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importance-first, of a regular attendance in the wards, at the clinical lectures, and at post-mortem examinations; and, secondly, of careful case-taking. Bear in mind that when you have to undertake the management of cases on your own responsibility, you will have to watch and treat the symptoms which arise from day to day. Your attendance will not then be of an uncertain and irregular character; for if it be, your patients will soon dismiss you. As, then, you would wish to be able to estimate the daily progress of your future patients, watch carefully the daily progress of those whose treatment you witness here. Record their cases in your note-books, that they may become the more firmly impressed on your memory.
INFANTILE PARALYSIS AND ITS
BY RICHARD BARWELL, F. R. C. S.,
SURGEON TO CHARING CROSS HOSPITAL.
nine might be safely injected in much larger quantities than had been imagined, and that I could fearlessly begin by giving even children five times the dose hitherto considered as the maximum-namely, five half-minims, or one-twentieth of a grain. But it was not alone with children that I thus worked: all local paralyses appeared to me proper subjects for these experiments. The results are singularly confirmatory of the idea which I had formed, that eccentric paralyses would be very amenable to the local action of strychnine. Thus, several cases of facial paralysis, several of paralysis of the wrist (independent of syphilis or of lead-poisoning), and others, have yielded to a few injections, after months of galvanism, internal administration of strychnine, and other remedies have failed. Several of these cases have been published;* here I will give only two short résumés in illustration of the power of the drug thus employed.
J. G. M, aged thirty-eight, consulted me on the 14th January, 1872, on account of lameness from paralysis in both legs. In the early part of 1865 he had, at Malta, Mediterranean fever, which appears to be a variety of gastric fever. This was followed by acute rheumatism without heart affection. The recovery was slow, with many relapses. He does not know what muscles or limbs may have been paralysed when he was in bed; but when he began to get about, all the muscles in front of the tibia and all those in the ball of the thumb had lost power, except those inside the long flexor tendon, and even these were very much weakened. General wasting also of these muscles had taken place. His gait was very awkward and insecure; and he came to ask me about the desirability of instruments to assist him in walking, having found galvanism almost constantly employed utterly useless.
I explained the above described use of strychnine, and proposed that it should at all events have a trial. He consented, and I began with the right leg, which was rather less wasted than the other. The dates and quantities of injection were as follows:-Jan. 14th, seven half-minims; time of the first injection the limb began to improve, both 17th, eight; 19th, ten; 21st, twelve half-minims. From the in power and in size. I then took the left leg-the more wasted of the two; but as the last injection had caused a slight sense of uneasiness I used a less quantity-namely, on Jan. 24th, eight half-minims; 26th, eight; 29th, eight; 31st, eight; Feb. 2nd, ten; 5th, ten half-minims. Here also improvement commenced with the first injection, as evidenced the outlines here given. The broken line shows the condition on Jan. 24th; the dotted line, the condition on Jan. 31st; and the plain line, that on Feb. 10th. Each outline
HOWEVER valuable it may be to learn that infantile paralysis is, in its early stages, an affection essentially curable by the two forms of galvanism, yet it must be acknowledged that cases very rarely come under proper treatment until this easier phase of curability has passed away. A better knowledge and insight into the natural history of the malady may cause it to be more generally attacked in time; but it is too much the prevalent habit to believe in a temporary paralysis on the one side, or simply in incurability on the other-to begin by buoying up delusive hopes, and then to foster a vague despair, and, while doing nothing material, to allow all the best hours of action to pass away. With the lapse of time the limb loses power, not merely of movement, but also of circulation and nutrition; it becomes permanently cold and bluish in tint; it stops grow-by ing, and soon is shorter as well as thinner than the sound one. If the whole leg, for instance, be affected, it has a singular knack of outward rotation in standing, or in sitting of rolling outwards from the nurse's lap to such an extent that the inside of the thigh presents forward, and often the sole of the foot, the toes being pointed, is visible from the front. In this stage, though certain muscles may retain some irritability, deformities are arising with great rapidity, and permanent lameness already has commenced to assert itself. Yet even now cure is quite possible, but will require longer persistence of treatment, and the peculiar use of strychnine, after the manner whose introduction to the profession I will shortly describe.
Being strongly convinced of the peripheral origin of infantile paralysis properly so called, yet finding that in cases of some little standing no progress was effected by galvanism, neither was the internal use of strychnine followed by any benefit, I determined to employ the drug locally. For this purpose I injected into the moveless muscles or their neighbourhood the Pharmacopoeial solution of strychnia. Here, too, I was disappointed; the topical effects were nil, even while on the verge of constitutional symptoms. It appeared to me that I must retard absorption, and thus, while keeping the drug longer in the part to be influenced, avoid its a tion on nerve centres. I therefore procured a very dense solution-viz., two per cent.,-and began a series of cautious experiments. I used a syringe with a piston graduated into half-minims, over which runs a screw stop; each turn and a half of the screw corresponds to a halfminim, hence each such quantity can easily be divided into six parts, and, with more care, into twelve; as each halfminim of solution contains 1 gr., subdivision is rendered easy and all precautions facile. In my experiments, however, I very soon discovered that, thus largely dissolved, strychThis is the "jambe de Polichinelle" of French authors.
was made by cutting out a piece of stiff card-board to fit on the limb 10 above the inner malleolus so accurately as to leave nowhere any interval between its edge and the surface, yet nowhere to mark or impress the skin. The forms thus obtained were then accurately reduced to scale.
In equal degree with the restoration to shape did voluntary power return. The limbs are not yet as strong as normal members, but this is a mere matter of time.
M. E. B, aged forty, came under my care on the 17th of October, 1872, with paralysis of the right side of the face. On the 31st of August she, in washing her face, put her Clinical Society's Reports, vol. ii,
finger twice into the right eye. To this she attributes the paralysis; it was doubtless a consequence. In the evening her husband saw the "mouth go round." She has been since the 1st of September under treatment, taking tonics and strychnia, and using galvanism.
Oct. 17th.-The right side of the face is perfectly immobile; the mouth much drawn to the left; the right eye wide open. I tested the irritability of the muscles with a rather sharp galvanic current. There was some action in the platysma, but nowhere else. I injected seven halfminims of the 2 per cent. solution of strychnia; no constitutional effects.
27th. This patient remained away ten days, as she was afraid of what she called "the operation." To-day, however, I found improvement, which she said had immediately followed the injection, but had not continued after the first three days; hence she returned, and 1 injected eight half-minims. On Oct. 29th I injected ten half-minims, on Nov. 1st ten, on Nov. 3rd ten, on Nov. 5th twelve, and on Nov. 7th twelve.
I have noted here nothing beyond the mere injections, as steady improvement is the history of the case. After ten injections she was quite well, the mouth remained straight, and she could close the eyes perfectly. I saw her only a week or two ago, and she remained quite well.
It is to be observed that in this and in other cases of adult eccentric paralysis voluntary motion has been perfectly restored, while galvanic irritability has remained absent for a considerable time. In other cases a response to the continuous current has early arisen, but only after voluntary movement became markedly improved. The behaviour of infantile paralysis is herein different, and response to the electric current from one or the other apparatus precedes any return to voluntary movement; but this also comes after a little while. My method of proceeding with infants is as follows: To begin by galvanising each muscle separately, and to note the amount (if any) of electric irritability, or its entire absence. The former organs may almost take care of themselves, a little galvanism being passed through them occasionally. The others should be galvanised two or three times, and closely watched to detect any sign of twitching. Now during all this time it is most essential not to frighten the child, or give more pain than necessary. It is impossible to make much out about the paralysed muscles of a limb while the part is being jerked from above by violent movements of the trunk. Although we do not expect electric mobility to come into the muscles which have long been paralysed, it is well thoroughly to test them. And now, having determined to use strychnia, I begin with from three to six half-minims, according to my patient's age; and, selecting an opponent to that muscle which is most contracted, I inject the solution into its substance, or sometimes over the place of entry of its nerve. I continue such injections two or three times a week for a certain period, and then try the muscles again. They nearly always respond first to the constant current, and usually soon after this a small amount of voluntary power becomes perceptible. The injections must not be discontinued as soon as the galvanic or nerve irritability is established; brisk response to the former should at least be secured.
L. C, aged six years and six months, was paralysed in the left leg sixteen months ago, there having been neither previously nor afterwards any severe illness. For the first rubbing. During the last six months galvanism and the internal use of strychnia have both been extensively used; indeed, on one occasion the drug was pushed so far as to produce tetanic spasms.
ten months nothing was done except tonics and occasional
She came to me on the 6th of June, 1870. The left leg was shrivelled and utterly useless. When she was supported by her nurse on the sound leg, the other hung impotently down. By a peculiar jerk of the body, common to all these children, she could make it swing; and the psoas being intact, or nearly so, enabled her to hitch it a little for ward. The limb was always cold-blue in places, pink in others. The muscles were so wasted that the limb looked barely thicker than the bone should be. There was no response to even strong galvanic currents. Three minims of strychnine solution were injected.
I injected this child with strychnia twice a week for three months before I got any response to galvanism. When the response began I left off the injections and the irritability
decreased markedly. I then, in October, recommenced the use of strychnia, combining it with galvanism, and this treatment was continued for five months. In March, 1871, I discontinued the injection. Considerable voluntary irritability of muscles had now been established, and very easy response to the continued current. In May, the induced current began to tell. The rest of the case is a mere question of time. The patient is still improving rapidly.
J. R, aged seven years and three months, was brought to me on February 3rd, 1871, with a deformity of the right foot, which I have named pes cavus, arising, as I have shown, from paralysis of the gastrocnemius, and frequently also of the muscles in front of the tibia. These paralyses were present in this case. The leg was a good deal wasted, but not livid. It easily lost temperature on cold days, but if kept well covered remained warm. The paralysis came on when she was two years old without illness of any sort; the deformity formed itself gradually. She has been treated, among other methods, with galvanism and internal doses of strychnine.
I injected five half-minims to begin with, and twice a week I continued this method, increasing to eight half - minims. At the end of seven weeks the muscles became amenable to the continued current. The use of galvanism was combined with the injection. At that time viz., three lunar months-the muscles were voluntarily mobile, and the size of the leg was very much increased. The child walked very fairly well. The deformity was treated in a manner to be described in the sequel.
These two cases mark strongly a difference to be found in paralysed limbs-a difference which is of the very greatest value for prognostic purposes. In the one the extreme wasting and the great loss of temperature marked almost the utmost limit of nutritive disorder; in the other, although paralysis had lasted as long, or even longer, and though the limb was greatly wasted, yet the skin was not so cold nor so livid; the muscles gave, when pinched, some idea of resiliency, and were not like either. soft paste in a sausage skin, or like bundles of cord, as in the former case. Now in these less livid cases, as it is certain that muscular degeneration has not gone so far, the chances of recovery within a moderate time are very considerable, however long the malady may have lasted. Of the other class I would speak with all caution. I have met with other cases besides that of L. C just quoted, which leads me to believe them curable, if sufficient care be employed for a long period. But we have to do not merely with malady. Three other conditions may, and do, often interfere-viz., convenience, patience, and moneyto one or the other, sometimes to all of these, the best devised therapeutics will be forced to yield.
NOTES OF VISITS TO FOREIGN BATHS. BY JOHN MACPHERSON, M.A., M.D.
VI.-MUD BATHS, PINE FORESTS, AND PINE BATHS. MUD BATHS were at one time used at Weilbach, but I believe are no longer so. I ought, perhaps, sooner to have said something of this variety of baths, as they are in use at several of the baths I have mentioned, such as Driburg, Meinberg, Eilsen, Nenndorf, Pyrmont, and Spa.
The use of mud baths in Germany was unknown till the commencement of the present century, and it is only in the last twenty-five years that it has become so popular. The practice, however, is an ancient one, not unknown to the Romans, who employed the slime deposited from baths
and from mineral waters.
It seems to be by no means improbable that the uses and advantages of this sort of bath may have first suggested themselves to some one who had witnessed the immersion of buffaloes in mud, and observed the gratification they appear, in common with pigs, to derive from it.
The varieties of mud baths may be considered to be :1. When the mud or slime deposited from mineral waters is used for poultices or complete immersion; this is the oldest form, as at Acqui or at St. Amand.
2. Simple peat-earth, or other earth.
3. Peat-earth impregnated with mineral water, of which Franzensbad offers a good type.
In all cases the earth is carefully sifted, so that large particles may be got rid of, and is usually exposed to the frost of the previous winter. The homogeneous mass formed of the mixture of this earth with water, or mineral water, contains insoluble salts, carbonates and sulphates of lime and of magnesia, fine sand, in some instances a little oxide or sulphate of iron, vegetable matters with some tannin, humine and humic acid, occasionally acetic or formic acids, and sometimes a large quantity of infusoria; it usually gives off a good deal of carbonic acid gas.
The capacity of this mixture for caloric is less than that of water; the patient can, therefore, bear a greater degree of heat in it. The baths are usually of a temperature of 97° to 117° up to 124°.
As to their physiological action on the system, these baths are generally a strong stimulant to the skin, and they seem to be so, partly from their heat, and partly from the increased pressure, and even a certain amount of friction, which act mechanically. No portion of the earthy part is absorbed, but there must be absorption of gas, chiefly of carbonic acid, both by the skin and the lungs. The use of these baths, as might be expected, may, when protracted, produce swimming in the head and singing in the ears; when long continued it often brings out rashes, is believed to waken up old inflammations, and sometimes induces a feeling of weariness and distaste for food.
Although the theory of the physiological or of the therapeutic action of mud baths is very imperfectly understood, yet there is no question that they are often extremely useful in general torpor and atony of the system, in old thickenings and affections of the joints, also in anesthesias, paralyses, and neuralgias. Kisch bears testimony to their great efficacy also in enlarged liver, still more in enlarged spleen, and in chronic affections of the uterus and its appendages, especially when supported by the internal use of the Marienbad waters.
Simple peat-water baths are used in some institutions abroad, as on the Untersberg Moor, near Saltzburg; but of their special efficacy there are no satisfactory accounts, nor am I inclined to believe in them. They might be had ad infinitum in Britain.
I shall pass by sand baths, although they were employed by the ancients, especially in dropsy, and though their use has been revived by the Germans in some towns and many seaside places. Among these last may be mentioned the little island of Norderny, on the coast of Hanover, a visit to which affords, from the novelty of the sea, such intense delight to Germans from the interior.
lithium. Although I observe that some late writers think
In the favourite Murg valley, at a short distance from
Before entering further into the Black Forest, it may be convenient to make a few remarks on pine woods.
Although some forests are regarded as sources of malaria, and oak trees and hazel bushes have been counted insalubrious in Europe, like the tamarind tree in the East, yet the air of pine forests appears always to be grateful to the lungs, and has been considered wholesome, although of its absolute curative influence there is little evidence, and, indeed, it must be difficult to procure such. The idea of pine forests exercising a balmy influence on the lungs is a very ancient one. Pliny considered that the air of pine forests was more useful in phthisis and in convalescence from acute diseases than the voyage to Egypt, recommended in such cases in those days. Both Bournemouth and Arcachon at the present day owe a good deal of their reputation to their pine woods. The air of the latter is said to be distinctly sedative. On the whole, then, the air of the pine woods of the Black Forest may be regarded as an element entering into the consideration of the value of its baths.
But besides merely inhaling the air of its forests, people have of late years made much use of the products of pine in baths, vapour baths, and inhalations. Even this is not entirely modern; for the ancients recommended chiefly the internal use of decoctions of strobili and of pine tops, and thought pine nuts very useful in diseases of the chest; and at a more modern time, besides the internal use of drinks made from the spruce and the tar-water so long in vogue, we had inhalations of tar and of various resins.
The ancients did, indeed, recommend in gout baths of water in which cedar wood had been boiled, but the use of the pine-extract bath is quite modern. It has spread rapidly, and is now in use at many of the places I have already mentioned; for instance, at Gleisweiler, Rehburg, Liebenstein, Ruhla, and Eisenach. These aromatic extracts are procured from various pines-as from the Abies bath-excelsa or Norway spruce, Pinus vulgaris or silver fir, Pinus sylvestris or Scotch fir, Pinus maritima or Bordeaux pine, the Weymouth pine, also from the common larch, and the most fragrant of all, from P. pumilio, the mountain pine. The baths vary considerably in strength and in odour, according to the way in which they are prepared.
I cannot help remarking, in passing, that if we were loving people, like the Germans, we have every opportunity of having our sand or turf baths; we have all the advantages the Germans have for them, and I do not see why they should not be started by some enterprising individual | or company, especially as it would be easy to select a place, which could also supply the products of the pine for another class of baths, now very popular, of which I shall presently speak. I see no reason why these artificial baths should not be supplied just as efficiently at home as abroad.
I paid Baden Baden a visit of some days. If Ems be the pearl, Baden is undoubtedly the queen of German wateringplaces. Although it is a resort for pleasure at least as much as for health (of its 40,000 annual visitors about one-tenth use its waters), its unrivalled situation and natural beauties, and its immense supply of warm water, must always recommend it. Although the amount of solid constituents present in the waters is small (and they have only 165 grs. of common salt in them), yet, if one were even to view the waters as indifferent ones, their temperature, varying from 115° F. to 154°, must always make them applicable in a great variety of cases, especially in the more chronic forms of gout and rheumatism, and in the affections of declining years, which hot waters suit so much better than cold ones. But I shall not say much of a place so well known as this. All the establishments of the place, including the Trinkhalle, one of the newest, are on a magnificent scale; and to make up for the prospect of the tables closing with this season, the municipality is erecting large vapour and swimming baths. The specialty of Baden for gout is to be found in the Murquelle, which, in its 24 grs. of solid constituents, contains 15.5 of common salt and 2.3 grs. of chloride of
The commonest way of making the bath is by adding to common water a certain quantity of the decoction got by passing steam through the young pine-tops.
I found a bath at the temperature of 84° very pleasant, and the smell grateful. It was scarcely stimulating to the skin, but felt warmer than water at the same temperature would have done. The heat of the bath and the quantity of resinous matter may be increased at pleasure.
I did not try a vapour bath, but it is said to be more stimulating and exciting, and it requires to be used with some discretion. In it the vapour is of course applied to the skin, and a portion of it is also inhaled.
But we may not only inhale air naturally loaded with the aroma of pines. There are various processes-for instance, of pulverisation of water-by which the air is impregnated. The balsam of the mountain pine, as prepared at Reicherhall, is said to be the most agreeable of all, and it is sufficient for purposes of inhalation to steep a piece of paper in it and hang it up in the room. It is a generator of ozone.
These inhalations are said to be useful in catarrhs and phthisis; but the baths, whether of water or of vapour, are much more powerful agents, and there seems to be little question that they are of great use in muscular rheumatism, (especially the vapour baths,) in certain anæmic conditions, and in spinal irritation.
One other product of the forests I must mention. In
some places patients are packed up in leaves of the birch tree. This produces profuse perspiration, and is said to be found useful in rheumatism and even in some dropsies. I have already said, Why are mud baths not used in England? I may now add, Why are not pine baths? Why should we not have them at Bournemouth, Sunninghill, or Weybridge, and many other places in England? In Scotland, Dunkeld, Ballater, and Crieff are particularly suited for them. Wales and Ireland offer various suitable localities. And in some instances, as at Ballater, you might not only have mud baths, but baths saturated with chalybeate waters-not that I individually attach much importance to the latter addition; and where are birch leaves to be got better than on Dee-side for those who have a fancy for such a mode of packing?
(FOR MEASURING THE FIELD OF VISION.) BY ROBERT BRUDENELL CARTER, F.R.C.S., OPHTHALMIC SURGEON TO ST. GEORGE'S HOSPITAL, AND SURGEON TO THE ROYAL LONDON OPHTHALMIC HOSPITAL.
In many of the diseases of the eye that superficially appear to be chiefly local in their character, and in numerous cases also in which defects of sight are manifestly due to the reaction of central nerve lesion, the power to measure the field of vision with accuracy and readiness is of the greatest importance to the practitioner. In some instances the extent and shape of the field will at once determine a diagnosis that must otherwise have remained doubtful for an uncertain period; and in many the same data will afford the only trustworthy evidence with regard to improvement or retrogression. On these grounds the practice of perimetry has long been cultivated by ophthalmologists, and has lately been recognised as essential by physicians engaged in the study and treatment of diseases of the nervous system.
The early attempts at measuring the field of vision were of a rude and primitive character. A small white cross was marked on the centre of a black board, which was hung against a wall. The patient was placed with the eye under examination level with this cross, and at a measured distance of from eight to twelve inches away from it. He was directed to look steadily at the centre of the cross, which was called the "fixing point," and the other eye was closed or covered. The operator, armed with a black wand having a white tip, and with a piece of chalk, stood behind or at the side of the patient, and drew the white tip of the wand slowly along the board, from its margin towards its centre, in successive directions, usually first in a vertical line, next in a horizontal, and then in two lines intermediate between the former ones. The patient was directed to speak as soon as the white tip came into view, and at this point a chalk dot was made on the board. The patient was directed to speak again as soon as the white tip, in its onward movement towards the fixing point, became distinctly visible, and here a second dot was made. When the examination was completed there were two chalk dots on each meridian of movement. A line uniting all the external dots would show the absolute boundaries of the field of visual perception, and a line uniting the internal dots would show the boundaries of the field of distinct vision.
The maps afforded by this process were of great value, especially in the earlier studies of glaucoma and of nerve atrophy; but the process was open to the objection that the eye of the patient, which was concealed from the view of the operator, was apt to wander from the fixing point towards the moving object, and thus to vitiate the whole result. To meet this difficulty, Professor Donders made a hole in the centre of the board, and placed it in a vertical frame adapted to stand upon a table. The patient was directed to look through the hole at the eye of a second person suitably placed upon the other side of the board; and this second person gave notice if the eye under observation wandered. It is manifest that a certain amount of care and accuracy would be required from the second ob
server, and that the method, however occasionally useful, would render perimetry dependent upon the presence of at least a moderately skilled assistant. The flat board system, moreover, is open to the objection that the central fixing point is nearer the eye than any lateral portion of the surface.
To obviate these inconveniences several contrivances have from time to time been suggested; but that which has found most general acceptance is the perimeter of Professor Förster, of Breslau. It consists of a strong wooden platform, measuring fifteen inches by nineteen, supporting at one end a double chin-rest, and having at the other a stout, upright iron pillar. This pillar carries a semicircular iron band, two inches wide and of twelve inches radius, placed with its concavity towards the chin-rest, and turning freely at its middle point on a horizontal axis, so that it can be placed vertically, horizontally, or in any intermediate position. A movable slide carrying a white spot, travels freely to and fro over the concave face of the band, and is worked by an arrangement of cords and pulleys set in motion by a winch-handle. A rod proceeding from the base of the chin-rest carries a slender stem which is placed close to the band, which turns freely right or left, and on which slides a small ivory ball. The chin of the patient is placed on the chin-rest, on the proper side for the eye under examination, and (the other eye being closed) the ivory ball is used as a fixing-point, and is adjusted at to make the middle of the band correspond with the blind such a distance on the nasal side of the eye examined as spot. The same fixation being maintained, the band is placed in successive meridians, and the appearance and disappearance of the moving spot as it travels round the arc are recorded on a diagram prepared for the purpose. The is thus able to watch the direction of the eye, and to see operator stands behind the arc, opposite to the patient, and that it does not deviate from the fixing-point. The face of the arc is divided into degrees, and its axis carries a circle similarly divided, so that a map of great accuracy can in this way be obtained. The eccentric fixation-point has the macula lutea, the centre of the map, which thus correadvantage of rendering the optic disc, instead of the sponds to the ordinary course of ophthalmoscopic examina
The principle of Professor Förster's instrument is perfectly sound; but its details are excessively faulty. It is very large, heavy, cumbrous, and costly; its strings are constantly becoming loose, or twisted, or otherwise out of gear; its chin-rest is too low, the instrument being on a table, for the comfort of the great majority of patients; and the superfluous half of its semicircular band is perpetually getting in the way. Like other people, I had borne these inconveniences with more or less grumbling, until Mr. Hawksley, of Blenheim-street, one day called upon me, wishing to examine the instrument on the part of a gentleman who desired to have one. I pointed out the faults to which I have referred, and made some suggestions for overcoming them; and the result has been the construction of the perimeter I am now about to describe. It consists of a simple tripod, supporting a hollow stem (Fig. 1, A), in which a second stem (B) moves up and down, and can be fixed at any desired height by the screw (c). At the top of the stem (B) is a short horizontal axis (D), carrying the quadrant (E, E'), which turns in a complete circle, and moves with just stiffness enough to remain wherever it is placed. On the quadrant is a travelling slide (F), with a white spot; and a second independent axis is inserted in the axis of the quadrant at o, and carries a short tube, in which may be placed a stem to support the fixing point. The second or inner axis makes a complete revolution without affecting the position of the quadrant, and without being affected by it. At its attached extremity the quadrant terminates in a circular disc (E'), which is graduated into degrees at the back, and a fixed index allows the exact position of the quadrant to be read off. The quadrant is also graduated from ten degrees to ninety, on its concave face, so as to show the exact position of the slide. The fixingpoint may be either an ivory knob at the end of a wire, or, what is for most purposes better, a small disc with a central perforation, as shown at H, through which the patient looks at an object on the other side of the room, and obtains fixation without exercise of the accommodation and consequent fatigue to the eye. The travelling slide (F) may be made
the centre, until its white spot disappears, which it will usually do at about 17°. Continuing the same movement, it reappears, say at about 14°; thus giving the horizontal width of the blind spot in that meridian. Placing the white spot half-way between the two points, at 15, the vertical measurement may be taken by raising and lowering the quadrant until the spot reappears in each direction, usually at the meridians of 90° and 58°. The horizontal and vertical measurements may thus be taken in as many meridians as we desire; and an exact outline of the part of the field corresponding to the blind spot may be traced upon a chart. I have designed the foregoing chart (Fig. 2) for this purpose, and have traced upon it the gap in the field of my own right eye for an illustration.
In order to measure the field, the perforated disc must be used for fixation, and must be set so that when the patient looks through the hole at a distant point the centre of the axis corresponds to the centre of the blind spot. For this purpose, in a normal eye, the centre of the perforation should be 10° above the horizontal meridian and 171° from the axis on the nasal side of the eye under examination. The patient is then instructed to look through the hole, the instrument being placed as before, and the eye not under examination closed. The operator moves the slide from without inwards along successive meridians until he has completed the circle, and marks the limits of perception and clear vision on a chart as he proceeds. The following diagram presents two continuous line circles, as data, the FIG. 3.
spot, the quadrant is graduated at the back from eight degrees to twenty-five, in degrees and sixths of a degree: and a white spot is placed on the centre of the axis (G), to serve as a fixing-point for this particular purpose.
In order to use the instrument, the patient is comfortably seated in front of a table, with his chin supported by the rest of a demonstrating ophthalmoscope. The perimeter is then set at such a height as to have the centre of its axis on a level with his eyes, and is placed with this centre exactly in front of the eye to be examined (i. e., an inch and a quarter to the right or left of the median line, according to the eye), and exactly twelve inches distant from it. The patient closes the eye not under examination, and covers it with the hand, resting his elbow upon the table for the sak of greater steadiness.
In order to measure the blind spot, the smallest white `object is fixed to the slide, and the quadrant raised until
outer having a radius of 70°, the inner a radius of 10°. The outer dotted line shows the limits of visual perception of my own right eye. The continuous line within the inner circle shows the limits within which I can read an unknown letter of Snellen's No. 8 test types; and the inner dotted line, which shows the entire field of vision of a patient with pigmentary retinitis, may serve to illustrate some of the clinical uses of the perimeter. The last two outlines are drawn from the fixing point as a centre.
In mapping the field one may of course proceed in any order; but there are some advantages in a regular method. I usually commence from zero, with the quadrant vertically downwards, and move it upwards towards the temporal side of the eye under examination. We may of course take a chart of the field by placing our marks on meridians corresponding to the positions of the quadrant (e. g., below the centre when the quadrant is downwards); or a chart of the percipient portion of the retina by placing the marks in contrary positions (e. g., above the centre when the quadrant is downwards). To render the charts universally intelligible the same plan should be adopted by all observers. Of the two named, the former is clearly the best: first, because it is the more simple; secondly, because the chart