264 



SCIENCE. 



[N. S. Vol. I. No. 10. 



this case egg-layiug follows close upon 

 copulation. Sometimes a female is impreg- 

 nated immediately after the old eggs are 

 hatched and before the molt occm-s. A 

 second copulation is then necessarjf for the 

 fertilization of the eggs. Occasionally the 

 seminal receptacle of a lobster is found 

 loaded with sperm a year before the eggs 

 are due. 



Laying of Eggs. — Much confusion has sur- 

 rounded this subject because of the lack of 

 continuous observation throughout the 

 year. The facts seem to be as follows : 

 The majoritj^ of lobsters capable of spa'WTi- 

 ing lay eggs in July and August. About 

 20 to 25 % extrude their eggs at other times, 

 it may be in the fall, winter or spring. Dur- 

 ing a period of seven consecutive months 

 five traps were kept set in the harbor of 

 Wood's HoU, Mass., December 1st, 1893, to 

 June 30th, 1894, and visited daily. In all 

 168 egg-lobsters were taken; 44, or 25.6 % 

 of the number, bore eggs which had been 

 laid in the fall and winter. 



I have tabulated 51 lobsters coming from 

 different parts of the coast of Maine, having 

 external eggs which had been laid out of 

 the usual season of July and August. In 

 one case at Matinicus Id., Maine, February 

 4th, the eggs had been extruded but a few 

 hours, and the yolk was unsegmented. 

 Another from York Id., Maine, November 

 15th, had eggs in a late state of segmen- 

 tation of the yolk. Still another from 

 Brimstone Id., Maine, January 27th, had 

 eggs in the nauplius stage . At Wood 's Holl , 

 in 1889 to 1893, the recorded observations 

 (over 300 in all) show that the greatest num- 

 ber of eggs are laid in the last two weeks of 



ster, and the habits of the larviS aud young diu-ing 

 their period of immaturity. Tlie history of the lan'a 

 and the structure and development of the reproduc- 

 tive organs -nill be fully described, and the develop- 

 ment of the embrj'o ^vill also be reviewed. The work 

 is illustrated by 54 full-page plates, many of whicli 

 are executed in colors or reproduced from jilioto- 

 graphs, and by 40 figures in the text. 



July, the whole period lasting from June 

 16th to August 31st. Data ft-oni the Maine 

 coast (129 observations) indicate that the 

 greatest number spawn in the first two 

 weeks of August. 



The spawning period of lobsters in the 

 extreme north is said to last from July 20th 

 to August 20th in Newfoundland. July 

 and August are the months commonly as- 

 signed for the spawning in Prince Edward 

 Island. 



Number of Eggs Laid and Law of Produc- 

 tion. — In the course of the work of lobster- 

 hatching at the Station of the United 

 States Fish Commission at Wood's Holl, 

 it becomes necessary to remove the eggs 

 from a large number of lobsters. These 

 are carefully measured and the number de- 

 duced by simple calculation. I have tabu- 

 lated the number of eggs laid in 4,645 lob- 

 sters measuring from 8 to 19 inches. In 

 examining the column of averages one is 

 struck hy the fact that a ten-inch lobster 

 bears twice as manj' eggs as one eight inches 

 long ; that a twelve-inch lobster bears twice 

 as manj^ as one ten inches long. It is there- 

 fore suggested that in early j-ears of sex- 

 ual vigor there is a general law of fecun- 

 dity which may be thus formulated ; the 

 number of eggs produced by female lob- 

 sters at each reproductive period varies in 

 a geometrical series ; while the lengths of 

 lobsters producing these eggs varj- in an 

 arithmetical series. If such a law prevails 

 we would have the following : 



Series of lengths in inches: 



(1) (2) (3) (4) (5) (6) 

 8 : 10 : 12 : 14 : 16 : 18 



Series of eggs : 

 5,000 : 10,000 : 20,000 : 40,000 : 80,000 : 



160,000. 



An examination of the table shows how 

 closely the first four terms of this series are 

 represented in nature, aud that when the 

 14-16-inch limit is reached there is a de- 

 cline in sexual activitj\ Yet the largest 



