S. Ramon Cajal. Nouvelles contributions à l’étude histologique de la rétine. Journal de l’Anatomie et de la Physiologie. XXXII année, 1896, № 5. Septembre—octobre. P. p. 481—543

In the development of rods and cones, the author notes 4 common and other main periods: the embryonic period, the period of unipolarity, the period of bipolarity and the period of the young state. The first period corresponds to the period of the germinal bodies of His and, to some extent, the period of mitosis, described, for example, by Koganeem and Shevich. The shape of the visual cells at this time is irregular, spherical. In newborn cats, rabbits and dogs, all these cells, apparently, have already passed this period, at least it is impossible to see mitosis at this time. In the second period, located in the beginning along the neighborhood with m. limit. externa, the cell stretches out and gives a long outgrowth, the end of which is the cell itself, gradually descending downward to the point at which it should be in adulthood. The body is ellipsoidal with a vertically standing long axis; but sometimes this form is changed through compression by the neighboring elements.