ,dissecting close to bones of orbit #ajb #eb4 ,excavated orbit #ajc #ec4 ,anterior view of enucleated eye #ajd #ed4 ,side view of enucleated eye4 ,all parts in situ #ajd #ee4 ,enlarging pupil for ophthalmoscopic inspection #ajg #ef4 ,how to get rid of the pucker in the cornea #ajh #eg4 ,window cut in the eye #aaj #eh4 ,pins inserted in lacrimal ducts #aab #ei4 ,capsule of ,tenon blown up #aae #fj4 ,showing the extrinsic muscles of the eye #aah #fa4 ,cutting through the iris #abj #fb4 ,scraping ciliary processes free4 ,choroid cut around ciliary ring #aba #fc4 ,cutting away choroid #abb #fd4 ,three tunics1 hyaloid1 and lens #abc ,,preface ,the aim of this booklet is to present to the eye-specialist1 the teacher1 the student1 and others interested in the study of the anatomy and physiology of the eye1 some definite methods to follow in the dissection of that organ4 ,most dissections of the eye are not made with the same degree of care and skill used in the dissections of other organs4 ,in following the usual method of dissecting eyes1 much of the important detail is lost4 ,often certain membranes are confounded with others1 and wrongly demonstrated4 ,furthermore1 an eye is merely divided by some demonstrators into an anterior and a posterior half1 a very short time is spent by the students scrutinizing each half2 then the text-book is turned to1 and the anatomy is studied descriptively4 ,not enough time has been given to thoroughly dissecting all parts of the eye4 ,as much time should be given as is necessary to bring out prominently all its parts4 ,other organs of the body are more thoroughly dissected1 and1 therefore1 the student has better opportunity to gain a clearer comprehension and better understanding of the anatomy and physiology of those organs4 ,also1 as much time should be given1 proportionately1 to the learning of the technique of the dissection of the eye as is given to the learning of the technique of dissecting other organs of the body4 ,many now make a direct specialty of ministering to those suffering from errors of ocular refraction1 ocular diseases1 and ocular reflexes1 and for those specialists1 principally1 this book is written4 ,it is to fulfil its mission to them by acting as a guide and as a complement to the descriptive matter in the text-book4 ,it is sent forth in the hope that it will tend to create more interest in the study of the practical anatomy of the eye4 ,it is written with a desire to stimulate the ability to make careful and intelligent observation4 ,it carries with it1 as a final end1 an earnest wish that it may1 in some small way1 be the means of opening up to the original researcher1 a larger field for the further study of the most important of the senses--the eyesight4 ,most of the dissections explained in the following pages are original2 some1 however1 are only revisions of old methods4 ,this opportunity is taken to acknowledge the many helpful suggestions that were made by ,dr4 ,ivin ,sickels1 of the ,college of the ,city of ,new ,york1 and by the late ,dr4 ,edward ,c4 ,spitzka1 of ,new ,york4 ,thanks are due ,mr4 ,e4 ,f4 ,howes1 of ,messrs4 ,swift ,co41 for furnishing the necessary supply of beef eyes2 to ,messrs4 ,lee ,beach1 photographers1 of ,new ,york1 for their painstaking efforts in producing good photographs of the actual dissections2 and to ,schlueter ,printing ,company1 of ,new ,york1 for their many courtesies and interest in the production of the book4 ,,frederic ,a4 ,,woll4 ,new ,york1 ,july #ba1 #aiad4 ,,introduction ,in eye dissections it is unnecessary to have either a large equipment of instruments or a special room4 ,to have a laboratory at one's disposal is but a small added convenience4 ,not to have it1 is no serious hindrance4 ,the work may be carried on and successfully done in one's office or in the home1 as well as in class-room or laboratory4 ,if it is true that the atmosphere of a laboratory adds zeal to the efforts of a worker1 but there is no laboratory available1 then reverse the order2 let the zeal of the worker add to the atmosphere of the place in which he is doing his work4 ,two things1 among others to be mentioned later1 are essential2 a table of convenient height1 and a good light1 natural or artificial4 ,both are but modest needs4 ,compared with other dissections1 there will be found an absence of offensive odors4 ,neither are there any repulsive sensations experienced4 ,such experiences are quite common when making other kinds of dissections4 ,this work is clean and attractive4 ,indeed1 one may even develop a rather keen sense of the sthetic4 ,many of the various parts of the eye1 when separated and properly preserved1 then viewed and inspected1 are bound to bring forth exclamations of appreciation and wonderment4 ,one can then better understand the statement3 8,when ,nature perfected the first eye she took a day off so she could admire the result of her finest piece of handiwork40 ,this does not imply that dissections of the eye tend to develop art appreciation4 ,appreciation of the wonderful in ,nature's construction of the special organs is not1 however1 to be relegated to a distant point4 ,such appreciation is concomitant with the knowledge that comes from having seen1 handled1 and examined the object studied4 ,the orchestra leader must have a good listening and hearing ear4 ,this is developed in him because he has to exercise constantly his power of listening and hearing4 ,the dissector who would become proficient in eye dissections and in anatomical investigations must have a good seeing eye and a dextrous hand4 ,to acquire these two most valuable aids necessary to carry on careful inquiry or research1 it is essential to practise using the eye and the hand4 ,combined with the expertness of these two1 must be the ability to continue one's efforts in the face of failure2 to redouble one's efforts to attain success despite the shortcomings of eye or hand4 ,this simply means practise and patience4 ,and the one who is without that wonderful virtue1 patience1 will never stay long enough with his problem to gain either an observing eye or an expert hand1 or to achieve his end1 and thereby reap the full and pleasing results of his efforts4 ,in order of importance1 patience really precedes dexterity1 skill1 and observation2 and persistence of effort is a factor not to be entirely outshone by any other virtue4 ,with these attributes1 knowledge of the subject in hand naturally follows4 ,one reason why eye dissections are easily carried on is because material can always be readily procured4 ,any butcher will furnish sheep1 pig1 or beef eyes4 ,or1 if one has the time to visit the manager of a slaughter-house1 and make known to him one's needs1 he will supply enough eyes to carry through a host of interesting dissections and experiments1 and give sufficient material for careful1 orderly1 and fruitful study4 ,perhaps in no other kinds of dissections will the investigator find so much of interest1 or have his efforts crowned with such abundant and satisfactory results1 as in the dissections of the eye4 ,but no one should try to study all parts of the eye with only one specimen4 ,to try to do so is an error1 and a common one often committed by both teachers and students4 ,specimens cost little or nothing1 and it is no more trouble to prepare a half-dozen eyes for dissection than one4 ,the cost of preparation1 too1 is but little more for a number of eyes than it is for one1 and may be no more in some instances4 ,besides1 having enough material on hand saves time in case of a failure4 ,also1 one can quickly repeat a dissection1 and so procure any number of desired specimens of specific parts1 or do over again the same dissection on another eye just for the purpose of practise1 and thus add to one's dexterity4 ,it is1 therefore1 strongly advocated to have plenty of material on hand before beginning work4 ,economy here is not even 8penny wise40 ,the tools1 or instruments1 needed are but few in number2 an ordinary scalpel1 a pair of blunt tweezers1 or forceps1 as they are sometimes called2 a pair of sharp-pointed tweezers1 a pair of small1 sharp-pointed scissors of about three to three and a half inches in length1 and a pair of large scissors1 about four or five inches in length1 having one jaw sharp-pointed and one jaw blunt4 ,for glassware1 any wide-mouthed jar or bottle1 such as the ordinary fruit or jelly jar1 will do for preparing material4 ,for clarifying tissues1 or for preserving and keeping them1 small1 wide-mouthed bottles or vials should be used4 ,and for temporary keeping1 or for purposes of 8running through0 various fluids1 the regular ,stender dishes are most convenient4 ,a glass graduate is almost indispensable if accuracy in measuring fluids is desired4 7,fig4 #a47 ,illustration3 ,fig4 #a4 ,the chemicals needed are few in number and small in quantity3 ,alcohols in varying strength1 which can be made by diluting a #ie per cent4 alcohol1 and keeping an absolute alcohol on hand4 ,a few ounces of formaldehyde will make enough solutions of different strengths to be sufficient for the preparation and keeping of many specimens4 ,of other chemicals1 such as xylol and cedar oil1 only small quantities are needed2 enough to cover a specimen4 ,fifteen to twenty cents worth of each will be an ample supply to keep on hand4 ,all of these may be procured at any large drug store1 and are the only chemicals required for doing the dissections as explained in this book4 ,before further advance is made1 it will be best to state that this work deals only with methods for dissecting the various parts of an eye1 and is primarily intended to aid in the study of the anatomy and physiology of the eye by being used in conjunction with such books as 8,gray's ,anatomy10 8,a ,text-,book of ,physiology10 by ,howell1 8,the ,anatomy and the ,physiology of the ,eye10 by ,brown and ,zoethout1 and similar other works of authority4 ,however1 if it is desired to acquire only specimens1 then1 of course1 no other works are necessary1 and the matter contained herein is sufficient to enable one to procure just what is wanted4 ,it is also wise to state here that since human eyes are hard to procure1 and not available in large quantities1 one must resort to the use of the eyes of animals1 which are procurable in large quantities1 and which may be used without 8feelings0 in the matter4 ,though there is a difference between the eyes of human beings and the eyes of other animals1 the difference is slight and of minor importance when compared with the similarity of the more important parts4 ,,technique ,,of ,,eye ,,dissections ,,removal ,,of ,,the ,,hyaloid ,,membrane ,,with ,,contents ,,and ,,attachments ,,intact#ab ,one of the easiest and most satisfactory dissections to attempt is the isolating of the hyaloid membrane with its contents and its attachments4 ,the success one meets with in making this dissection will surely prove a strong incentive for making all the rest4 ,for these reasons this has been placed first in this arrangement4 ,in eye dissections it is quite customary1 in giving directions for dissections1 merely to mention the hyaloid membrane and its relations with other parts of the eye4 ,rarely is there any attempt made to isolate it4 ,often1 too1 the retina is mistaken for the hyaloid1 and the retina then wrongly demonstrated as being attached to the choroid4 ,of course1 it is impossible to separate the hyaloid from the vitreous2 but a dissection can be made which1 when placed in a glass of some kind1 will show the hyaloid4 ,if the following simple technique is carefully observed1 the membrane1 with all its connections1 can be easily separated from certain other parts of the eye4 ,opportunity for thorough study and observation will then be made extremely easy4 ,procure the eye of either a sheep or a bullock4 ,instead of following the usual procedure of hardening in any one of the several solutions used for the purpose of toughening the ocular tissues1 place the eye in a cool place and permit it to collapse a trifle4 ,usually two or three days is a sufficient length of time to accomplish the result4 ,experiments have shown that if an eye is too fresh the ciliary processes will not be easily detached from the hyaloid 7zonular processes71 and if the eye has been in a preserving fluid1 the same result will follow4 ,a sheep's eye will make a better specimen even if it is small1 because the ciliary processes are more easily separated from the zonular processes4 ,if a bullock's eye is used1 it must be left in a cool place a day or two longer than in the case of a sheep's eye1 in order to permit a long enough time to elapse to allow disintegration of the eye to take place sufficient to have the two processes separate easily and cleanly4 ,illustration3 ,fig4 #b--,making the first cut4 7,page #bg47 ,illustration3 ,fig4 #c--,showing how the point of the lower jaw of the scissors is to be kept away from the underlying tissues4 7,page #bg47 ,illustration3 ,fig4 #d--,showing about half of the sclerotic separated4 7,page #bi47 ,with a pair of dissecting forceps pinch up the sclerotic about #e mm4 anterior to the equator4 ,with a pair of small1 fine-pointed scissors1 make an incision4 7,fig4 #b47 ,next hold the eye in the left hand without exerting any pressure4 ,insert the point of the scissors into the incision which has been made1 and cut4 ,be careful to keep the point of the scissors close to the sclerotic or an untimely puncturing of the choroid will occur4 7,fig4 #c47 ,continue the cutting on a line parallel to the equatorial meridian and about #e mm4 anterior to it until about half the sclerotic has been separated4 ,in cutting1 always move the point of the scissors forward with a slight oscillating lateral movement4 7,fig4 #d47 ,while doing this1 partly suspend the eyeball from the point of the scissors4 ,doing these things will tend to loosen the choroid from the sclerotic and prevent puncturing too soon the former mentioned membrane4 ,now apply pressure in such a manner that the lips of the cut sclerotic will gap4 ,into this put the point of the scissors and very carefully pick up the choroid and the retina with the point of the scissors and cut them4 7,fig4 #e47 ,if the choroid alone has been picked up and separated1 the retina will show milky white or yellowish white underneath4 ,the retina must then also be separated4 ,care must be taken not to go deeper than the retina or the hyaloid may be damaged4 ,continue the cutting of the choroid and the retina for a distance of about #bj mm4 ,apply enough pressure occasionally so that the vitreous will be forced upward and above the cut choroid and the retina4 ,this will show whether any strands of the two membranes have been left uncut4 ,if the separation is complete for the distance specified above1 invert the eyeball1 squeeze and shake gently over some receptacle1 such as a ,stender dish1 three-fourths filled with a #b or #e per cent4 solution of formaldehyde1 and the hyaloid membrane containing the vitreous1 its attachments1 suspensory ligament to the lens capsule1 and lens1 will drop out intact1 as when one empties the contents of an egg4 7,fig4 #f47 ,illustration3 ,fig4 #e4--,picking up the choroid with the point of the scissors4 ,illustration3 ,fig4 #f--;,a4 ,hyaloid1 vitreous1 and lens ready to drop out of the eyeball4 ,illustration3 ,fig4 #g--,photograph of dissected hyaloid membrane 7,a71 with pigmented indentations of the ciliary processes1 the suspensory ligament 7,b71 and the crystalline lens in its capsule 7,c74 7,page #cd47 ,many times a considerable amount of pigment from the second tunic will remain attached to the processus zonuloe4 ,this pigment may be easily removed by scraping it off with the sharp edge of the scalpel or by brushing it off with a soft1 wet tooth-brush4 ,it is unwise to use alcohol as a preservative because it produces an almost immediate opaqueness and hardness which spoils the specimen for further study4 ,this description may give the impression that the dissection is a lengthy one2 however1 it can be done by an expert in two or three minutes2 by a beginner in five or six minutes4 ,for purposes of demonstration or study the specimen should be placed in a small bottle or a vial containing a #e per cent4 solution of formaldehyde4 ,it can then be examined with hand lens or microscope4 7,fig4 #g47 #a ,approved as an original article in ,the ,anatomical ,record1 ,september1 #aiab4 #b ,this dissection1 and several of the following1 appeared in ,the ,optical ,journal and ,review1 beginning with the issue of ,january #af1 #aiac4 ,,the ,,canal ,,of ,,petit ,the canal of ,petit is a 8triangular space around the circumference of the lens40 ,that it can be 8inflated through a fine blowpipe inserted through the suspensory ligament10 is the usual direction given4 ,however1 the ordinary 8fine blowpipe0 is much too large and too dull to be inserted through the suspensory ligament4 ,take a long medicine-dropper 7#e or #aj cents at a drug store71 or a pipette1 and heat it until it is red hot over an alcohol lamp or a ,bunsen burner2 hold one end with one hand and the other end with a pair of tweezers4 ,as the glass becomes white hot pull the tube apart4 ,this will leave the places of separation pointed and sharp-edged4 ,use the larger of the two pieces4 ,sometimes the point or tapering end of the tube is too long and the bore too small4 ,all that is necessary is to first mark off with a file the length to be broken off1 and then that length may be snapped off1 leaving a sharp-edged1 tapering point4 ,illustration3 ,fig4 #h--;,a4 ,glass blowpipe4 ,b4 ,petit's canal4 ,after having completed the first dissection 7the hyaloid1 contents and attachments71 and the specimen has been in the formaldehyde solution for ten days or two weeks1 it will have become hard and tough enough to stand a considerable amount of rough handling4 ,if the specimen has been kept in a large receptacle1 such1 for instance1 as a jar1 remove it with a spoon2 if in a small jar or vial1 empty out the fluid1 then slide the specimen out on whatever has been prepared to receive it4 ,turn it so that the lens will be uppermost4 ,find the suspensory ligament in the ,zone of ,zinn4 ,insert the pointed end of the glass tube1 close to the lens1 and blow gently until the canal shows its sacculated construction by filling with air1 giving the appearance of a lot of little bubbles surrounding the periphery of the lens4 7,fig4 #h47 ,it may be necessary to move the blowpipe in and out in order to find the canal1 all the while blowing steadily through the tube4 ,,the ,,interior ,,of ,,the ,,eye ,for the study of the interior of the eye and its contents in situ either a fresh or a hardened eye will do2 a hardened eye is preferable4 ,in the dissection for isolating the hyaloid membrane1 vitreous1 lens1 and other parts1 the anterior and posterior halves of the evacuated eye may be separated entirely1 and each half studied4 ,however1 the choroid and the retina will be more or less mutilated1 and the vitreous and other parts will be removed4 ,the absence of these parts will prevent one from receiving a definite idea of their anatomical relationships4 ,therefore1 it is better to work with an entire and complete eye4 ,illustration3 ,fig4 #i--,showing method of cutting eye into anterior and posterior sections with safety-razor blade4 ,remove all the muscles and fatty tissues from the outside of the globe2 then cut it in half through the equator1 thus dividing it into an anterior and a posterior half4 ,the cutting of the sclerotic1 as well as the underlying tissues and the vitreous1 should be done with the large scissors2 using a knife or scalpel will tend to disturb the positions of those tissues or so tear them that they will not be of much use for purposes of study4 ,an ordinary safety-razor blade makes an excellent instrument for separating the eye into two halves1 because it cuts through the tissues without tearing them in any way4 7,fig4 #i47 ,the rather dark colored1 viscid fluid that escapes when the eye is halved is the perichoroidal lymph1 not the aqueous1 as is sometimes stated4 ,,the ,,posterior ,,half ,the posterior half is taken first because it is the simplest and easiest of the two halves to dissect4 ,in this half of the eye the retina may be readily seen through the vitreous2 the choroid and its apparent iridescent colors through both vitreous and retina4 7,fig4 #aj47 ,remove the vitreous by simply tilting this half of the eye1 and with the finger push out the vitreous4 ,illustration3 ,fig4 #aj--,the retina1 retinal vessels1 and iridescent choroid showing through the vitreous4 ,sometimes the vitreous will adhere very closely to the retina4 ,this occurs especially when the eye has been in formaldehyde for a long time4 ,in such a case the removal of the vitreous without injuring the retina requires patience and care4 ,the use of the scalpel and the scissors may become necessary4 ,another very good way to remove the vitreous is to take hold of the sclerotic1 turn it so that the vitreous is downward1 and then shake gently until the vitreous separates itself from the retina and1 drops out4 ,after the vitreous has been removed1 notice its glassy appearance2 hence its name--hyaloid body4 ,try to pull it apart with the fingers1 and it will be noticed that it seems to be held together by more or less of a network of fibres4 7,fig4 #aa47 ,illustration3 ,fig4 #aa--,showing how vitreous seems to be held together by a network of fibres4 7,page #da47 ,whichever method for removing the vitreous is followed1 the retina will be left rather badly wrinkled and out of place4 ,if the last-mentioned method1 which is really the best of the three described1 is the one adopted1 the retina will be left in an entirely collapsed and folded form4 ,in any case1 to straighten out the retina against the choroid1 immerse the whole posterior half in water1 inside uppermost4 ,the retina will then slowly unfold itself and lie flat against the choroid4 ,with the tweezers remove the whole half from the water2 tilting it slowly to empty it of all the water1 and1 having done so1 turn it down upon the table rather forcibly in order to help it drain itself of all the water4 ,notice the thinness of the retina1 and1 also1 that the seeming iridescence of the choroid shows through4 ,the optic disc1 which is the point of entrance of the optic nerve1 and the optic cup are easily recognized1 though neither will be seen as large as when viewed in the living eye with an ophthalmoscope4 ,the blood vessels of the retina1 as they ramify outward or forward1 after their entrance through the optic nerve through which they pass1 are also very plainly seen4 ,a closer inspection will show1 in the very centre of the 8entrance0 of the optic nerve1 a whitish1 pointed vessel1 about #a or #b mm4 long4 ,that is the sloughed-off and atrophied end of the hyaloid artery1 which1 when the eye was in an embryonic state1 ran forward from the central artery of the retina through the hyaloid canal to the posterior surface of the lens4 ,with the forceps pick up the peripheral edge of the retina1 and1 by pulling gently upward1 tear it away from its apparent place of attachment to the 8entrance0 of the optic nerve4 7,fig4 #ab47 ,when this has been done1 there will be seen some threads protruding from the optic nerve4 ,filling the half with water will tend to separate these strands1 which are optic-nerve elements4 ,illustration3 ,fig4 #ab--,picking up the retina in order to tear it away from the entrance of the optic nerve4 ,illustration3 ,fig4 #ac--,the lighter area is the field of iridescence of the choroid4 ,after the removal of the retina1 the iridescence of the choroid 7tapetum lucidum7 7,fig4 #ac7 may be examined with a hand lens1 or1 after its removal1 a piece may be cut and placed under a microscope4 ,this iridescence is1 of course1 not present in the human eye4 78,physiology of the ,senses10 ,mc,kendrick ,snodgrass1 page #aja47 ,illustration3 ,fig4 #ad--;,excavated posterior half of the sclerotic4 ,after the choroid is removed1 which is accomplished in the same manner that the retina is removed1 the inner side of the sclerotic is laid bare to view4 ,the brownish color is mostly due to the presence of a small amount of pigment in the cells of one of the inner layers1 it is also due1 to a slight extent1 to the staining influence of the perichoroidal fluid4 7,fig4 #ad47 ,,the ,,optic ,,nerve ,illustration3 ,fig4 #ae--;,enlarged to show the entrance of the optic nerve4 7,page #dh47 ,the excavated posterior half may be used now to show and to study the construction of the optic nerve4 ,in cutting the optic nerve away from the sclerotic leave at least #e mm4 of the sclerotic attached4 ,it will make handling easier4 ,with the thumb and forefinger of the left hand hold the nerve in such a way on the table that it will be straightened out lengthwise1 and then1 using the scalpel or a safety-razor blade1 the latter being preferable1 cut the nerve in two longitudinally4 7,fig4 #ae47 ,the cutting must be done with one movement1 otherwise the nerve will be hacked1 and will not make a good specimen4 ,this specimen will show the way the nerve fibers are arranged4 ,a cross section should be cut from the optic nerve of another eye1 and then the two sections should be compared4 ,the cross section will show the sheath of the nerve a little better than will the longitudinal section4 ,illustration3 ,fig4 #af--,showing ciliary processes and crystalline lens4 ,in cutting the longitudinal section1 one is sometimes so fortunate as to cut through the central blood vessels of the retina4 ,these vessels will show up then as a rather thin dark streak about #e or #f mm4 long4 ,,the ,,anterior ,,half ,the anterior half will show the lens in situ1 the ciliary processes1 the posterior aspects of the iris and the lens1 the corona ciliaris1 the orbicularis ciliaris1 and the ora serrata4 7,fig4 #af47 ,if the eye has been cut in two too far forward of its equator1 the ora serrata will not be present4 ,the ciliary processes and posterior aspect of the lens may be seen to better advantage when the anterior half of the vitreous is removed4 ,this is done with the dull-pointed tweezers1 by catching hold of the vitreous at any part of its free or cut margin1 and stripping it off both the ciliary processes and the lens1 using a prying1 pulling movement to do so4 7,fig4 #ag47 ,the two layers of the pigment cells1 pars ciliaris retinae1 which cover the inner surface of the processes1 may be removed by picking them away carefully with the tweezers4 ,the processes then will be seen to be a whitish color4 ,the pupillary edge of the iris rests upon the capsule of the lens1 but the nearer the approach is to the choroidal edge the farther the iris is from the lens2 thus are formed the anterior and the posterior chambers of the eye4 ,the dissection of the sagittal section of the eye1 explained further on1 will show these two chambers in section4 ,one will gain a much clearer conception of their construction in that section than in the 8anterior half0 specimen4 ,illustration3 ,fig4 #ag--;,anterior half1 showing how to pull off vitreous4 7,page #di47 ,now1 remove the lens1 using the point of the scalpel to cut through the suspensory ligament close to the lens4 ,when this has been done there will be seen in the anterior chamber a thin1 watery liquid--the aqueous humor4 ,the corona ciliaris and orbicularis ciliaris may be better seen and studied if viewed through a hand lens4 ,,the ,,iris ,to see the iris1 take hold of the cut edge of the choroid1 and1 gently pulling1 separate it from its attachment to the corneo-scleral junction4 ,the white ring on the anterior surface of this part of the second coat of the eye is the ciliary ring4 ,with a scissors1 cut around this ciliary ring at its outer edge4 ,this specimen will show the anterior surface of the iris1 and on the posterior side it will show the close relationship between the iris and the ciliary processes4 ,a hand lens will help greatly to bring out the very interesting fine points4 ,,the ,,cornea ,after the anterior portion has had everything removed from it there will be left nothing but the first coat or tunic of the eye--the anterior portion of the sclerotic and the cornea4 ,the way the cornea seems to fit into the sclerotic is not quite as one is led to believe when told that it fits into the sclerotic much the same way in which a watch crystal fits into a watch4#c ,holding this part of the eye up to a strong light one will see that the sclerotic seems to overlap the cornea in the vertical axis4 ,by using the tweezers the cornea may be split4 ,nothing in the way of locating its layers can be recognized1 however1 unless a section is made for microscopic examination4 ,the epithelial may be scraped off when the cornea is a trifle dry4 ,this is the ocular epithelium reduced to a layer of flattened cells4 ,,the ,,crystalline ,,lens ,if the preceding dissections have been done1 the crystalline lens will already have received some notice4 ,to study the lens properly one should use an eye that has not been hardened and also an eye or the lens of an eye that has been in a #e per cent4 solution of formaldehyde for about two weeks4 ,the lens in the unhardened eye will prove too friable to permit much handling4 ,the dissection should be made1 however1 in order to give opportunity to notice the crystalline clearness of the lens substance1 its great magnifying power1 its attachments1 its capsule1 etc4 ,for this purpose it is necessary to proceed only as in the dissection for the 8hyaloid membrane1 etc40 ,that is1 use an eye that has been kept in a cool place for several days1 and then open it1 and remove hyaloid1 vitreous1 and lens intact1 as in the first dissection taken up in this book4 ,to examine the specimen in detail1 turn it so the lens will be uppermost4 7,fig4 #ah47 ,to remove the lens it is necessary to separate the suspensory ligament1 using for this purpose the small-pointed scissors4 ,the capsule may be removed by picking it up on the periphery of the lens1 and stripping it off4 ,it will peel off about the same way that the outer skin of a bean or pea does4 ,illustration3 ,fig4 #ah--;,enlarged to show the processus zonuloe4 7,page #ec47 ,the tri-radiate lines on the posterior and the anterior surfaces of the lens will not be as clearly discernible as in the lens coming from the hardened eye4 ,close inspection and the use of a hand lens will help bring them out more clearly4 ,now1 with the point of the scalpel try to separate the outer layers 7cortex7 from the harder inner layers 7nucleus74 ,this will not prove very successful but is suggested for the purpose of comparison when the same thing is done to the hardened lens4 ,it will be found that the lens after having been in the formaldehyde solution is no longer crystal like1 but more or less translucent4 ,when viewed from either the anterior side or the posterior side1 the tri-radiate lines on each surface will be seen to begin at the poles of the lens and radiate outward toward the lens equator4 ,holding the lens up to a strong light will show that though the lines on either surface form angles of #abj degrees1 the angles formed by the lines on one side with the lines on the other side are #fj degrees4 ,on the anterior surface of the lens the vertical line extends upward from the pole2 on the posterior surface downward from the pole4 ,to study the laminated structure of the lens1 it is best to boil the lens4 ,the best way to do that is to drop the lens from either a hardened or unhardened eye into boiling water4 ,let it boil in the water for about two and a half to three minutes4 ,longer than that time will cause the lens to be put out of shape1 and make it so fragile that it can no longer be handled without having it fall apart4 ,if the lens comes from an unhardened eye it might be best to boil it not more than about two minutes4 ,illustration3 ,fig4 #ai--,showing the way the onion-like layers of the lens may be peeled off4 ,insert the point of the scalpel carefully at one of the poles1 and lift gently in the direction of one of the radiating lines4 ,this will tend to raise one of the concentric layers1 which can be easily peeled off4 ,repeat this in the direction of the other two radiating lines4 ,examining1 with a hand lens1 the exposed surfaces and the layers1 as they are taken off1 will show the arrangement of the lens fibres1 and will also show plainly their directions4 7,fig4 #ai47 ,to get another view of the onion-like layers of the lens1 cut through it with a safety-razor blade1 either longitudinally or equatorially4 7,fig4 #bj47 ,the better way is to have enough lenses to make one of each kind4 ,never try to work with only one piece of material4 ,if the lens is first stained with chromic acid the layers may be seen better1 or1 a simpler way is to drop the lens1 before cutting it in two1 into a carmine solution2 red ink slightly diluted1 will do4 ,illustration3 ,fig4 #bj--,section through lens showing its concentric layers4 ,a lens that has been boiled and partly dissected may be placed in a #e per cent4 formaldehyde solution1 and kept indefinitely4 ,the lens fibres1 concentric layers1 and lens laminae in such a specimen will always be interesting4 ,a lens that has lost its transparency because of hardening in formaldehyde or boiling may be made clear and nearly transparent again in the following way3 ,first3 ,place the lens in a #ej per cent4 alcohol for several hours4 ,second3 ,remove the lens1 and let it drain on a piece of blotting-paper2 then place it in a #ge per cent4 alcohol4 ,third3 ,remove the lens1 as before1 then place it in an #he per cent4 alcohol4 ,the lens may be left in this alcohol from ten to twelve hours1 after which length of time it should be removed and drained4 ,fourth3 ,place the lens in an absolute alcohol1 and leave it there for ten or twelve hours4 ,several hours longer will not injure the lens1 nor interfere with the success of the work4 ,fifth3 ,remove the lens from the absolute alcohol4 ,place it upon a piece of blotting-paper1 moving it to another place on the blotting-paper whenever the paper around the lens seems to have taken up as much moisture as it can hold4 ,be sure that the lens has given up nearly all1 if not all1 moisture4 8,running through the alcohols10 as this process is called1 is for the purpose of dehydrating the tissue4 ,it will be on the side of safety to let the lens lie exposed on the blotting-paper for an hour4 ,sometimes1 if the capsule has not been removed1 a small quantity of alcohol will remain between the lens and the inner surface of the capsule4 ,this must be removed4 ,it may be done by either puncturing the capsule with a pin or needle1 and squeezing out the fluid1 or by removing the capsule entirely4 ,the latter is preferable4 ,now drop the lens into xylol4 ,benzine will answer1 though it will not produce quite so clear a lens as the xylol does4 ,at the end of #bd or #cf hours the softer cortex will show quite clear1 while the harder nucleus will be still cloudy4 ,at the end of a week the whole lens1 if it is a small one--pig1 calf1 sheep--will have become quite clear and transparent2 if from a beef eye it will take longer4 ,it sometimes takes nearly two weeks4 ,in the case of a boiled lens it will take much longer to clear2 it may take a month4 ,cedar oil may also be used for the purpose of clarifying or 8clearing0 the lens4 ,harden in the usual way1 run through the alcohols1 and then place in cedar oil4 ,the oil1 however1 will stain the lens a yellowish brown1 and the lens will not be as transparent and clear as when xylol is used4 ,illustration3 ,fig4 #ba4 ,a4 ,lens hardened in formaldehyde4 ,b4 ,lens hardened in formaldehyde1 run through the alcohols1 and cleared in xylol4 ,c4 ,lens hardened in formaldehyde1 run through the alcohols1 and cleared in cedar oil4 ,d4 ,boiled lens4 ,the longer a lens is left in either of these two clarifying fluids the harder and smaller it will become4 ,at the end of a month or six weeks the lens will have become so hard that it can no longer be cut through with a knife4 ,if it is desired to halve it1 a scroll saw will be found to be the best thing to use for this purpose4 7,fig4 #ba47 #c 8,anatomy and ,physiology of the ,eye10 ,brown ,zoethout4 ,,the ,,choroid ,select an eye that has had a long part of the optic nerve left on it and place it into a #e per cent4 solution of formaldehyde4 ,leave it in that solution for from two to three weeks4 ,that period of time in the fluid will be sufficient to permit the choroid to become sufficiently toughened and hardened4 ,leaving it in the solution longer than that length of time will not injure the eye in any way4 ,illustration3 ,fig4 #bb--,showing how to puncture the cornea4 7,page #fb47 ,illustration3 ,fig4 #bc--,removing the cornea4 7,page #fc47 ,illustration3 ,fig4 #bd--,showing method of inserting the scalpel to separate the choroid from the sclerotic4 ,after having removed the eye from the formaldehyde1 wash it for a few moments in running water4 ,this will remove the preserving and hardening fluid from the surface1 and will save the hands a little from the effects of the fluid4 ,next remove all the muscles and fatty tissues from the sclerotic4 ,after that has been done1 puncture the cornea with the pointed jaw of the scissors about #b mm4 from the corneo-scleral junction4 7,fig4 #bb47 ,then proceed to cut the cornea away1 being careful not to lacerate the choroid or the iris4 7,fig4 #bc47 ,the escaping aqueous humor will flow over the eye and make it very slippery1 and1 therefore1 difficult to hold4 ,dip the eye in water1 wash it1 and then take it out and thoroughly dry it with a cloth4 ,this procedure is absolutely necessary1 and1 if omitted1 will surely result in the dropping of the eye about the time the work on the specimen is nearly finished4 ,insert the scalpel between the peripheral edge of the exposed iris and what is left of the cornea4 ,with the back edge of the scalpel1 gently loosen the choroid from the inner side of the corneo-scleral junction to which part it is not securely attached4 7,fig4 #bd47 ,this requires only ordinary care1 and but little skill other than that necessary to always keep the scalpel close to the inner surface of the sclerotic4 ,when the choroid-iris edge has been detached from the inner side of the corneo-scleral junction1 the weight of the contents of the second tunic will cause it to sag and give opportunity to easily separate1 with the back edge of the scalpel1 the choroid from the sclerotic for about a distance of from #h to #aj mm4 ,it has been the method in the past to force water through a blowpipe between the sclerotic and the choroid1 in order to separate the attachments4 ,it has also been the method to work under water when wishing to expose or isolate either the choroid or the retina4 ,it is unnecessary to do either of these two things4 ,when the sclerotic has been loosened from the choroid for about #aj mm4 back from its cut edge around the eye1 carefully cut the loosened part away4 7,fig4 #be47 ,then loosen the choroid as far back as to within #a cm4 of the optic nerve4 ,cut the separated sclerotic away4 ,it will be well to state here that during this dissection the specimen should not be lifted from the table4 ,keep the eye resting on the table all the time1 and never lift it by holding it suspended from the optic nerve4 ,loosening the choroid from the sclerotic up to this point is a very easy matter2 ordinary precaution is all that is necessary to prevent puncturing the choroid with the scalpel1 just be sure to remember to keep the point of the scalpel close to the sclerotic4 ,illustration3 ,fig4 #be--;,cutting away the sclerotic after it has been loosened from the choroid1 as shown in ,fig4 #bd4 ,illustration3 ,fig4 #bf4--,showing how to scrape the choroid free from the sclerotic near the optic nerve4 ,to remove the remaining part of the first coat is a little more difficult1 and needs a little more care4 ,hold the optic nerve in the left hand1 and pull it so that the sclerotic will pull away from the choroid4 ,then1 using the cutting edge of the scalpel1 scrape the choroid loose from the sclerotic close up to the entrance of the optic nerve4 7,fig4 #bf47 ,do not separate the optic nerve from the choroid4 ,cut away the remainder of the sclerotic close up to the optic nerve and the choroid will be free4 7,fig4 #bg47 ,illustration3 ,fig4 #bg--,showing the choroid1 the optic nerve still attached1 the ciliary ring1 and the ciliary nerves4 ,illustration3 ,fig4 #bh--,showing method of inserting scalpel in order to loosen the lens and cut through the vitreous4 ,to get a perfect specimen and completely isolated choroid1 it must be emptied of its contents4 ,insert the scalpel between the lens and the iris1 force it on through1 and in such a manner as to keep the scalpel close to the ciliary processes4 7,fig4 #bh47 ,cut the vitreous around the processes4 ,push the scalpel further into the vitreous1 and cut out the central part of it1 just as one would cut out the core of an apple4 7,fig4 #bi47 ,remove the scalpel1 pick out the lens and the cut centre of the vitreous with the broad-point tweezers1 holding the choroid a trifle suspended by the optic nerve4 ,the remaining part of the vitreous may be broken down by cutting with the scalpel1 and by squeezing and crushing with the fingers of both hands4 7,fig4 #cj47 ,the choroid will be tough enough to stand this treatment provided the pupil is left clear and open to prevent inter-choroidal pressure4 ,after the vitreous has been removed the choroid will be left in a greatly collapsed condition4 ,dropping it into water and letting it fill up will make it resume its original shape immediately4 ,the retina does not always come out with the vitreous4 ,in such a case1 the tweezers may be used to pick out the retina when the choroid is in a collapsed condition4 ,illustration3 ,fig4 #bi--,taking out the lens and 8core0 of the vitreous4 ,illustration3 ,fig4 #cj--,showing how to squeeze out the remaining part of the vitreous 7,a7 from the choroid4 7,page #ga47 ,this specimen will show the vena vorticosa1 the ciliary nerves1 and their way of ramifying1 and the long ciliary arteries1 which run opposite each other and which may be recognized by their rather colorless1 tubular appearance4 ,the evacuated choroid makes an excellent specimen and one easily examined4 ,place it in a #c per cent4 solution of formaldehyde1 and then examine with a skiascope1 an ophthalmoscope1 or by 8oblique illumination40 ,this dissection is wholly original1 and may be done in about five minutes4 ,the old technique for doing it required at least an hour of time with the possibility of procuring one perfect specimen in every six or seven4 ,the technique as given here will make it possible to do the work in not longer than five or six minutes for the beginner1 and about four minutes for the expert4 ,,the ,,retina ,isolating the retina from the other tissues requires considerable patience and dexterity4 ,when the retina has been removed and placed in a special receptacle1 it will be found that the specimen is well worth the little amount of time spent in making it4 ,previous techniques1 even the writer's own1 sometimes took nearly two hours to do1 and rarely was the retina isolated without puncturing or tearing it2 perfect specimens were almost impossible4 ,the following method will assure one of success in nearly every instance4 ,failures are almost impossible4 ,punctures1 perforations1 tears1 etc41 are rare4 ,the beginner should isolate the retina in about six to seven minutes2 the expert in about four and a half to five minutes4 ,select an eye with a long optic nerve1 and prepare it for this dissection by placing it in a #aj per cent4 solution of formaldehyde for about ten to fourteen days1 but no longer4 ,if it is left in the hardening fluid longer than that length of time1 it will interfere with the easy removal of the vitreous4 ,illustration3 ,fig4 #ca--;,cutting through the iris4 7,page #gg47 ,illustration3 ,fig4 #cb--,showing how to cut around the ciliary ring4 7,page #gg47 ,the first part of this dissection is the same as the beginning of the dissection for the isolation of the choroid4 ,remove all the outside tissues first1 and then the cornea1 and about #aj mm4 of the sclerotic1 as described in the preceding dissection4 7,see ,figs4 #bb1 #bc1 #bd1 and #be47 ,that will lay bare the iris and a few millimetres of the choroid4 ,illustration3 ,fig4 #cc--,lens1 iris1 and part of vitreous removed4 7,page #gh47 ,after that has been done1 turn the eye so the iris will be uppermost4 ,with the tweezers pick up the pupillary margin of the iris1 and with the fine-pointed scissors cut through the iris and the ciliary processes 7,fig4 #ca72 separate both from the choroid by cutting close to the posterior edge of the processes4 7,fig4 #cb47 ,in doing that1 cut partly through the vitreous also1 but be careful not to injure the peripheral edge of the retina--ora serrata4 ,after the iris has been separated from the choroid1 cut completely through the vitreous in such a way that the lens will also be removed with the iris4 7,fig4 #cc47 ,illustration3 ,fig4 #cd--,showing how to force glass blowpipe 7,a7 into vitreous 7,b74 7,page #hj47 ,illustration3 ,fig4 #ce--,showing bulging out of vitreous caused by blowing air through glass blowpipe4 7,page #hj47 ,illustration3 ,fig4 #cf--,showing the vitreous 7,a7 removed4 ,holding the eye suspended by its optic nerve1 force the glass blowpipe through the vitreous until it all but touches the posterior part of the retina 7,fig4 #cd72 blow gently at first1 increasing the pressure until the vitreous suddenly bulges outward4 7,fig4 #ce47 ,if the iris has been cut away close to the ora serrata1 the vitreous will not only bulge forward1 but it will fall out4 ,if1 however1 it does not detach itself at once1 insert the scalpel close to the choroid and with its flat side press downward until a separation occurs4 ,do not let the vitreous drop out too suddenly1 because it may tear the retina4 ,let the vitreous detach itself slowly by the force of its own weight1 though it will be well to hold some of its weight on the scalpel4 7,fig4 #cf47 ,illustration3 ,fig4 #cg--;,a4 ,showing retina folded upon itself by blowing air at it through the glass blowpipe4 7,page #hc47 ,illustration3 ,fig4 #ch--;,a4 ,showing folded retina suspended from its attachment1 so sclerotic and choroid may be easily cut away4 7,page #hc47 ,after the vitreous has been removed1 turn the eye upward1 and by blowing strongly through the blowpipe at the marginal edge of the retina1 turn the retina upon itself4 ,repeat this until the retina lies in a small wrinkled lump at the 8bottom0 of the posterior part of the eye4 7,fig4 #cg47 ,invert the eye 7,fig4 #ch7 and cut away both the choroid and the sclerotic close to the optic nerve4 ,no care need be taken in doing this until the scissors come close to the optic nerve4 7,fig4 #ci47 ,illustration3 ,fig4 #ci--,showing the sclerotic nearly all cut away4 ,illustration3 ,fig4 #dj--;,isolated retina1 with optic nerve attached4 ,after the choroid and the sclerotic have been cut away1 drop the retina into some water1 and it will slowly unfold itself by 8ballooning0 out into a perfect and beautiful specimen4 7,fig4 #dj47 ,but1 if it is desired to study the specimen closely1 it is better to suspend it in a jar or bottle made of thin glass1 and containing a #e per cent4 solution of formaldehyde4 ,remember that the retina is a delicate membrane in any state2 the slightest rough handling may cause it to be torn1 or otherwise damaged4 ,if the vessel1 in which the specimen has been placed and suspended1 has enough preserving fluid to completely fill it1 and it is firmly stoppered1 the whole thing may be inverted1 and turned in any direction1 even abruptly1 without fear of damaging the retina4 ,this way of keeping the retina will give opportunity to inspect and study the inside as well as the outside of the membrane2 the blood-vessels1 and other important parts easily recognized4 ,,the ,,sagittal ,,or ,,vertical ,,section ,,of ,,the ,,eye ,place an eye in a #e per cent4 solution of formaldehyde for about two weeks4 ,if the eye is kept in that solution longer than that time1 the lens is apt to become so hard that in cutting it the capsule and suspensory ligament will be torn1 and the lens will then become detached2 if for a shorter space of time1 the lens and other tissues will be so soft that all may be so badly torn or lacerated1 that a perfect specimen will not be possible4 ,it sometimes happens that in keeping a number of eyes together in a vessel for the purpose of hardening them in the formaldehyde solution1 the corneas of some will be crushed in4 ,for this dissection1 select an eye that has the cornea in perfect condition4 ,remove all the outside tissues with the scissors1 being particular to have the region immediately surrounding the optic nerve perfectly clear and clean4 ,if the optic nerve is longer than #e mm41 cut it off to that length4 ,illustration3 ,fig4 #da--,showing the beginning of the cutting of the eye for sagittal sections4 ,illustration3 ,fig4 #db--,showing method of cutting through the crystalline lens4 ,to cut the eye in two1 use a safety-razor blade2 never a scalpel4 ,the latter is too thick1 too dull1 and too clumsy a tool4 ,begin by cutting through the optic nerve2 dividing it as nearly as possible into halves4 7,fig4 #da47 ,continue cutting through the sclerotic and all underlying tissues1 stopping at the corneo-scleral junction1 but do not1 during this procedure1 even touch the lens4 ,after the eye has been thus partly separated into1 as nearly as possible1 two equal parts1 lay it down upon the cornea1 and1 holding the razor blade in the forefingers and thumbs of both hands1 cut the lens in two by forcing the blade down through it4 7,fig4 #db47 ,partly open the cut eye to allow one jaw of the large scissors to enter1 turn the eye over so the cornea will rest on that jaw1 and then cut through the cornea4 7,fig4 #dc47 ,illustration3 ,fig4 #dc--,showing method of cutting through the cornea and completing the two sagittal sections4 ,the two specimens may be kept indefinitely by placing them in a #c per cent4 formaldehyde solution4 ,it will be well to remove the lens from one of the specimens1 because it will give better opportunity to see the anatomical relationships4 ,also1 these specimens should be mounted1 one above the other1 between two pieces of glass1 before placing them in the receptacle that is to hold them4 ,much can be studied in such specimens4 ,moreover1 they present to view the various parts of the organ of vision in such an impressive way1 that one does not soon forget the wonderful appearance of the construction of this1 ,nature's perfect camera4 7,fig4 #dd47 ,illustration3 ,fig4 #dd--,sagittal section enlarged4 ,if another eye is cut into two parts1 additional interesting specimens may be procured2 for instance1 one showing the presence of the second coat only1 the retina having been torn out4 ,another good specimen may be made by removing all of the inner tissues1 and leaving only the sclerotic and cornea4 ,this specimen will show that the first coat is almost entirely a coat which affords strength and protection to the parts that lie within4 ,,the ,,papilla1 ,,puncta ,,lacrimalia1 ,,and ,,nasal ,,duct ,the only way to dissect the lacrimal apparatus1 other ocular accessories1 and the extrinsic muscles1 is to procure the head of some animal1 preferably a calf's head1 because of its size4 ,any butcher will supply one for from forty to sixty cents4 ,have the lower jaw removed4 ,it will make a less bulky piece of material to handle4 ,close to the inner canthus1 on the inner side of each lid1 will be found a little rounded eminence--lacrimal papilla--in the centre of which is a small opening--punctum lacrimalis4 ,both may be seen better on the lower lid1 if it is pulled down1 and on the upper lid1 if it is pulled up4 ,illustration3 ,fig4 #de--,showing only a part of a calf's head and the knitting-needles inserted in the puncta4 7,page #id47 ,illustration3 ,fig4 #df4 ,be supplied with two knitting-needles4 ,take one1 lubricate its full length with a little vaseline1 lard1 oil1 or any other lubricant4 ,insert the needle into the punctum of the lower lid1 and push it downward and forward1 aiming to come out in the nose a short distance from its end4 ,at first it may be a little difficult to get the needle started2 if so1 just wiggle the needle1 pushing it at the same time as directed1 until the nasal duct is found4 ,do not remove the needle4 ,to insert the other needle into the punctum of the upper lid is rather difficult2 for that reason the punctum of the lower lid was chosen1 first4 ,grease the needle1 as was done to the first one1 and1 with a little patience and careful manipulation1 the canal opening and its course will soon be found4 ,the needle may then be pushed through until it meets the first one4 7,fig4 #de47 ,from the puncta lacrimalia to the place of meeting of the two needles1 marks the course of the two canaliculi and their junction before they merge and form the nasal duct4 ,leave the needles where they are1 and begin cutting away the skin4 ,the needles will then mark the course of each canal and the duct very plainly4 ,with the small scissors the canals and the duct may be loosened from the surrounding tissues4 ,or1 the scalpel may be used to lay open the canals1 cutting along over the top of the needles4 7,fig4 #df47 ,the cilia1 palpebr1 palpebral conjunctiva1 ocular conjunctiva1 and other superficial ocular accessories may be examined without dissection4 ,,meibomian ,,glands ,,and ,,ducts ,an examination of the eyelids will show the openings of the ducts of the meibomian glands a short distance back of the cilia4 ,very fine pins or needles that have been greased may be easily inserted for a short distance into the ducts1 and then a dissection made along the course of the duct as outlined by the presence of the inserted pins or needles4 ,another way to see the glands is to slice through the ducts1 with the scalpel or safety-razor blade1 the entire width of either eyelid4 ,this will separate the glands into two parts and show their length1 breadth and structure4 ,,enucleation ,,of ,,the ,,orbital ,,contents ,the eyes one procures from a butcher or a slaughter house will always have the extrinsic tissues so badly cut and torn that identification of the various parts and their relations is impossible4 ,therefore1 it is best to supply one's self with the head of an animal1 such as a sheep or a calf1 and dissect an eye with all its extrinsic tissues intact4 ,for this dissection1 a hammer and a chisel are necessary in addition to the tools needed for doing the previous dissections4 ,illustration3 ,fig4 #dg--,showing method of making the initial cuts in the skin4 7,page #ig47 ,illustration3 ,fig4 #dh--,part of calf's head1 showing the first cut to be made in the bones of the orbit4 7,page #ajb47 ,illustration3 ,fig4 #di--,showing all the cuts to be made through the bones of the orbit4 7,page #ajb47 ,using the left orbit1 begin the dissection by making an incision directly over the supra-orbital ridge1 extending from over the inner to the outer canthus4 ,at the middle of that line1 make an incision1 and cut at right angles upward to the top of the head4 ,next make a cut below the eye1 extending from the outer to the inner canthus4 7,fig4 #dg47 ,loosen the skin from the bone with the scalpel1 and lay bare the skull immediately over the orbit4 ,fold the flaps of the skin back and fasten them down to the skull with pins or tacks so they will not interfere with the work4 ,illustration3 ,fig4 #ej--,showing how to pry the cut bone loose4 7,page #ajb47 ,illustration3 ,fig4 #ea--8;,in removing orbital contents dissect close to the bone40 ,illustration3 ,fig4 #eb--,showing excavated orbit4 7,page #aje47 ,using the hammer and the chisel1 cut through the roof of the orbit at the middle of the supra-orbital ridge1 and continue upward for about two and one-half inches4 ,do not strike hard blows1 or the chisel may be driven through the underlying tissues4 ,listen for the peculiar sound that is heard when the bone has been completely penetrated2 then remove the chisel4 ,continue until the full distance of two and one-half inches of bone has been separated4 7,fig4 #dh47 ,now1 begin at the upper end1 and cut through the bone downward to the right for about two inches toward the outer canthus4 ,a similar line should be cut on the right of the centre line toward the inner canthus4 ,this will mark out two irregular1 triangular-shaped pieces of bone4 7,fig4 #di47 ,remove the piece on the right-hand side by prying it off4 7,fig4 #ej47 ,the left-hand piece should be pried loose and then carefully cut away with the scalpel1 so that the pulley through which the superior oblique muscle runs its tendon1 will not be injured4 ,in removing the orbital contents1 dissect close to the bone 7,fig4 #ea71 so that the periosteum will also be removed1 and form a sort of sac or capsule in which will be contained the eye with all its extrinsic tissues4 ,if difficulty is experienced in getting at the posterior parts of the orbit1 it will be best to cut away as much more of the obstructing bone as is necessary4 ,in this way the 8capsule0 containing the eye1 its six muscles1 the lacrimal gland1 and both eyelids1 all in situ1 will be removed4 7,fig4 #ed47 ,as the orbital entrance of the optic nerve is neared1 care must be exercised not to cut into this 8capsule10 or sever any of the muscles4 7,fig4 #eb shows the excavated orbit4 ,fig4 #ec shows an anterior view of the enucleated eye4 ,fig4 #ed is a side view of the enucleated eye47 ,illustration3 ,fig4 #ec--;,anterior view of the enucleated eye4 ,illustration3 ,fig4 #ed--,showing the enucleated eye1 its muscles1 and its accessories1 all in situ4 ,,ophthalmoscopic ,,examination ,by practising on an enucleated eye1 one may gain considerable ability in the use of the ophthalmoscope1 and also learn to recognize the blood-vessels and other important parts of the retina4 ,to do this1 the eye to be examined must be very fresh1 for only in this condition will the cornea and lens be sufficiently clear to permit rays of light to enter the inside of the eye4 ,however1 since the pupil is oblong in shape1 and often only a narrow slit--but several millimetres in diameter--the field presented for observation is a rather limited one4 ,to increase the pupillary aperture1 take a pin1 and force the point through the cornea about three or four millimetres from the corneo-scleral junction1 and at right angles to the direction of the parallel edges of the pupil4 ,after the pin has been pushed through until it has reached to within a short distance 7one millimetre7 of the edge of the iris1 carefully pick up the iris by raising the pin into a position perpendicular to the cornea1 and force the pin further down into the eye4 ,the pupil will have been enlarged on one side4 ,do the same thing on the opposite side1 and at each extremity of the pupil4 7,fig4 #ee47 ,illustration3 ,fig4 #ee--,showing one pin before the iris has been picked up and pulled back1 and three pins after the iris has been picked up and pulled back4 ,illustration3 ,fig4 #ef--,showing method of gathering up the extrinsic tissues in order to get rid of the pucker in the cornea4 ,the pupil will now have been made square1 and so large that no difficulty will be experienced in reflecting either light into the eye1 or in examining the inside of the eye4 ,care must be taken not to lacerate the anterior surface of the lens when the iris is drawn back by the pins4 ,putting the pins into the cornea1 and using them as levers with the point of entrance in the cornea as a fulcrum1 will pucker the cornea considerably1 and a good clear fundus cannot be obtained4 ,this is easily overcome4 ,simply gather up all the tissues surrounding the eye1 force them backward1 and hold them firmly with the fingers of the left hand4 7,fig4 #ef47 ,the right hand is then free to handle the skiascope or ophthalmoscope1 so that the interior of the eye may be thoroughly examined4 ,another way to prepare an eye for ophthalmoscopic examination is as follows3 ,go to a slaughter house and procure a beef eye from an animal that has been killed but a few minutes previously4 ,placing the eye immediately into an #h per cent4 solution of cocaine and leaving it there for about an hour will dilate the pupil to such an extent that work with the ophthalmoscope will be made very easy4 ,this1 as indicated1 can be done only with an eye that is very fresh4 ,illustration3 ,fig4 #eg--,showing window cut in sclerotic1 choroid1 and retina4 ,still another way to see the interior is to cut out a piece of the sclerotic about the size of a twenty-five-cent piece2 then pinch up and tear out the choroid and the retina under the opening made in the sclerotic4 7,fig4 #eg47 ,hold the eye1 the cornea forward1 close to a bright light1 and the image of the light will be seen upon the retina4 ,the closer the light is to the eye1 the greater the illumination will be in the interior of the eye4 ,if the opening or 8window0 is close enough to the optic nerve1 the optic papilla can be seen easily4 ,and1 if care has been taken to have the opening made midway between the two branches of the retinal artery1 the entire course may be followed4 ,the direction of the retinal artery can be determined by ophthalmoscopic examination4 ,,the ,,lacrimal ,,ducts ,to find the lacrimal ducts1 cut across the outer and inner canthi of the enucleated eye1 pushing the eye forward and the lids backward4 ,that will expose the conjunctiva of both eyelids and eye1 and also show the conjunctival fornices4 ,on the upper surface of the palpebral conjunctiva1 and near the outer canthus1 will be seen1 upon close inspection1 a number of minute openings1 usually eight4 ,these are the openings of the lacrimal ducts4 ,pins or straw that have been lubricated with vaseline1 may be inserted and pushed into these openings for a considerable distance1 and the course of the ducts then can be traced easily4 7,fig4 #eh47 ,illustration3 ,fig4 #eh--,showing how pins may be inserted in the lacrimal ducts4 ,,the ,,lacrimal ,,gland ,the lacrimal gland is easily distinguished by its pink appearance4 ,there are two parts1 inferior and superior4 ,the gland lies directly over the eye and near the outer angle of the orbit4 ,in the enucleated eye1 it will be found to lie near the outer canthus and over the eye4 ,the gland may be easily dissected out of its position and then examined more closely4 ,a hand lens will show the racemose construction of the gland4 ,if the gland is cut in two1 the racemose construction may be seen even better4 ,,the ,,capsule ,,of ,,tenon ,to dissect the capsule of ,tenon1 it is necessary to carefully remove the superficial fat and connective tissue4 ,in text-books and illustrations1 the capsule is usually shown as a definite sac-like membrane of considerable thickness1 with all its parts well defined4 ,the dissector will soon find that the capsule is not discerned so easily4 ,it will be found to be the thin1 semi-transparent1 fibrous membrane that surrounds each muscle1 as well as the 8posterior two-thirds of the eye10 and is continuous anteriorly with the ocular conjunctiva4 ,portions may be pinched up and inflated through an inserted blow-pipe4 ,this will help to merely demonstrate its location and parts4 7,fig4 #ei47 ,illustration3 ,fig4 #ei--;,enlarged to show part of the ,capsule of ,tenon blown up4 7,page #aaf47 ,,the ,,superior ,,oblique ,,muscle ,,and ,,its ,,pulley ,after the lacrimal gland has been dissected away1 a beginning will have been made for cutting away the fat and the connective tissue4 ,the first thing to do then is to locate the superior oblique muscle4 ,try to keep track of which part of the eye is the inner side4 ,having located the inner side1 feel along the top for a little hard eminence4 ,that is the pulley4 ,begin to dissect around the pulley1 not through it1 and then follow the muscle along to its origin2 do not separate the muscle from its origin4 ,when the superior oblique is completely freed1 the action of the muscle may be readily demonstrated by holding the 8ring0 or tendinous pulley with the fingers of one hand1 while the muscle is pulled backward and forward with the other4 ,,the ,,other ,,extrinsic ,,muscles ,with the dissection of ,tenon's capsule and the superior oblique muscle1 the work of isolating the other extrinsic muscles will have begun4 ,this work needs no directions except a warning to be careful not to injure the pulley of the superior oblique1 and to be careful not to cut away the inferior oblique4 ,the inferior oblique will be found to be near the 8pulley40 ,if the dissection is not carried too close to the origin of the recti muscles1 all the muscles may be kept in place4 ,if the eye has not been previously subjected to the hardening influence of formaldehyde1 it may be put into a #e per cent4 solution1 and at the end of ten or twelve hours the muscles will have become rigid4 ,they can then be better studied1 and may be kept indefinitely4 7,fig4 #fj47 ,illustration3 ,fig4 #fj--,showing the tendinous pulley of the superior oblique muscle and the extrinsic muscles4 ,,the ,,three ,,tunics ,,of ,,the ,,eye1 ,,the ,,hyaloid ,,and ,,its ,,attachments ,this dissection is a rather difficult one to make1 and requires patience4 ,illustration3 ,fig4 #fa--;,cutting through the iris4 ,prepare an eye by placing it in a #e per cent4 solution of formaldehyde for about ten days to two weeks4 ,remove all the outside tissues4 ,cut away the cornea1 as in the dissection for the choroid or the retina4 ,loosen1 as far back as possible1 the sclerotic from the choroid4 ,remove the sclerotic for about #aj mm4 back of the equator of the eye4 ,with the tweezers pick up the pupillary edge of the iris4 ,using the small pointed scissors1 cut through the iris4 7,fig4 #fa47 ,lift either one of the cut edges of the iris1 and1 with the sharp edge of the scalpel1 gently scrape the processus zonuloe free from the ciliary processes1 cutting through the ciliary ring as the ciliary processes are detached from the hyaloid 7processus zonuloe74 7,fig4 #fb47 ,illustration3 ,fig4 #fb--,scraping the ciliary processes free4 ,showing1 also1 the choroid cut around the ciliary ring4 ,great care must be taken not to thrust the point of the scissors into the hyaloid1 suspensory ligament1 or vitreous1 else the lens may become detached4 ,after the iris with the processes has been removed1 pinch up with the tweezers a fold in the choroid4 ,make an incision with the fine-pointed scissors1 and begin removing the choroid to within about #e mm4 of the cut end of the sclerotic4 7,fig4 #fc47 ,care must be taken not to penetrate the underlying retina while making this part of the dissection4 ,illustration3 ,fig4 #fc--;,cutting away the choroid4 ,after part of the choroid has been removed1 the specimen will show the three coats of the eye in layer-like arrangement1 the hyaloid and lens4 ,the lens may now be cut away1 if the specimen is preferred without it4 ,removing the lens before this time is unwise1 because it acts as a protection to the other tissues while the specimen is being handled during the dissection4 ,this specimen will show to the best advantage if it is suspended in a jar containing a #e per cent4 solution of formaldehyde4 ,figure #fd shows the specimen4 ,illustration3 ,fig4 #fd--;,a4 ,optic nerve4 ,b4 ,sclerotic4 ,c4 ,choroid4 ,d4 ,retina4 ,e4 ,hyaloid4 ,f4 ,lens4 ,,index ,a ,accessories1 ocular1 #ie ,alcohol as a preservative1 #cd ,alcohols1 method of running through1 #eh1 #ei ,anterior chamber1 #ej1 #ea1 #hf1 #ij half of eye1 #di half1 removing vitreous from1 #di surface of lens1 #ee ,aperture1 increasing pupillary1 #ajf1 #ajg1 #aji ,aqueous humor1 #ea ,arteria centralis retin1 #dc1 #di ,arteries1 ciliary1 #gb course of retinal1 #aaa ,artery of retina1 central1 #dc1 #di hyaloid1 #dc ,b ,beef eyes1 #bf1 #bg ,beginning of dissection of orbital contents1 #ig ,benzine1 #ei ,blood-vessels of retina1 #ajf ,blowing through blowpipe1 folding retina by1 #ha1 #hb ,blowpipe1 folding retina by blowing through1 #ha1 #hb glass1 #ce using it to force out vitreous1 #gh-ha ,body1 hyaloid1 #da ,boiling crystalline lens1 #ee1 #ef ,books1 text1 #bc1 #be1 #df1 #eb ,c ,canal1 hyaloid1 #dc of ,petit1 #ce-cg ,canaliculi1 puncta1 papilla1 and nasal duct1 locating1 #ib-ie ,capsule of lens1 #cc1 #ej1 #ed of lens1 removing1 #ei ,capsule of ,tenon1 #aae of ,tenon and conjunctiva1 #aaf ,cedar oil1 #fj ,cells of processes1 pigment1 #di1 #ej ,central artery of retina1 #dc1 #di ,chamber1 anterior1 #ej1 #ea1 #hf1 #ij posterior1 #ej1 #ea1 #hf1 #ij ,chemicals1 #bb1 #bc ,chisel and hammer1 use of1 #ii-aja ,choroid1 #fb and sclerotic1 cutting them away for isolating retina1 #hc emptying1 #fi1 #gj for dissecting three tunics1 removing1 #abb from sclerotic1 for dissection of three tunics and hyaloid1 loosening1 #abj iridescence of1 #de loosening from corneo-scleral junction1 #fd1 #fe loosening sclerotic from1 #fd1 #ff1 #fg1 #fh or retina1 removing cornea for isolating1 #fb1 #fc1 #fd picking up retina and1 #cj1 #ca preparing eye for isolating1 #fb preserving isolated1 #gb removing1 #df removing lens from1 #fi1 #gj1 #ga scraping sclerotic from1 #fh separating sclerotic from1 #bg1 #bi ,cilia and other superficial accessories1 #ie ,ciliaris1 corona1 #di1 #ea orbicularis1 #di1 #ea retin1 pars1 #di ,ciliary arteries1 #gb nerves1 #gb processes1 #bg1 #cc1 #di processes free from processus zonuloe1 scraping1 #aba ring1 #ea ring1 cutting ciliary1 #aba ,ciliary1 clarifying lens1 #eh1 #ei ,coats1 preparing eye for dissection to show1 in situ1 the three1 #abj ,cocaine1 #aji ,color of processes1 #ej ,concentric layers of lens1 #ef1 #eg ,conjunctiva and ,capsule of ,tenon1 #aaf ,conjunctival fornices1 #aac ,cornea1 epithelium of1 #eb removing it for isolating choroid or retina1 #fb1 #fc1 #fd ,construction of lacrimal gland1 racemose1 #aad ,contents1 beginning of dissection of orbital1 #ig-aja dissecting orbital1 #ig-aje emptying eyeball of1 #cb1 #cc enucleating orbital1 #ajb-ajd material for enucleation of orbital1 #ig preserving of hyaloid1 #cb1 #cc1 #cd1 #cf ,cornea1 #eb and sclerotic1 #eb layers of1 #eb smoothing it for ophthalmoscopic examination1 #aji ,corneo-scleral junction1 loosening choroid from1 #fd1 #fe ,corona ciliaris1 #di1 #ea ,cortex of lens1 #ed1 #ei ,course of retinal arteries1 #aaa ,cross section of optic nerve1 #dh ,crystalline lens1 #cc1 #di1 #ec lens boiling1 #ee ,cutting away sclerotic and choroid for isolating retina1 #hc ciliary ring1 #aba cross section of optic nerve1 #dh eye for sagittal section1 #hg-hi eye in half1 #ch1 #ci iris for dissection of three tunics1 #abj optic nerve longitudinally1 #dg1 #dh ,d ,dehydrating lens1 #eh1 #ei ,demonstration of hyaloid1 etc41 #cd ,disc1 optic1 #dc ,dishes1 ,stender1 #ba ,dissected hyaloid1 #cc ,dissecting lacrimal gland1 #aad nasal duct1 papilla and puncta1 #ib orbital contents1 #ig-aje of hyaloid membrane1 #be1 #cc of hyaloid1 method of preparing for1 #bf1 #bg of orbital contents1 beginning of1 #ig-aja three tunics1 removing choroid1 for1 #abb ,dissection1 preparing eye for interior1 #ch preparing eye to show the three tunics in situ1 #abj of three tunics and hyaloid1 loosening choroid from sclerotic for1 #abj of three tunics1 cutting iris1 for1 #abj ,duct1 material for dissecting papilla1 puncta1 and nasal1 #ib papilla1 puncta lacrimalia1 and nasal1 #ib ,ducts1 meibomian gland and1 #if lacrimal1 #aab1 #aac ,e ,emptying choroid1 #fi1 #gj eyeball of contents1 #cb1 #cc ,entrance of optic nerve1 #dc ,enucleated eye1 #ajd ,enucleating orbital contents1 #ajb-ajd ,enucleation of orbital contents1 #ig-aje of orbital contents1 material for1 #ig ,epithelium of cornea1 #eb ,equipment1 #ag-bd ,examination1 ophthalmoscopic1 #ajf preparing eye for ophthalmoscopic1 #ajf-aaj smoothing out cornea for ophthalmoscopic1 #aji ,excavated posterior half1 #df1 #dg sagittal1 #ij ,extrinsic muscles1 other1 #aah muscles1 preserving1 #aai ,eye1 anterior half of the1 #di contents1 emptying1 #cb1 #cc cutting it for sagittal section1 #hg-hi for dissection of hyaloid1 etc41 preparing1 #bf1 #bg in half1 cutting1 #ch1 #ci interior of1 #ch posterior half of the1 #dj preparing for dissecting interior1 #ch preparing it for dissection1 to show the three tunics1 in situ1 #abj preparing for isolating choroid1 #fb preparing for isolating retina1 #gd1 #ge preparing for ophthalmoscopic examination of1 #ajf-aaj preparing for sagittal section of1 #hf sagittal section of1 #hf seeing interior of1 #aaj vertical section of1 #hf cutting window in1 #aaj ,eyelids1 #ie1 #aje ,eyes1 sheep and beef1 #bf1 #bg ,f ,fibres of lens1 #ef1 #eg network of vitreous1 #da1 #db ,fluid1 perichoroidal1 #dj1 #df ,folding retina by blowing air through blowpipe1 #ha1 #hb ,forcing out vitreous1 using blowpipe in1 #gh-ha ,fornices1 conjunctival1 #aac ,g ,gland1 dissecting lacrimal1 #aad lacrimal1 #aad racemose construction1 #aad ,glands and ducts1 meibomian1 #if ,glass blowpipe1 #ce ,glassware1 #ba ,h ,half1 anterior1 #di cutting eye in1 #ch1 #ci ,half1 excavated posterior1 #df posterior1 #dj posterior1 excavated1 #df preparing eye for dissecting interior1 #ch removing vitreous from anterior1 #di removing vitreous from posterior1 #da ,hammer and chisel1 use of1 #ii-aja ,humor1 aqueous1 #ea vitreous1 #cc ,hyaloid and attachments1 demonstration of1 #cd artery1 #dc body1 #da canal1 #dc dissected1 #cc membrane1 dissection of1 #be-cc membrane with contents and attachments intact1 removal of1 #be preserving contents of1 #cb1 #cc1 #cd1 #cf preserving three tunics and1 #abc ,i ,image1 retinal1 #aaj ,increasing pupillary aperture1 #ajf1 #ajg1 #aji ,inferior oblique muscle1 #aai ,instruments1 #ba ,interior of the eye1 #ch of the eye1 seeing1 #aaj ,interior section1 preparing the eye for dissecting1 #ch ,iridescence of choroid1 #de ,iridescent choroid1 #dj1 #dc ,iris1 #di1 #ea and lens1 removing1 #ge1 #gg and processes1 removing1 #aba for dissection of three tunics1 cutting1 #abj relation between processes and1 #ea1 #eb ,isolated choroid1 preserving1 #gb ,isolating choroid or retina1 removing cornea for1 #fb-fd choroid1 preparing eye for1 #fb ,isolated retina1 preserving1 #hd1 #he ,isolating retina1 cutting sclerotic and choroid away for1 #hc retina1 preparing eye for1 #gd1 #ge ,j ,junction1 loosening choroid from corneo-scleral1 #fd1 #fe ,k ,knitting-needles1 use of1 #ib-ie ,l ,lacrimal ducts1 #aab1 #aac gland1 #aad gland1 dissecting1 #aad gland1 racemose construction of1 #aad ,lacrimalia1 nasal duct1 papilla1 and puncta1 #ib ,laminated structure of lens1 #ee1 #ef ,layers1 concentric lens1 #ef1 #eg of cornea1 #eb separating outer lens1 #ed ,lens and iris1 removing1 #ge1 #gg anterior surface of1 #ee boiling of1 #ee1 #ef capsule1 #cc1 #ej1 #ed clarifying1 #eh1 #ei concentric layers of1 #ef1 #eg cortex of1 #ed1 #ei crystalline1 #cc1 #di1 #ec dehydrating1 #eh1 #ei fibres1 #ef1 #eg laminated structure of1 #ee1 #ef nucleus of1 #ee1 #ei posterior surface of1 #ee preparing the1 #ec preserving the1 #eg1 #eh removing capsule of1 #ei removing it from choroid1 #fi-ga removing the1 #ea1 #ec separating outer layers of1 #ed staining1 #eg ,ligament1 suspensory1 #cc1 #cg ,lines1 tri-radiate1 #ed-ef ,locating papilla1 puncta1 canaliculi1 and nasal duct1 #ib-ie ,longitudinally1 cutting optic nerve1 #dg1 #dh ,loosening choroid from corneo-scleral junction1 #fd1 #fe choroid from sclerotic1 #fd1 #ff-fh choroid from sclerotic1 for dissection of the three tunics and hyaloid1 #abj ,lucidum1 tapetum1 #de ,m ,material1 #ai1 #bj1 #ba for dissecting nasal duct1 papilla1 and puncta1 #ib for enucleation of orbital contents1 #ig ,meibomian glands and ducts1 #if ,membrane with contents and attachments intact1 removal of1 #be ,method of preparing eye for dissection of hyaloid1 #bf1 #bg of running through the alcohols1 #eh1 #ei ,muscle1 superior oblique and its pulley1 #aag ,muscles1 other extrinsic1 #aah preserving extrinsic1 #aai ,n ,nasal duct1 canaliculi1 puncta1 and papilla1 locating1 #ib-ie canaliculi1 puncta1 and papilla1 #ib canaliculi1 puncta1 and papilla1 material for dissecting1 #ib ,needles and pins1 use of1 #if1 #ajf1 #ajg1 #ajh1 #aji1 #aab1 #aac use of knitting1 #ib-ie ,nerve1 cross section of optic1 #dh entrance of optic1 #dc optic1 #dg optic1 cutting it longitudinally1 #dg1 #dh ,nerves1 ciliary1 #gb ,network of fibres in vitreous1 #da1 #db ,nucleus of lens1 #ee1 #ei ,o ,oblique1 inferior1 #aai pulley of superior1 #aag ,ocular accessories1 #ie conjunctiva and ,capsule of ,tenon1 #aaf conjunctiva and other superficial accessories1 #ie ,oil1 cedar1 #fj ,ophthalmoscope1 #aji ,ophthalmoscopic examination1 #ajf examination1 preparing eye for1 #ajf-aaj examination1 smoothing out cornea for1 #aji ,optic disc1 #dc nerve1 #dg nerve1 cross section of1 #dh nerve1 cutting it longitudinally1 #dg1 #dh nerve1 entrance of1 #dc papilla1 #aaa ,ora serrata1 #di ,orbicularis ciliaris1 #di1 #ea ,orbital contents1 beginning dissection of1 #ig-aja contents1 dissecting1 #ig-aje contents1 enucleating1 #ajb-ajd contents1 enucleation of1 #ig contents1 material for enucleation of1 #ig ,p ,palpebr and other superficial accessories1 #ie ,palpebral conjunctiva and other superficial accessories1 #ie ,papilla1 nasal duct1 and puncta lacrimalia1 #ib nasal duct1 and puncta lacrimalia1 material for dissecting1 #ib optic1 #aaa puncta1 canaliculi1 and nasal1 duct1 locating1 #ib-ie ,pars ciliaris retin1 #di ,perichoroidal fluid1 #dj-df ,petit's canal1 #ce-cg ,picking up choroid and retina1 #cj1 #ca ,pigment cells of processes1 #di1 #ej of sclerotic1 #df removal of1 #cd ,pinching up sclerotic1 #bg1 #bh ,pins and needles1 use of1 #if1 #ajf-aji1 #aab1 #aac ,pipette1 #ce ,posterior chamber1 #ej1 #ea1 #hf1 #ij half excavated1 #dg half of the eye1 #dj half1 removing vitreous from1 #da surface of the lens1 #ee ,preparing eye for dissecting interior1 #ch eye for dissecting hyaloid1 #bf1 #bg eye for dissection to show the three tunics1 in situ1 #abj eye for isolating choroid1 #fb eye for isolating retina1 #gd1 #ge eye for ophthalmoscopic examination1 #ajf-aaj eye for sagittal section1 #hf the lens1 #ec ,preservative1 alcohol as a1 #cd ,preserving extrinsic muscles1 #aai hyaloid1 contents and attachments1 etc41 #cb-cd1 #cf isolated choroid1 #gb isolated retina1 #hd1 #he lens1 #eg1 #eh sagittal sections1 #hi three tunics and hyaloid1 #abc ,processes1 ciliary1 #bg1 #cc1 #di and iris1 removing1 #aba color of1 #ej pigment cells of1 #di1 #ej relation between iris and1 #ea1 #eb zonular1 #bg1 #cd ,processus zonul1 #cd zonul free from ciliary processes1 scraping1 #aba ,pulley of superior oblique muscle1 #aag ,puncta lacrimalia1 nasal duct1 and papilla1 #ib lacrimalia1 papilla1 canaliculi1 and nasal duct1 locating1 #ib1 #ie lacrimalia1 papilla1 canaliculi1 and nasal duct1 material for dissecting1 #ib ,pupillary aperture increasing1 #ajf1 #ajg1 #aji ,r ,racemose construction of lacrimal gland1 #aad ,references1 #bc1 #be1 #df1 #eb ,relation between iris and processes1 #ea1 #eb ,removal of hyaloid membrane with contents and attachments intact1 #be of pigment from processus zonul1 #cd ,removing capsule of lens1 #ei choroid1 #df cornea for isolating choroid or retina1 #fb-fd choroid for dissecting three tunics1 #abb iris and lens1 #ge1 #gg iris and processes1 #aba lens from choroid1 #fi-ga lens from anterior half and other parts1 #ea1 #ec1 #ed sclerotic to show the three tunics1 #abj the retina from posterior half1 #dd vitreous from anterior half1 #di vitreous from choroid1 #gj-gb vitreous from posterior half1 #da ,retina1 #dj-gd blood-vessels of1 #ajf central artery of1 #dc1 #di cutting away sclerotic and choroid for isolating1 #hc folding it by blowing air through blowpipe1 #ha1 #hb or choroid1 removing cornea for isolating1 #fb-fd picking up choroid and1 #cj1 #ca preparing eye for isolating1 #gd1 #ge preserving isolated1 #hd1 #he removing1 #dd straightening1 #db1 #dc ,retin1 pars ciliaris1 #di ,retinal artery1 course of1 #aaa image1 #aaj vessels1 #dj1 #di ,ring1 ciliary1 #ea cutting ciliary1 #aba of superior oblique muscle tendinous1 #aag ,running through the alcohols1 #eh1 #ei ,s ,sagittal section1 cutting eye for1 #hg-hi section1 excavated1 #ij section of the eye1 #hf section1 preparing eye for1 #hf sections1 preserving1 #hi ,sclerotic and choroid1 cutting them away for isolating retina1 #hc and cornea1 #eb from choroid1 for dissection of three tunics and hyaloid1 loosening1 #abj loosening choroid from1 #fd1 #ff-fh pigment of1 #df pinching up1 #bg1 #bh scraping choroid from1 #fh separating choroid from1 #bg1 #bi to show the three tunics1 removing1 #abj ,scraping choroid from sclerotic1 #fh processus zonul free from ciliary processes1 #aba ,section of optic nerve1 cross1 #dh cutting eye for sagittal1 #hg-hi preparing eye for sagittal1 #hf sagittal1 #hf vertical1 #hf ,sections1 preparing eye for dissecting interior1 #ch preserving sagittal1 #hi ,seeing interior of eye1 #aaj ,separating choroid from sclerotic1 #bg1 #bi1 #fd-fh outer layers of the lens1 #ed ,serrata1 ora1 #di ,sheep eyes1 #bf1 #bg ,skiascope1 #aji ,smoothing cornea for ophthalmoscopic examination1 #aji ,superior oblique muscle and its pulley1 #aag ,staining lens1 #eg ,stender dishes1 #ba ,straightening retina1 #db1 #dc ,structure of lens1 laminated1 #ee1 #ef ,superior oblique muscle1 pulley of1 #aag ,surface of anterior of lens1 #ee of posterior of lens1 #ee ,suspensory ligament1 #ee ,t ,tapetum lucidum1 #de ,tendinous ring of the superior oblique muscle1 #aag ,tenon and ocular conjunctiva1 ,capsule of1 #aaf ,tenon's ,capsule1 #aae ,text-books1 #bc1 #be1 #df1 #eb ,three tunics1 removing choroid1 for dissecting1 #abb ,tools1 #ba ,tri-radiate lines1 #ed-ef ,tunics1 in situ1 preparing eye for dissection to show the three1 #abj preserving hyaloid and three1 #abc removing the sclerotic1 to show the three1 #abj ,u ,use of hammer and chisel1 #ii-aja of knitting-needles1 #ib-ie ,using blowpipe in forcing out vitreous1 #gh-ha ,v ,vena vorticosa1 #gb ,vertical section of the eye1 #hf ,vessels of retina1 blood-1 #dj1 #di1 #ajf ,vitreous1 #cc network of fibres in1 #da1 #db removing from anterior half1 #di removing from posterior half1 #da using blowpipe to force out1 #gh-ha ,vorticosa1 vena1 #gb ,w ,window1 in eye1 cutting1 #aaj ,x ,xylol1 #ei ,z ,zone of ,zinn1 #cf1 #cg ,zonular processes1 #bg1 #cd ,zonulii ,zinii1 #cf1 #cg ,zonul processus1 #cd ,transcriber's ,notes ,page #abg1 cutting window in3 either in the wrong place alphabetically1 or it is an error for window1 cutting in4 ,the 7unusual7 spellings zonuloe and zonul have been retained4 ,changes3 ,footnotes have been moved to the end of the chapter in which they are referenced4 ,illustrations have been moved out of text paragraphs4 ,some obvious minor typographical and punctuation errors have been corrected silently4 ,in some illustrations the reference letters have been accentuated4 ,page #aa1 #ab3 ,illustration numbers added4 ,page #abg1 ,gland1 racemose construction3 page number #aad added4 ,page #acj3 the entries iris and lens have been moved to their proper place2 the entry ,retin1 pars ciliaris has been moved to a separate line4