NATURAIy HISTORY OF AMERICAN EOBSTER. 
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. J05), 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 eggs 
but once in 2 years having 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 
