NATURAL HISTORY OP AMERICAN LOBSTER. 297 



By means of the animals killed it was shown that from June 19, 1900, to May i, 1901, 

 during a period of 10 months and 12 days, the ovaries had undergone a slow and gradual 

 growth, a very important fact, which, if the conditions of growth were normal, is strong 

 evidence that in the American lobster annual spawning is not a usual occurrence. 



It was further demonstrated that the ratio of growth of the ovarian eggs for stated 

 periods implied a reproductive cycle of 2 years . (Compare fig. 30.) 



In conclusion we found that the theory of biennial spa wnint )- is suppnrfpH- (t) Ry 

 the statistics of the fishery; (2) by the anatomy of the ovarv of the adult female taken 

 at dilterent seas o ns; (3) by the ratio of growth of a given generation of ovarian ov a 

 for stated perioas; (4; py observation on animals kept alive for long periods; and (5) 

 by the evidence of the rapid growth of nv arian ^nr n^g nf cpawnprc fm- any given year 

 during the height of the breeding season . " 



Any rule to which the majority conforms may be expected to have exceptions. 

 A lobster may exceptionally lay eggs in two consecutive seasons, and it is possible that 

 in some cases the normal biennial period may be even prolonged. 



When the preceding paragraphs were written I had not seen a paper of Appelof 

 (6) in which he confirms the theory of biennial spawning in the European lobster by 

 an experiment conducted on a larger scale at the fisheries station at Stavangar, Norway. 

 His statement is as follows : 



Since the matter (the question of spawning) had not been decided by experiment, I selected 100 

 lobsters, which were kept in a natural basin in the neighborhood for this purpose. It can now be main- 

 tained with complete assurance that in fact 2 years elapse between each egg laying. " 



As already seen, a number of spawners, probably a very small proportion, lay out 

 of season, in fall and winter. How can we account for these exceptional cases? An 

 experiment tried by Mr. Cunningham {63) in the summer of 1897, on the European 

 lobster, suggests an answer to the question. At Falmouth, England, five female lobsters, 

 bearing external eggs which were nearly ripe, were placed in a floating box during the 

 summer. After their ova were hatched these females were kept confined with two 

 males until after October 14, when one was found to have newly spawned. This proves 

 that it is possible for the European lobster to produce eggs in two successive years, 

 but it does not prove that this is the common habit of the species in European waters. 

 It also strongly suggests that these October eggs may correspond to the fall and winter 

 eggs occasionally produced in the American form. By accelerated growth of the ovary 

 the ova might be laid in fall or winter when not normally due until the summer fol- 

 lowing. Under such circumstances the ovarian eggs would come to maturity in 15 

 instead of 23 months. It would be interesting to know when these autumnal eggs 

 hatch. The suggestion which we formerly made that they do not give rise to regular 

 summer broods should be withdrawn, for it seems to us now that more confirmatory 

 evidence is required before we can accept the statement that the young of the American 

 lobster are ever hatched in the sea outside the period embracing the nionths of May, 

 June, and July. 



oln referring to later experiments conducted at the lobster park, at Kvitingso, Appellof remarks: " The conclusion that 

 the female lobster on the west coast of Norway normally lays its eggs only once in two years, I later found year after year to be 

 completely confirmed." (See 305, p. 23). 



