Like all other phases of the muscle problem, that of which I treat in this paper can scarcely be said to be solved; indeed, it may well be doubted if a distinct discrimination is always made between this variety of strabismus and concomitant squint. It is not easy in infants and young children to detect a limitation in the movement of an eye, which is the usual diagnostic point of difference between congenital and concomitant squints, though it will be remembered that while in concomitant squint the deviation of the ocular axes persists as the eyes are moved through the different meridians of the field of fixation, the degree of the deviation remains constant, and the angle of the squint is always the same, whereas in congenital squint the degree of the deviation and the angle of the squint vary according as the eye with the defective muscle or muscles