ABSTRACT
About two years ago, the writer made a study of the retinal pigment epithelium of twenty-two English frogs which had been subjected to various experimental conditions and found that the dispositions of the pigment granules could not be explained adequately in terms of the oft-described migration which is believed to take place during light- and dark-adaptation of the eye. The results were anomalous, in so far as the amount of pigment present under certain conditions seemed to be greater than at other times.
This Hanovia lamp was obtained by means of a grant from the Dixon Fund.
Krause (quoted by Gaupp) states that the rods of the frog are 0· 081 mm. long. The writer’s measurements extend from the external limiting membrane to the free terminations of the rods.
