. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 216 F. A. BROWN, JR., M. N. HINES AND M. FINGERMAN Since a change from darkness to light is evidently an adequate stimulus for the re- lease of the light-adapting hormone it seemed reasonable that a change from light to darkness would be a normal stimulus causing secretion of a dark-adapting hor- mone. In order to test this possibility an experiment was designed in which re- sponses to a brief light flash were compared following different durations of dark periods. Palaemonetes were taken at random from the stock supply and
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 216 F. A. BROWN, JR., M. N. HINES AND M. FINGERMAN Since a change from darkness to light is evidently an adequate stimulus for the re- lease of the light-adapting hormone it seemed reasonable that a change from light to darkness would be a normal stimulus causing secretion of a dark-adapting hor- mone. In order to test this possibility an experiment was designed in which re- sponses to a brief light flash were compared following different durations of dark periods. Palaemonetes were taken at random from the stock supply and distributed among six groups of five white enamelled pans. Approximately 12 animals were put into each pan. The first group of animals constituted the control group. Distal pig- CONTROL I5MIN. DARK 40 MIN. DARK 60 MIN. DARK 120 MIN. DARK 240 MIN. DARK. 20 180 240 TIME IN MINUTES 300 360 FIGURE 2. Responses of the distal pigment to a one-minute, 250 light flash after different intervals in darkness. ment indices of 10 animals from one of the pans of this group were determined at 9 and the remaining containers were placed immediately in darkness. The course of dark-adaptation was followed by removing a pan from darkness and de- termining distal pigment indices of 10 animals after 15, 30, 60 and 120 minutes. The remaining five groups of pans were also placed in darkness at approximately 9 At 15 minutes one group of five pans was subjected to a one-minute, 250 , flash of light. Immediately following the flash the distal pigment indices of 10 animals from one pan were determined. The course of dark-adaptation of this group was followed by determining distal pigment indices of 10 animals after 30, 60, 120, and 180 minutes. Similarly, of the other groups, one was dark-. 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
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