In a recent paper entitled "Extensive Medullated Nerve Fibers Associated with Choroiditis,"1 I suggested the idea that the sporadic and anomalous appearance of medullated nerve fibers in the human retina might be due to the abnormal presence of one of the types of glial cells, namely, the oligodendroglia. This view was advanced because of the increasing tendency to regard the oligodendroglia as the element having to do with the secretion of myelin.
In the optic nerve, as in the central nervous system, three types of neuroglia occur, namely, the astrocytes, the microglia and the oligodendroglia. The astroglia, with its two types, protoplasmic and fibrous, are found throughout the nervous system. This type of neuroglia is characterized by the fact that the cells have some prolongations, the ends of which are applied against the walls of the small vessels. The microglia, in all probability mesodermic in origin, are