The Spawning of Lingula
摘要
1) The breeding season of Lingula unguis lasts in Misaki from the middle of July to the end of August, and there is the peek around the first half of August. 2) Germ-cells are emitted through the median funnel of setae at the anterior margin of shells, and this takes place rather powerfully in a stream looking like a small fountain. Generally speaking, sperm-emission continues somewhat longer than the egg-emission, and the largest emission of sperm witnessed continued for 2 hours and 55 minutes, while the egg-emission was for 2 hours. 3) Among the factors in shedding, time of day was considered to be the most important. Sheddings occurred quite regularly twice a day at least during the middle part of the breeding season, the first one taking place in the morning soon after sunrise and the second one in the evening soon after sunset. But, the problem whether this persistent tendency was inherent in the animals, or it was a result affected by the change of light condition was not settled. There were evidences that both might be true. 4) When shedding was initiated by some individuals, it was generally followed succes\nsively by other individuals in the same vessel. This fact suggested that possibilies of some effect in the shedding of some individuals that might induce other individuals to shed. Some experiments were tried, but no experimental evidence of it was obtained. 5) Aggregation of animals seemed to provide a certain condition that might be important for the animals to shed, since the frequency of shedding was greatly reduced in the vessel in which only a small number of individuals were cultured.