of the impression of the image carried from each eye to each side of the brain. It will be seen then that in order that there be perfect correspondence between the impressions on each visual cortex, there must be perfect harmony between the two mechanisms by which these impressions are focused. The human eye, almost immediately adjusts itself to any focal range within its possibilities. This is not accomplished by means of a screw as in a camera, but by, at least, eighty muscular processes constituting the ciliary body, R.A.C L.C. A.F. 12345 ETC. R.C. FIG. I. LEWIS-DIAGRAMATIC SKETCH OF THE CORRESPONDING R. C.-Right ciliary region. L. C.-Left ciliary region. 1, 2, 3, 4, 5, etc.-Neurons governing corresponding accommodative ciliary fibers. R. A. C.-Right center for accommodation. L. A. C.-Left center for accommodation. A. F.-Association fibers connecting corresponding nuclear neurons. and these are each again subdivided into individual fibers, so that there are certainly as many single living chords controlling the focus of the lens, as there are degrees in a circle. The center for accommodation has been located as a part of the group of cells, constituting the nucleus of the third nerve. As it has been shown that these ciliary elements act synchronously, . there must be nuclear origins for each fiber, and consequently the center for accommodation is not a point but a multitude of neurons. (See Fig. 1). The various parts, therefore, of the mechanism of vision are so interrelated that to work harmoniously they must be anatomically symmetrical and normal. If one eye is too short in its long axis, as occurs in hypermetropia, or if it is too long, as in myopia, or if the axes are incommensurate, as in astigmia, or if the eyeballs themselves are unsymmetrical as in anisometropia, or as it is essential that the visual axes shall be both directed toward the object observed, if the muscles are in a state of imbalance as in heterophoria, then the effect exerted upon the delicate muscle fibers, in an endeavor to correct by adjustment that which is organically wrong, may disturb the harmony of action and affect both the visual centers as well as centers associated with them. Now the infant does not possess at birth the function of binocular fixation. The eyes roll aimlessly for the first six weeks of life and only gradually acquire the power of working coördinately. The complete power of fusing images has usually been acquired by the sixth year according to Worth1, whose recent book is the most valuable contribution to this subject for many years. and to whom I am indebted for many of the important conclusions which I shall endeavor to outline in this paper. Among all of the complicated and accurately balanced coordinate actions, there are none in which a nicer adjustment is required than in that of seeing. It is first necessary that the cortical center governing the muscles of the neck be energised in order that the head be lifted to the right angle and turned in the proper direction toward which the eyes are to be directed. If the object is within a short range the center for convergence must cause the internal recti to pull the eyes in exactly the position that will make the visual lines cross in the plane of the object to be seen. Meanwhile the externi are holding the balance as guy ropes in order that the convergence be not excessive. In any slight rotation the obliques are working as pairs or antagonists. Coincidently the accommodative centers, which as has been shown, have a hundred or more inter relationships, cause the ciliary muscle to give the exact degree of curvature to the lens to bring the focus upon the desired point. That these involved actions may be performed at the same time or in rapid succession as may be desired, each of the centers must be directly connected by means of association fibers with each of the others and the combined activities produce the function. of fusion. That is to say, a stereoscopic effect is produced by the impressions of both eyes being superimposed in the cortex of each cuneus so exactly that as undoubtedly the cortical neurons are also connected, the sensation is excited in the brain of a single image and we have binocular vision with perfect fusion of the images. 1. Squint-Its Causes, Pathology and Treatment. By Claud Worth, F. R. C. S., 1903. If, however, as frequently happens, the mechanism by which the two foci are produced is not alike, the images are not then superimposed nor produced with equal clearness. One camera,— one eye, may be longer or shorter in its focus than the other, or the radii of corneal curvature may be greater or less in one meridian than in the corresponding meridian of the fellow eye. The images will then be unlike on the retina and the impressions uneven on the cuneus cortex. In that hemisphere, therefore, corresponding to the defective eye the impression is dull. Greater effort is made by the centers governing accommodation to get a clear impression and, as accommodation and convergence are produced together, the eye turns in. Fusion is imperfectly accomplished if at all. As a muscle which is not used soon ceases to retain its function, so an eye, or the visual center rather with which the eye communicates, ceases to have the power to see. Worth insists that if this fusion function is not restored before the sixth year, vision never is regained and the faculty is permanently lost. That this is not absolutely true is shown by the fact that sight does measurably improve under training at a later age than this; but it is, nevertheless, true that with each year after the squint becomes established, the difficulties are increased and the possibilities are limited. The pernicious teaching which one yet occasionally encounters, advising delay in the correction of a squint until the child has arrived at an age at which adequate tests may be made and glasses worn, or the yet worse advice that the deformity "will be outgrown" cannot be too strongly deprecated. By means of objective methods, notably the shadow test which is exceedingly trustworthy and the ophthalmometer, with the aid of the ophthalmoscope, an exact determination of the refraction can be made in an infant and measures should be at once undertaken to correct the existing defect on which the squint depends. The first requirement may be to use a cycloplegic in the better eye. This measurably throws that eye out of commission and compels the use of the defective and squinting one. The refraction should be at once corrected; glasses may be worn by a very young child and the relief is great and immediate. To train the fusion faculty Mr. Worth has devised an immensely practical and useful instrument which he calls the amblyoscope1. It consists of twohinged tubes so arranged with mirrors that binocular vision may be obtained when the visual angle has a convergence of 60 degrees or a divergence of 30 degrees. It is therefore, possible if poten1. See Fig. 2, p. 252. tial fusion exists to bring the visual axis together and after correcting unequal refraction to compel the defective eye to make the effort to see. It is astonishing how rapidly an amblyopic eye may be trained to a point of normal visual acuity by this method, and a defect that must otherwise soon become permanent and established be overcome. The conclusions therefore, are: 1. That no period is too early for the recognition and attempted correction of a threatened or imminent squint. For developing fusion function and improving visual power in young amblyopic eyes. 2. That when recognised, refractive differences should be adjusted at the earliest period at which glasses may be worn. 3. That fusion training should be at once employed under the direction of the surgeon, in order that incipient or established amblyopia may be corrected before the defect becomes fixed and incurable. 4. That surgical intervention should be undertaken as soon as its necessity becomes established, and should consist of tenotomy or advancement or both, at such a time as will permit perfect fusion, if correction with glasses and fusion training by the amblyoscope will not suffice to correct the existing deformity. 454 FRANKLIN STREET. THE SOCIETY PROCEEDINGS. Buffalo Academy of Medicine REPORTED BY WM. IRVING THORNTON, M. D., Secretary. HE regular meeting of the Section of Medicine of the Buffalo Academy of Medicine, was held in the Academy rooms, Public Library Building, Tuesday, September 15, 1903. The meeting was called to order at 8.45 p. m. by the chairman, DR. ARTHUR W. HURD. DR. GEO. E. FELL presented a paper entitled, LAKE AND RIVER CURRENT OBSERVATIONS AND THEIR VALUE TO OUR CITY. The occasion for this investigation was the epidemic of typhoid fever at the Steel Plant district, which is drained by Smokes Creek, whose waters, it was feared, polluted Buffalo's water supply; also for the reason that a new intake pier at the Horseshoe Reef was being contemplated. A number of floats were placed in the lake, one a mile out from Smokes Creek; others at various positions outside the breakwater, one of the latter being one thousand feet west of the red light. The first passed between the breakwalls into the inner harbor. The latter floated down the river, 320 feet east of the intake pier; another float started at a point at the intersection of the projections of Jersey Street and the old breakwall and passed into the intake pier. This point, however, in the judgment of the essayist, was too far out to be contaminated by Smokes Creek. He, therefore, concluded that Buffalo's water supply was not endangered because of typhoid at the Steel Plant. THE DR. A. L. BENEDICT read a paper entitled, HAMBURG FILTER PLANT AND FILTRATION OF WATER IN giving an outline of the construction of the filter plant and method of cleansing the same. In discussing Dr. Fell's paper, DR HOPKINS said we should. consider that Lake Erie is very superficial, and that there are many special currents differing from the general currents, as observed by the essayist, which might cause the water from Smokes Creek to contaminate our city water. While he believed that part of the water passed between the breakwalls into the inner harbor, |