June 11.

Left, better. Right, can see a white paper before the eye, owing to a little clearing up of the cornea at its inferior edge near the opening. Paracentesis again.

June 13. Left, improving. Right, about the same. Paracentesis.

June 16-Same; but the chemosis, which had been lessening, is now more marked above the cornea, and there appears to be a more dense infiltration of pus in that part of the cornea near it. Paracentesis. Use the hot fomentations, for fifteen minutes, only once a day.

June 18.-Right eye, less chemosis. Paracentesis.

June 20.
June 23.
June 25.
June 28.

C, No. 200.

Right, again clearing up a little. Paracentesis.
Right, cornea clearer.

Right, cornea improving slowly.

Right, better. Saw, near the eye, the large letter

June 30. - Right, saw letters No. 100 near the eye.
July 2. Improvement has ceased.
Paracentesis.

July 5. July 7. July 10.

Right eye better again.

Right, improving again.

Fomentations twice a day.

Sees letters No. 70.

Right, sees letters numbered 30 near the eye. July 14, 16. Record is the same. The patient left Boston for his home a hundred miles away. His left eye had so far recovered that with D + 1.25 he could read print No. 8 comfortably. The distinction between a suppurative process in the cornea and some forms of ulceration is by no means clear, and the above case resembled somewhat the creeping ulceration of the cornea called the serpiginous ulcer.

THE CAUSE OF MYOPIA.

Myopia is rarely congenital; often hereditary, but still oftener acquired. It is possible that hereditary predisposition to the affection may exist in those cases where it is acquired, and in which no myopic parentage can be traced.

Late researches tend to show that among school children the myopic eyes are recruited, as the process of education goes on, mostly from those of hypermetropic refraction; that in young children this form of optical defect is very common, but as time goes on and the eye is used for new objects in study, and especially if the child is not robust, the hypermetropic refraction is lost and the eye becomes myopic. This change to myopia is all the more likely to occur if there is an astigmatism also. The astigmatic eye is usually weak and diseased, especially if the astigmatism is myopic. Such eyes pass directly over from hypermetropia to myopia, without passing first into the emmetropic or normal

refraction. It is affirmed that an emmetropic eye will, in all probability, escape injury during the educational period; but comparatively few eyes can be strictly classed as such. Progressive or acquired myopia in young people may not be directly attributable, therefore, to the process of education, although education undoubtedly encourages and hastens its development in all those children whose eyes deviate from the emmetropic standard. Unfortunately, the greater number of eyes are found to be hypermetropic, and then pass easily over into the myopic.

THE OPHTHALMOSCOPE IN MEASURING AN AMETROPIA

Is difficult in practice. The accommodation of the patient must be relaxed, and if the dark room in which the examination is made be sufficiently spacious, so that the patient may fix his eyes on some distant object, this may be easy; otherwise Atropine or some other mydriatic is necessary. The observer must also relax his accommodation. Then the convex lens, beginning with the weakest that enables the observer to see the region of the macula lutea (where there is really very little to see) most distinctly, is supposed, if the defect is a hypermetropia, to give its measure. In the same way, using concave lenses, the degree of a myopia is determined. The optic disk is a definite enough object to observe, but is not available when strict accuracy is desired; as, not being at the fovea centralis, it cannot be at the same distance from the centre of the cornea. In myopia it is sometimes anterior to the macula. The same difficulties present themselves in determining the exact degree of an astigmatism. However, as an aid in determining and confirming, in connection with other tests, the existence of optical objects, the ophthalmoscope used in this way is convenient. This method of measuring optical defects is good practice for oculists, if for no other reason than that it breaks into their routine habits of diagnosis.

MIXED FORMS OF ASTHENOPIA.

Muscular asthenopia is most frequently due to myopic refraction, and accommodative asthenopia to hypermetropic refraction, while in astigmatism we have either or both forms. In emmetropic eyes an asthenopia is usually accommodative, but not unfrequently it is both accommodative and muscular. In those cases where no optical defect is apparent, the cause is often in a lack of proper co-ordination between accommodation and convergence. Usually, in such eyes, if we aid accommodation by weak convex glasses, we diminish the effort of convergence at the same time, as the two acts are consentaneous, especially in emmetropic eyes. If this is not sufficient to relieve the discomfort after a trial of a

week or two, we may lessen the effort of convergence by trying prisms of 2° base inwards. These help the overtaxed recti interni in turning the eyes inward. The prisms may be combined with the convex lenses or used separately. Of course a mixed form of astigmatism is oftener met with where the refraction of the eye is not emmetropic. It may occur in anisometropia, - that is, in unequal refractive power of the two eyes. Suppose one eye slightly myopic, the other slightly hypermetropic: there would be no binocular vision, in the strict sense of the term; and the frequent tension and relaxation of accommodation, and possibly of the convergence also, would be likely to overwork the apparatus of adjustment. The indication here would be, probably, to adjust a weak convex lens to the hypermetropic eye, so that in reading, this eye would be made slightly myopic like its fellow. When the difference in the refraction of the two eyes is very considerable, this course may not be advisable, and we must be content to put the one reading eye into the most favoring condition, approximating the other as nearly as practicable to the same refraction. Prisms may of course be used, if necessary, bases outward. Sometimes, but not often, in hypermetropia we find the recti externi weak. Prisms of 2° base outward would relieve the external, and put more work on the internal recti. The same result may be reached, though less in degree, by decentring the glasses; that is, if we wish the effect of prisms base outward in hypermetropia, we order a wider separation between the two glasses, so that the centre of each lens shall fall a little outside the centre of each pupil. These glasses relieve the overtaxed accommodation and the recti externi at the same time. By having them set nearer, that is, separated less widely, we may produce the effect of prisms base inward, and relieve to a certain extent the recti interni. In myopia, if we wish to slightly relieve the overworked muscles of convergence, we have the concave lenses separated so that their centres are just outside the two pupils.

Astigmatism uncorrected by glasses may, of course, give rise to accommodative or a mixed form of asthenopia.

Indeed, in connection with myopia it is, as is well known, a great factor in the production of pain and discomfort, and perhaps the same may be said of its influence in the asthenopia so common with hypermetropic refraction. Late investigations appear to show, further, that astigmatism, myopic and hypermetropic, uncorrected, threatens the integrity of the eye. Distinct lesions of the fundus of the globe are most frequent in myopic astigmatism. Next in frequency, a hypermetropic astigmatism is accredited with the production of a posterior choroiditis and atrophy around the disk of the optic nerve, such as is observed in myopia. Eyes of this class are, as before remarked, those that pass over and

become myopic, and usually progressively myopic. In view of these facts, it may be said that astigmatism is, in early life, a most dangerous optical defect, and that its subjects, like those that are myopic, should be most carefully guarded during the educational period. The later the earnest study from books begins, in the life of children with optical defects, the less probability of harm to the eyes. If school life, or protracted reading, writing, and drawing were never begun before the age of eight or ten, diseases of the eye or impaired vision would notably decrease.

A CASE OF PLACENTA PRÆVIA WITH TWINS. BY EDWARD M. CURRIER, M. D. (B. U. s. M., '81), PRAGUE, Austria.

ON the 12th of October, Marie Kozah, a Bohemian peasant woman, aged thirty-three, presented herself at the Lying-in Hospital, at Prague, Austria, desiring to be admitted. She stated that this was her fourth pregnancy, and that the former three were prefectly normal, going the full term, and living children being born in each case. She said that her last menstruation was on the 1st of March, so that she had nearly eight weeks to continue before the full expiration of pregnancy.

At the time she presented herself she was in a somewhat anæmic state, slightly pale, pulse 108. The abdomen was distended as far up as the ensiform appendix. She came to the hospital because about an hour before she had had a sudden. hemorrhage, which frightened her, as it had never occurred in any of her former pregnancies. Palpation showed that the head. was in the left iliac region, and the small parts could be felt in the right hypochondrium. The examination was hurriedly made and it was supposed that there was but one foetus. Internal examination showed that the vagina was much dilated and some blood clots were felt. The neck of the womb was still projecting into the vagina. It was very tender and the external os was sufficiently dilated to admit of the passage of two or three fingers. The cervix uteri was not yet effaced. Its channel was about five centimetres long, and the inner os was forming a contracting circle which would scarcely allow the passage of two fingers. The channel of the cervix was filled with blood clots and a globular portion of the placenta was slightly projecting. As far as the finger could reach, the inner os was covered by the placenta. The membranes were so thick that it was impossible to tear them with the fingers, so that the operator was obliged to use a uterine sound to rupture them. Then the right foot was seized with two fingers only and version easily effected by the bi-manual method

of Braxton Hicks. The extraction was made very slowly in order to dilate the inner os for the passage of the breech and head. The extraction being made, the uterus was less diminished than usual, and the presence of a second foetus was easily diagnosticated. The hemorrhage recommencing, it was necessary to deliver the woman instantly. Two fingers were again introduced into the uterus, the membranes of the second child ruptured, a foot seized, and version and extraction made in the same manner as before. Then the placenta was detached from the inner walls of the uterus and a warm water injection was made to stop further hemorrhage. The uterus contracted and no further hemorrhage followed. The children were both male. The first one delivered weighed 1,885 grammes and was 44 centimetres in length. The second weighed 1,700 grammes and was 41.I centimetres in length. The placenta weighed 800 grammes.

DIAGNOSIS OF HUMAN BLOOD-STAINS.

BY JOHN C. MORGAN, M. D., PHILADELPHIA.

DRS. J. G. RICHARDSON and J. J. Woodward, both eminent microscopists, have for several years been in (only) apparent antagonism on the question, Can human blood be positively distinguished from that of the various domestic animals? Our own microscopist, Prof. J. Edwards Smith, has taken part in this controversy in his usually interesting manner. The whole subject is reviewed - and set at rest, we may believe — in an explanatory article which may be found in the "American Journal of Microscopy" for June, 1881. The sum of the matter is, that the blood of animals usually slaughtered, owing to smallness of globules, can be microscopically diagnosed with accuracy; that of certain others, not usually slaughtered, cannot be, owing to the superior size of the globules, approximating the human very nearly indeed. Per contra, small human globules are common in anæmia.

Again, corpuscles are changed in size, by yielding their contents to, or absorbing any fluid which may be used to suspend them, unless it be carefully adjusted to prevent this. For this purpose, Dr. Richardson uses a per cent solution of common salt.

Further, when micro-photographs, like those presented by Dr. Woodward in the Hayden murder trial, are used, it is important to exclude all but the central parts of the same from comparison, since the photographic lenses are not free from spherical aberration, which enlarges the periphery of the figure, or plate. Dr. Piper.

Lastly, be it remembered that mosquitoes and other insects