NATURAL HISTORY OF AMERICAN LOBSTER. 295 



is outlined on the tenth day and well formed on the fourteenth, are found in winter; 

 when segmented eggs are taken in November, and unsegmented eggs in February, it is 

 evident that the production of fall and winter eggs is not a unique occurrence in this 

 animal. 



At the western end of Vineyard Sound and in the region about Woods Hole the 

 greater number of spawners lay eggs during the latter part of July and the first half 

 of August. The summer spawning for each year lasts about 6 weeks, and fluctuates 

 from year to year backward and forward through an interval of about a fortnight. 

 This variation in the time of egg laying is not remarkable, since the period of growth of 

 the ovarian ova extends over 2 years. Any disturbance of the vital conditions of an 

 adult female during this period would be likely to affect the time of spawning. The 

 spawning season in the middle and eastern districts of Maine is about 2 weeks later 

 than in Vineyard Sound. In 1893, 71 per cent of eggs examined from the coast of 

 Maine were extruded during the first half of August. 



According to the testimony of various observers, the eggs of the European lobster 

 are generally laid and hatched from July 15 to August 31, in the northerly parts of its 

 range, including Scotland, the west coast of Norway, and Helgoland. Larvae may 

 exceptionally appear, however, at the end of June, or even as late as the first part of 

 October. In the Skager Rack and Cattegat, at the straits of the Baltic, the hatching 

 period, at least, is about two weeks earlier (see no. 303), while in the English Channel, 

 at Plymouth, Allen found that the old eggs were hatched chiefly in May and June, and 

 the new ones laid chiefly in August. 



FREQUENCY OF SPAWNING. 



The conclusion reached in 1895 that the American lobster as a rule lays her eg gs 

 but once in 9. YP'^''s hav ing been questioned, the subject was again taken up in 1902, 

 and more conclusive evidence of the truth of this general statement was given. 



It was suggested that "the best way to test the question by experiment would be 

 to take a female which had recently hatched a brood and keep her alive until the fol- 

 lowing summer, when the next batch of eggs would be due, in case the spawning period 

 is a biennial one." I attempted to try this experiment when, on June 19, 1900, Mr. 

 Vinal Edwards, acting under my direction, through the U. S. Fish Commission, placed 

 in a floating car at Woods Hole 36 lobsters from which the old light eggs, when close to 

 the hatching point, were removed to the propagating boxes. I wished to ascertain 

 three things: (i) Whether any eggs were extruded in the fall, which, according to the 

 idea of an annual breeding season, ought to occur; (2) what changes took place in the 

 ovary during the entire period from summer to summer; and (3) how many lobsters 

 among those which might survive would lay eggs in the following season, one year from 

 date. 



In order to follow the behavior of the ovary I directed that at the beginning of 

 each month one of the lobsters should be killed and its ovaries preserved, a proceeding 

 which Scott {248), in a paper on the spawning of the European lobster, quoted in another 



