Interest in polarized light has increased during the past few years owing to the fact that inexpensive, large area polarizing materials have become available. A new material, which bears the trade name polaroid, is suitable for incorporation in optical systems and is, in fact, already standard equipment for use with some ophthalmoscopes. It seems appropriate, therefore, to describe and discuss at this time certain ocular phenomena that I have observed with polaroids.
The phenomena are of two types : One is produced by the lens of the eye and has previously been described in part ; the other is produced by the anterior segment of the intact eye and has not, to my knowledge, previously been noted in the literature. Both are produced by crossed polaroids and have in common the appearance of a black cross on a bright background, but as I have no right at the outset to assume that