. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 190 ANTHONY E. GANAROS. FIGURE 1. Egg case of I', cincrca with five ova. X 10. At ° C. the ova required 66 days to reach the early veliger stage, and 84 days before the shelled veligers appeared. At ° C. no development occurred during the 54 days. At the end of those periods both the ° C. and ° C. groups were placed in water of ° C. to determine whether they would develop under the new temperature condition, regardless of their previous treatment. Only 65 per cent of the egg cases kept originally at ° C
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 190 ANTHONY E. GANAROS. FIGURE 1. Egg case of I', cincrca with five ova. X 10. At ° C. the ova required 66 days to reach the early veliger stage, and 84 days before the shelled veligers appeared. At ° C. no development occurred during the 54 days. At the end of those periods both the ° C. and ° C. groups were placed in water of ° C. to determine whether they would develop under the new temperature condition, regardless of their previous treatment. Only 65 per cent of the egg cases kept originally at ° C. produced conchs, while no development occurred in the former group at ° C. Since the egg cases at ° C. were apparently adversely affected before being placed at ° C., it may be inferred that temperatures at ° C. and lower not only arrested development, but killed the eggs after a prolonged period of exposure. Our results indicated that the optimum temperature for drill development was TABLE I Number of days for ova to develop to various stages at constant temperatures and the percentage of egg cases producing young conchs Temperatures ° C. ° C. ° C. ° C. ° C. ° C. Early veliger 54* 66 10 7 4 2 Shelled veliger — 84** 25 15 7 7 Protoconch — — 30 22 22 22 Release of young conchs — — 56-78 30-43 22-38 22-38 Percentage of egg cases producing young conchs o% 65% 90% 100% 95% 90% * No development. ** Placed in water of ° 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 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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