What is a substance, present in the protoplasm of the retinal epithelium cells, and resembling, if not identical with, the substance (myelin) forming the medullary sheaths of nerve fibers called?

myeloidin — A substance, present in the protoplasm of the retinal epithelium cells, and resembling, if not identical with, the substance (myelin) forming the medullary sheaths of nerve fibers. (Webster's 1913.)

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