Notwithstanding the small number of these cases we may conclude from them, that homonymous diplopia in typical convergent squint (not paralytic) can only be corrected occasionally by one-sided tenotomy when the deviation is slight. As a rule it is necessary to distribute the operation between the eyes. A result seems attainable by means of simple tenotomy on both sides, which is expressed by prism 20° in the trial of convergence. In future cases it would be desirable to determine during correction of the anomalies of refraction (1) the weakest prism which is able to unite the double images at about 5 m. distant (without red glass); (2) the distance at which the double images stand apart from one another during the trial of convergence with prisms deviating in a vertical direction; and (3) the prism which brings the double images immediately above one another in the case of objects about 5 m. off. Next to the cases above discussed stand those where convergent squint remains after paralysis of the abducens; at the same time slightly defective mobility and a distinct moving apart of the double images towards the affected side can usually be detected. In a few such cases I could restrict myself to tenotomy of the internal rectus of the affected eye, but in those cases which I was able to attend to more particularly, double tenotomy was necessary, and did not always suffice. Here also the advancement of the external rectus is suitably applied, which I should like to illustrate by means of a few examples. CASE 49.--Mr. B--, æt. 20, was seized by paralysis of the abducens of the right eye in November, 1877. In April, 1878, convergent squint was still present, and as it continued patient decided on an operation in February, 1879. Both eyes are emmetropic and possess full visual acuteness. Immediately before the operation the double images were united at 4 to 5 m. in the horizontal plane by a prism of 39°; towards the right their deviation rather increased. The measurable deviation amounted to 4 mm. in the right eye, the secondary deviation of the left to 5 mm. In order to proceed carefully, I confined myself at first to tenotomy of the internal rectus of the right eye. After the space of a week single vision was present at the distance of 1 metre in the middle line and at the height of the eyes; at about 5 m. homonymous double images corrected by prism 12°, together with slight difference in height (= prism 4°, base upwards before the right eye). The area of double vision extended from the limit of the right visual field to about 20° the other side of the middle line.