. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 270 L. H. KLEINHOLZ AND F. G. \V. KNOWLES takes up its position in response to the light ; 3 On examin- ing sections of retinas in any particular stage of light-adaptation, it is seen (Figs. 4-7) that the pigment in the dorsal portion of the eye has always undergone a greater amount of migration (toward the basement membrane) than that in the ventral portion. But since migration of the distal pigment is under hormonal control (Kleinholz, 1936), the reason for the unequal position of this pigment is not clear.
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 270 L. H. KLEINHOLZ AND F. G. \V. KNOWLES takes up its position in response to the light ; 3 On examin- ing sections of retinas in any particular stage of light-adaptation, it is seen (Figs. 4-7) that the pigment in the dorsal portion of the eye has always undergone a greater amount of migration (toward the basement membrane) than that in the ventral portion. But since migration of the distal pigment is under hormonal control (Kleinholz, 1936), the reason for the unequal position of this pigment is not clear. If the variation in position of the pigment of the dorsal and ventral regions of the retina is constant under all conditions of illumination, the inequality could be attributed to greater sensitivity of the pigment cells in the dorsal portion of the retina to the eye-stalk hormone. If, on tr o 0. tr ci Q_ o O a. 350 Z5O 150. 2O 40 1000 60 FIG. 2. The relation between position of the distal retinal pigment and the ratio, incident light reflected light the other hand, this difference could be reversed by changing the method of illumination, the above explanation would not be valid; in such an event the greater amount of migration in the portion of the eye most strongly illuminated (toward the source of light) might be due to an additional direct effect of light on those cells. This point was 3 Butcher and Adelmann (1937) reported, however, that illumination of Fundulus heteroclitus from below against white and against black backgrounds did not result in the same color changes evoked in illumination from above, therefore implying a fixed structural difference in the retina. This difference apparently lies in the structure and distribution of the rods and cones in the dorsal and ventral portions of the retina (Butcher, 1937).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of th
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
