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 ophthalmoscopic examination. Berlin records a case in an old horse and others in young cats, and Möller other cases in dogs. Treatment is manifestly hopeless.