. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 204 YASUO SUGIURA siderable amount of eggs or sperm can be obtained by a single discharge ranging from 5 to 35 seconds. Over-stimulation lasting more than 30 seconds should be avoided, since this causes prolonged contraction or occasionally even death. The time required for recovery from the stimulation-induced contraction varied widely, from several minutes to several hours. Intermittent stimulations of very short duration seem to act excessively: after three stimulations of 6 seconds each, given 3-5 minutes apart, although
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 204 YASUO SUGIURA siderable amount of eggs or sperm can be obtained by a single discharge ranging from 5 to 35 seconds. Over-stimulation lasting more than 30 seconds should be avoided, since this causes prolonged contraction or occasionally even death. The time required for recovery from the stimulation-induced contraction varied widely, from several minutes to several hours. Intermittent stimulations of very short duration seem to act excessively: after three stimulations of 6 seconds each, given 3-5 minutes apart, although all the animals discharged, 20% of them failed to recover from FIGURE 1. Urcchis iinicinctits spawning under electrical stimulation. If due caution is paid to the duration of, and the intervals between, stimulations, one to two stimulations a day can be given for 6 consecutive days to animals fully charged with reproductive cells. In one case, animals which had been kept for 11 days in captivity and made to spawn nine times, still discharged eggs which developed on insemination, to normal trochophores. II. Hermaphroditic i\f \Hlus cdulis MATERIALS AND METHODS Mytiliis cdulis is normally dioecious, and hermaphroditic individuals can be found only very rarely. Among some 400 individuals examined by the author at. 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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