Barium in the Mammalian Retina. ∗

Abstract

Ramage and Sheldon 1 discovered the existence of Ba in the chorioid of ox eyes. They believed that Ba increased in quantity with age and report that it is not present in calves' eyes in sufficient quantity to be detected by their method of flame excitation of the spectrum. Furthermore they say that Ba is not present in the chori-oids of human, sheep, pigs, horses, dogs and many sea fish. Ramage and Sheldon failed to find this element in the retina although they could detect it in the iris and the pigment of the chorioid. It is of some significance that they found Ba in the chorioids of all neat cattle beyond 3 years in age. Gerlaeh and Muller 2 examined eyes from a wide variety of animals including man and discovered Ba in the chorioid of most of them. It was not present uniformly in human chorioids and there appear to be no age peculiarities in its distribution. These writers also describe Ba in the retinae of ostrichs, rabbits, cats, cattle and in one human.

The material in the present series consisted of 19 pigs, 17 ox, 24 sheep and 12 kitten eyes. The spectrographic method used was that described by us in an earlier paper (Scott and Canaga 3 ). We used as identifying lines the 4535.5 and 4934.1 A. These lines are quite sensitive and can be definitely located with little trouble. An attempt was made to localize Ba in the tissue by separating the retina into 2 layers. Experiments showed that the retinae split easily along the internal limiting membrane giving one layer which consisted largely of nerve fibers and another which was made up of pigmented epithelium, rods and cones and their nuclei, neuroglial and bipolar cells.