. The biology of the frog. Frogs. 346 THE BIOLOGY OF THE FROG that of the rods, runs out into a fiber which enters the outer reticular layer. The cones vary in size and form, as many as three varieties being distinguished (M. Schultze, van Genderen Stort). Some of these are movable, expanding in. Fig. 109.—Sections through the outer part of the frog's retina with its pigmented epithelium. The figure on the left is taken from a frog which had been exposed to daylight for five hours. The proc- esses of the three outer pigment cells extend inward to the external limiting membrane, and the pigment
. The biology of the frog. Frogs. 346 THE BIOLOGY OF THE FROG that of the rods, runs out into a fiber which enters the outer reticular layer. The cones vary in size and form, as many as three varieties being distinguished (M. Schultze, van Genderen Stort). Some of these are movable, expanding in. Fig. 109.—Sections through the outer part of the frog's retina with its pigmented epithelium. The figure on the left is taken from a frog which had been exposed to daylight for five hours. The proc- esses of the three outer pigment cells extend inward to the external limiting membrane, and the pigment they contain has streamed in- ward, surrounding the rods and cones nearly to their base. The cones are strongly retracted, so that their outer segments lie near the limiting membrane. The figure on the right is taken from a frog that had been kept for forty-eight hours in darkness. The pig- ment in the processes of the pigment cells is drawn back toward the center of the cells, and the cones are extended outward between the rods. The nuclei of the rod and cone cells are shown below the limiting membrane. (From Gaupp, after Van Genderen Stort.) the dark until they may reach the periphery, and contract- ing under the influence of light. Ordinarily most of the cones do not reach the outer surface of the retina. The retina is marked by a thickening or papilla where the optic nerve enters. Above this papilla there extends. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Holmes, Samuel J. (Samuel Jackson), 1868-. New York : The Macmillan company
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Keywords: ., bookauthorholmessamueljsamuelja, bookcentury1900, bookdecade1920
