50 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



NUMBER OF EGGS LAID AND THE LAW OF PRODUCTION. 



The production of ova among animals is directly correlated with the condition of 

 the young at the time of hatchiug. Where eggs are very small and present in large 

 numbers, as in some of the crabs, we may look for a long larval period ; when the ova 

 attain a much greater size and are at the same time very abundant, as in the lobster, 

 we And the larval period abbreviated; in other cases, as in some shrimps, where eggs 

 are relatively very large and few, the young hatch with the external characteristics of 

 the adult. 



The production of a large number of eggs always means great destruction under 

 natural conditions. In such cases, however, the opportunity is afforded of increasing 

 the supply of adults, provided we are able to tide the larvae over their earlier stages 

 of development. The number of eggs produced by the lobster is thus a subject which 

 deserves careful attention in view of its economic bearings alone. 



The numbers here recorded are based upon the records kept at the United States 

 Fish Commission station. The eggs of each individual were carefully removed from 

 the "tail" of the female lobster and measured in a graduate (having sloping sides), 

 and the whole number of ova was estimated on the basis of the number contained in a 

 fluid ounce. .Mr. Edwards found the number of new eggs in one fluid ounce to be about 

 6,440 (in one ounce 6,461, in another 6,419), and the number of old or well-developed 

 eggs in an ounce to be 6,090. This is a relatively rough method of determination, and 

 the results are of course only approximately accurate. 



I estimated by weight the number of fresli eggs carried by a lobster 13 inches long 

 to be 17,623; total weight of eggs, 54.9 grams; number of living eggs to the gram, 321. 

 These eggs were in an early stage of development. 



The number of eggs borne by a large and a small lobster, carefully determined 

 both by the wet and dry methods by my assistant, Mr. F. C. Waite, is given in the 

 following table: 



Table 14. — The production of eggs determined by different methods. 



Observations. 



Lobster No. 51, 



table 20 ; from 



Gay Head. 



Lobster No. 69, 



table 20 ; from 



Woods Hole 



Harbor. 





Late segmen- 

 tation. 



15J 



815 

 1. 2255 

 68. 8092 

 220 

 6,248 



Post-nauplius; 

 about three 

 ■weeks old. 

 94 

 1,009 



0. 9893 

 10. 4029 

 211 

 5, 992 

 10, 507 

 10, 514 

 10, 919 















Number of eggs determined by the dry method (a) . 

 Number of eggs determined by the dry method (b) . 

 Number of eggs determined by the wet method (c) . 



56, 079 

 56, 148 

 58, 500 



Mr. Waite estimated the number of eggs in a fluid ounce (en the basis of 2,110 

 to 10 c.c, the number obtained by count) to be 5,992. These eggs had been in strong- 

 alcohol for upwards of three years. They were about three weeks old when preserved, 

 and in alcohol had an average diameter of 1.625 mm. (1.56, 1.69 mm.) 



In the wet method (c) employed, the number of eggs was estimated upon the 

 actual number, obtained by counting, in 10 c, c. In the dry method the number was 



