THE AMERICAN LOBSTER. 
71 
twenty-one such dissections are given (Nos. 1, 4 to 10, 29 to 33, 35, 37, 38, 40, 53, 56, 
G2, 95) which illustrate the condition of the ovary before the eggs hatch, up to about 
the middle of August, or from sis to eight weeks after hatching. The ovarian eggs 
have had, in all these cases, from ten months’ to a year’s growth, this interval having 
elapsed since the last sexual period, when eggs were extruded. 
The colored drawing, fig. 138, plate 38, represents, in natural size, the ovary of a 
lobster (No. 95, table 20) four to six weeks after the hatching of its eggs. In figs. 136, 
137, and 138 I have given representations of the ovaries of the lobster as they appear 
thirty-six hours, six weeks, and one year after egg-laying. Figs. 134, 135, and 133 
show the average size and form of the ovarian eggs, drawn to the same scale, at these 
various periods. The ovarian eggs are in about the same condition of immaturity in 
figs. 133 and 135, and it would seem that immediately after egg-laying the ovary grows 
very rapidly, and then enters upon a long period of rest. In the following summer, 
when the external eggs have hatched, another period of rapid growth is experienced 
in the ovary, and at the beginning of the third summer after ovulation there is a third 
period of active growth which continues until the new ova of the next generation are 
ripe. That the spawning periods are thus two years apart is a valid inference drawn 
from the study of the anatomy of the reproductive organs. (See note, p. 152, and in 
particular the description of tig. 138, p. 246.) 
If the spawning period of the lobster is a biennial one, and if the sexes are equally 
divided, we should expect to find half of the adult females carrying eggs each year. 
In other words, one in every four mature lobsters (of both sexes) captured would carry 
external eggs. Since lobsters do not mature at a uniform period , or when of a uniform 
size, it is impossible to get perfectly accurate data upon this point. It would be 
impossible, furthermore, to trust any data, unless we could be certain that the egg- 
bearing lobsters were uniformly distributed. The facts which we have, relating to 
this point, are however, worth considering. 
In April, 1889, a number of lobster pots were set in the harbor of Woods Hole 
by Vi nal N. Edwards, and a daily record of the catch was made. A total of 3,230 
lobsters were captured, as described in table 21. About one in every seven bore eggs. 
The percentage of females with external eggs to the whole number of females taken was 
40 in April, while it dropped to 36 in May. This slight fall might or might not be owing 
to the hatching of some of the eggs, while it is evident that the drop to 9 per cent in 
June is due to this cause, by far the larger part of the eggs being hal ched in this month. 
It is seen that in the total catch of 2,657 lobsters, from December 1, 1893, to 
June 30, 1894, the sexes are very nearly equally divided, and that about one in every 
fifteen lobsters captured bore external eggs. Neither this nor the percentage of 
females with eggs to the whole number of females has any special significance, since 
both mature and immature are included. Striking out the months of May and June, 
when the eggs are mostly hatched, and eliminating the smaller lobsters, we find the 
percentage of egg-bearing lobsters 10 inches long or over to the whole number of 
females of the same length with or without eggs (that is, mature female lobsters), to be 
21.79. If the limit is taken at 9 inches, we find the percentage to be 19.81. In other 
words, about one-fifth of the females 9 inches or more in length bore eggs. 
The catch off No Man’s Land in May, 1894 (table 1), illustrates very well how 
the conditions are affected by the locality. Out of 1,318 lobsters taken 93.5 per cent 
were females, and 63.7 per cent carried eggs; moreover, 68 per cent of the total number 
of females bore eggs. 
