treatment.

These are considered elsewhere; but there are cer

taiu defects common to all eyes which may be styled

а.

IRREMEDIABLE OPTICAL DEFECTS.

These are given by Helmholtz, and are chiefly as follows:Lack of perfect transparency in the cornea and lens, and fluorescence of both. A strong light concentrated on the cornea and lens will show each to be less clear than the aqueous between them. Fluorescence is the property that some substances have of becoming faintly luminous from blue or violet light. The bluish tint of a solution of quinine in water is an example of fluorescence. A blue light thrown into the eye shows the same haziness in the cornea and lens, and the phenomenon is supposed to be due to the presence of quinine or some similar substance in these structures. These parts of the eye are therefore inferior to the clear and perfectly transparent lenses used by the optician in the manufacture of optical instruments.

C.

b. Spherical aberration, due to lack of correspondence of the axes of the cornea and lens, to the lack of symmetry in the former and the peculiar structure of the latter. This constitutes a slight astigmatism, the nature of which is noticed elsewhere. Achromatism or chronic dispersion of rays. The solar rays being made up of the different colors of the spectrum, and each color being refracted in a different degree by the same medium, they are not united by it in a single focus. Look at a street lamp at a distance through a violet-colored glass. This stops the intermediate green and yellow rays, and allows the first and last rays, the violet or blue and the red, to pass into the eye. The result is that the red is focused, but the violet. and the blue are seen in a broad halo around the red gas-light. The reason this defect is not oftener remarked is that the intermediate rays of the spectrum being brighter, the less luminous red and blue are scarcely noticed beside the intense images of the others. Optical instruments are free from this defect.

d. Slight color-blindness is common to all eyes. The eccentric portion of the retina does not perceive red as soon as other colors. If we test the field of vision as described on page 14,

we shall find that the color of a red object is not recognizable as far away as the outline of it. The eye also fails to distinguish a difference between a white produced by the union of scarlet and bluish-green light and a white produced by a yellowish-green and violet; yet the first comes out black in a photograph, the latter very bright.

e. The distinct part of the field of vision is very small; the entire field of vision of an optical instrument is very limited in extent, but distinct in every part.

f. Muscæ volitantes. These are noticed elsewhere.

g. The blind spot in the retina, due to the space occupied by the entrance of the optic nerve. Make a small cross on a sheet of white paper, and three inches to the right make a black dot. Shut the left eye, and holding the paper at arm's length, fix the right eye on the cross; on bringing the paper gradually nearer, it will be found that at about eleven inches from the eye the dot will not be seen. The blind spot is sufficiently large to hide the face of a man at six or seven feet.

h. There are also gaps in the field of vision caused by the blood vessels of the retina. These vessels running in front cast a shadow on the layer of rods and cones which lies farther back. The splits in the visual field may be recognized by looking at the sky through a delicate pin-hole in a card, moving the latter from side to side at the time.

i. The yellow spot, the most sensitive point of the retina, is by virtue of its yellow tint unable to recognize weak blue light. The smaller stars are seen better by astronomers if they look slightly at one side rather than directly towards them.

This formidable array of common optical defects is unnoticed by us, chiefly because, having two eyes, one makes up for the temporary visual disturbance in the other; even with one eye these defects are rarely noticed, owing to the great mobility of the eye and its continuous change in direction, and to the fact that the imperfections are mostly away from the centre of the field of vision. Habit, inattention, experience, the power of accommodation, may also be given as reasons why our natural visual defects are unobserved. Nevertheless, these optical defects do exist in all eyes; and, as Professor Helmholtz

observes, if an optician offered for sale an instrument with these defects, one would be justified in refusing to buy it.

DERMATOLOGICAL CASES. - CICUTA VIROSA.

C. WESSELHOEFT, M.D.

MODERN dermatology appears to consider the human cutis as something quite distinct from the rest of the body, or as an illmade garment, which ought to be removed if possible, or, at least, scoured and cleansed; it teaches that affections of the cutis are quite disconnected with other parts of the body, and of no influence upon them. Skin diseases happen to be visible and accessible externally. The natural inclination of the laity, as well as of the profession, is to treat visible, tangible diseases. locally." The laity follows conclusions of reason uninstructed in medicine; physicians do not like to encounter the arguments of the people, and, besides, must have an hypothesis to suit their practice; the consequence is "local treatment" of every diseased organ that human skill can possibly reach or approach through one of the apertures of the body. No organ, however well placed and protected by nature against such encroachments, is secure. If deranged, it will be visited in its seclusion by some insinuating probe, armed with a tiny blade, hook, or point, perchance bearing some corroding or drying medicament. When the cavities of the brain are reached and touched with caustic, when the valves of the heart are trimmed and clipped, then shall medical science have reached the zenith of its ambition. Meanwhile the dominant branches of the profession will have to rest content with the easier feats of touching only accessible parts.

Skin-pathology is perfected; the nicest of distinctions made between various classes of skin disease. Thousands of eager learners are instructed and drilled in hair-breadth distinctions between herpes, eczema, impetigo. Entire hospitals are devoted to their study; and when we seek for the end and object, treatment, it amounts to a little soap and water, and lead-and-zinc

ointment, while for numerous other metals and vegetable medicines we find no definite indications.

As long as such substances are to be employed only in large quantities, their external application is preferable, and, indeed, the only possible one. Diagnosis and treatment are planned and carried out with never-changing routine. Results, in the form of speedy, gentle, and permanent cures, are very rare under that treatment. To say that such local treatment is never followed by deleterious results, is absolutely untrue; for any physician inclined to take the trouble to inquire far enough back into the history of cases of chronic disease, will find that a large percentage can be dated to the time when some severe acute or chronic skin-disease was cured by local applications.

Nov. 1, 1873, Mr. T., æt. twenty, generally of healthy appearance, had, for about six months, a gradually-increasing eruption upon his chin, extending to both sides over the parts occupied by the beard, which he kept closely shaved, thereby removing the characteristic exudation, and obliterating the vesicles or pustules. The skin was red, shining, and swollen; the sensation connected with the eruption was burning. I advised the patient to let his beard grow, and not to disturb the eruption, in order to allow me to recognize it. Meantime he had a few doses of Ars. 20.

When next the young man presented himself, his beard of ten days' growth was matted together with a yellowish-white crust, mostly dry. This had been preceded by vesicles which exuded the fluid, subsequently forming into scabs just described. Ars. had been of no benefit. Cicuta was the next remedy. It was prescribed in the 6th cent. dil., of which one drop was dissolved in one half goblet of water, and a tablespoonful taken every five hours, beginning Nov. 29. Dec. 14 the eruption was reduced by one half, and inflammation and swelling had entirely disappeared. Prescribed three more doses of Cicuta. In another fortnight the chin presented a healthy appearance and remained so.

Jan. 5, 1875. Mr. J. E. M., blonde, hair moist, oily skin, with comedones upon cheeks and nose, of hypochondriacal disposition, subject to dyspepsia and vertigo, came to be relieved

of a scaly, moist, itching eruption upon the crown of his head, among his moist and naturally oily hair. Sulphur 81 and Graphites 3d trit, were given till Jan. 27, when, in addition to the eruption upon the scalp, there appeared numerous hard nodes upon his chin throughout his beard. These nodes gave birth to a crop of vesicles, which soon filled the beard with yellow crusts, matting the hair together, and accompanied with burning and itching. On Feb. 7 prescribed Cicuta 30, four doses, one each night. Feb. 16, very slight improvement, if any; same prescription. Feb. 24, stationary; prescribed Cicuta 3d, four doses,—one powder at a time to be dissolved in one half goblet of water, and a tablespoonful to be taken every five hours.

March 25 the chin was quite well, slight signs of humor still on the scalp. No more medicine was given; and on March 17 the patient was cured of his eruption.

The following is a much more interesting case than the preceding one:

Aug. 25, 1875. Mr. C., æt. sixty, of strong frame and good health generally, presented the following symptoms: For one year he had been troubled by a humor upon his chin, and extending through the bearded portion of his face. There was visible only shining redness of the skin, which was somewhat swollen. The sensation connected with the eruption was "itching beyond description, like a thousand furies," especially at night in bed. He tore his flesh in his sleep.

Not having seen the eruption in its undisturbed state, and in view of the redness, swelling, and itching, I prescribed Rhus 3d in water, a teaspoonful every three hours, but requested the patient to let his beard grow, and to apply no soap to his face, but to wash only in warm water. In the course of the year relief had been sought at the hands of other physicians, who applied the now favorite and fashionable benzoated zinc ointment, upon which the patient's face became smooth and clear; every trace of the eruption disappeared; or if a vesicle or pustule became visible, a little of the ointment invariably caused it to vanish from sight. But the patient's legs became heavy and his breath short, which condition lasted until the humor reappeared upon his face, and until it oozed much and itched