December 8, 1916] 



SCIENCE 



831 



ried) the theory seemed to fit the facts, 

 day it does not. 



To- 



The question to be answered is this : How is 

 it that off the Massachusetts coast in 1910, 

 only about 2 per cent, of the females carried 

 eggs? Even if the figures are not absolutely 

 correct, the general falling off in percentage 

 since 1888 is most marked. In Canada, we 

 have collected no statistics until this year 

 (1916), and Mr. Halkett's returns show that 

 an average of about 97 per cent, carry no eggs. 

 Are these females all sterile? Impossible be- 

 lief! 



For the Canadian coast, therefore, it is clear, 

 that the percentage of females which carry 

 eggs in traps varies from less than 1 per cent, 

 in the Bay of Fundy area (which may be 

 said to include St. Mary's and St. Andrew's) 

 to about 4.2 per cent, in Northumberland 

 Straits; whereas, by mating experiments in 

 these same areas the percentages are increased 

 by an average of 3,000 per cent, in the former 

 and 1,600 per cent, in the latter area. 



i The estimate of females, as half of the totals 

 is mine. — A. P. K. 



2 Number of lobsters above 9 inches. 



Early in our experiments this summer the 

 possibility occurred to me that females in the 

 open sea might in autumn carry more eggs 

 than they do in spring and early summer. In 

 other words, many females might for one rea- 

 son or another lose their eggs during the 

 winter, and thus reduce the percentage to that 

 elucidated by Mr. Halkett. This possibility 

 was tested to some extent during August and 

 September (1916). Through the courtesy of 

 the Minister of Fisheries, the Hon. J. D. 

 Hazen, I was permitted to fish for lobsters from 

 August 19 to August 31, and found the per- 

 centage to 2J per cent, for the Pictou area. 

 Fishing was again resumed during the last four 

 days of September, when the percentage was 

 found to have increased to 5.6 per cent. 

 Moreover, during September we had 25 males 

 and 25 females confined in the mating pen, 

 and although the enclosure gave way at one 

 corner and allowed some of the lobsters to 

 escape, nevertheless 13j per cent, of the fe- 

 males were found to have extruded eggs. Here 

 the increase by mating is quite clear. 



While I dislike theorizing at this stage in 

 the experiments, I may be permitted to suggest 

 that probably the majority of female lobsters 

 extrude their eggs every year; but that as the 

 total males and females are now greatly re- 

 duced through overfishing, and relatively 

 widely separated from each other in the open 

 sea, there is less copulation than formerly, with 

 consequent lack of fertilization of eggs. Being 

 unfertilized the eggs soon " go bad," and drop 

 off. On the other hand, mating brings the 

 sexes together with a resulting increase in the 

 numbers of females carrying fertilized eggs. 



We may safely conclude, therefore, that the 

 efficacy of mating as a means of increasing 

 the number of berried females is fairly well 

 established, on the supposition, of course, that 

 the catch of berried females fairly represents 

 the number of berried females in the bottom 

 of the sea. At any rate, the results amply 

 justify further experiments on a large scale, 

 and if further results prove as successful as 

 those of the past three years, they far surpass 

 the results of either lobster hatching or lobster 



