438 Veterinary Medicine. 



vitreous and coincident softening of the suspensory ligament. 

 In either case, if the ligament is torn through in more t'han one- 

 half its circumference, the lens will hang by the remainder and 

 move on it as on a hinge so as to change its location in the dif- 

 ferent positions of the head. This is especially so where the 

 vitreous has become abnormally fluid as there is then no resist- 

 ance to the free backward movement of the lens. The writer 

 has seen the eye of a cow affected in this way, so that the cata- 

 ractous lens advances to the pupil and recedes from it as the eye 

 is moved. In other cases the dislocated lens, being attached 

 below only, drops down and virtually disappears behind the lower 

 part of the iris. In still other cases it becomes wedged into the 

 pupil, or protrudes into the anterior chamber and lies in front of 

 the pupil and iris. The semi-detached lens sooner or later be- 

 comes opaque. A cataract with contraction of the newly formed 

 tissue on the capsule and undue tension on the suspensory liga- 

 ment may, however, precede the dislocation which is then pre- 

 cipitated by some shock, as a blow, fall, sneeze, cough or emesis. 



The condition leads to an apparent increase in the depth of the 

 anterior chamber, and tremulous movement of the iris, and if il- 

 luminated the impacted condition of the lens or its changes of 

 position can be detected. If its edge is exposed it appears as a 

 black ring. 



Treatment is useless, unless it be extraction of the lens, or 

 iridectomy in suitable cases. 



PERSISTENT ARTERIA HYALOIDEA. 



In the embryo this artery occupies the central canal of the 

 vitreous and extends from the optic papilla to the posterior pole 

 of the lens. At times it persists after birth and even to mature 

 life and is then detected as a gray or dark thread on ophthal- 

 moscopic examination. Berlin records a case in an old horse and 

 others in young cats, and MoUer other cases in dogs. Treatment 

 is manifestly hopeless. 



