. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 350 CHARLES E. JENNER AND WILLIAM L. ENGELS. L J I L L I L J I I L J l 1 1 HOURS \ 6 20 24 FIGURE 1. Schematic diagram of light schedules per 24 hours. A = long-day control; B = short-day control; C = "interrupted night." Total number of light hours in C the same as in B, but through interruption of darkness in C, periods of continuous darkness are one hour less than in A. of metamorphosis, although there were many small bundles of metamorphosed sperm in each tubule section. In the testes of the remaining two exp

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. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 350 CHARLES E. JENNER AND WILLIAM L. ENGELS. L_J I L _L_I L J I I L J__l 1 1 HOURS \ 6 20 24 FIGURE 1. Schematic diagram of light schedules per 24 hours. A = long-day control; B = short-day control; C = "interrupted night." Total number of light hours in C the same as in B, but through interruption of darkness in C, periods of continuous darkness are one hour less than in A. of metamorphosis, although there were many small bundles of metamorphosed sperm in each tubule section. In the testes of the remaining two experimental birds the first maturation division was under way. Most of the j uncos field-trapped and sacrificed at about the termination of the experiment were in spermatogenic states comparable to those attained by our short- day controls, group B. Only one of nine had reached the stage of initiation of spermatocyte division. That one is thus similar to the least developed of our ex- perimental birds of. group C. At this time, day lengths were approaching 12 hours (sunrise-sunset), and these outside birds had been exposed, for almost four weeks, to day lengths exceeding the 10 hours allowed our experimental and short-day con- trol birds. White-throated sparrows (Zonotnchia albicollis). (Tables III and IV.) The results, at first glance, may not appear to be as convincing as in the case of the juncos. t B / CM.. 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 work.. Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983. Woods Hole, Mass. : Marine Biological Laboratory

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