432 BENJAMIN H. GRAVE. 



began until alter the first quarter when they suddenly fell off not to be fully revived 

 until somewhat after full moon. Then followed a week of heavy spawning until 

 new moon. 



Shortly after the first quarter in August the heaviest spawning of the year 

 began and continued until the approach of the next new moon or from August 7 

 to August 29. Then came the usual late season, temporary cessation of spawning 

 which presumably revived somewhat at the September full moon. 



It is unfortunate that these experiments could not have begun by the middle of 

 June and continued until the middle of September. The experience of several 

 years leads one to believe that spawning began at full moon in June and reached 

 maximum late in June. The variations in spawning activity under laboratory 

 conditions show that the production of the gametes is greatest around full moon 

 and least around the first quarter. These results are shown regularly except at 

 the height of the breeding season when it may be masked by the rapidity of egg 

 production. 



SPAWNING EXPERIMENTS. 1926. 



CUMINGIA TELLINOIDES. 



Table No. III. 



The following table of experiments shows the duration of the spawning season 

 and variations in spawning activity during the lunar cycle. From fifteen to 

 twenty-five individuals were used in each experiment. They were isolated in 

 stender dishes containing enough water .to cover them fully. Spawning usually 

 occurs within an hour. Collections were always made at low tide. 

 I. 3/1. No eggs and no spermatozoa. 

 II. 4/1. No eggs and no sperm. 



III. 6/1. No eggs and no sperm. (Experiment by Hugh Montgomery.) 



IV. 6/1 1. No eggs and no sperm. (Experiment by Hugh Montgomery.) 

 V. 6/15. No eggs, one male shed active spermatozoa, one fifth maximum. 



* June 18, first quarter. 



VI. 6/21. 2 females spawned, approximately 1/5 maximum. 2 males shed 

 sperm, 1/4 maximum. 8 did not spawn. 



Comment. Eggs mature, cleavage normal. Spawning season opened between 

 June 15 and June 20. 



* June 25, full moon. 



VII. 7/1. 6 females spawned, 1/4 to 1/3 maximum. 7 males shed sperm, 

 1/3 to 1/2 maximum. 2 did not spawn. 



* July 2, third quarter. 



VIII. 7/6. 9 females spawned rather abundantly, 1/2 to 3/4 maximum. 12 

 males shed sperm, n heavy, i light. 2 did not spawn. 



* July Q, new moon. 



IX. 7/15. 2 females spawned, 1/2 to 2/3 maximum. 12 males shed sperm, 

 10 medium, 2 light. 12 did not spawn. 



Comment. Light spawning, and many failed to spawn. 



* July 17, first quarter. 



X. 7/19. 2 females spawned 1/20 maximum (very few eggs). 4 males shed 

 sperm, very light, i/io to 1/20 maximum, scarcely detectable in the 

 dish. 13 did not spawn. 



