52 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



In casting tbe eye down the column of averages ' in table 15, we are immediately 

 struck by the fact that a 10-inch lobster bears about twice as many eggs as one 8 

 inches long, and that a 12-inch lobster has double the number borne by one which 

 measures 10 inches. 



It is therefore suggested that in the early years of sexual vigor there is a general 

 law of fecundity or production which may be formulated in this way: The numbers of 

 eggs produced by female lobsters at each reproductive period vary in a geometrical series, 

 while the lengths of the lobsters producing these eggs vary in an arithmetical series. It is 

 safe to assume that the avearge number of eggs laid by a lobster 8 inches long is not 

 above 5,000. If such a law prevails we would have the following: 



Terms. (1) 



(2) 



(3) 



(I) 



(5) 



(6) 



Series of lengths in inches. . 8 

 Series of eggs 5,000 



10 

 10, 000 



12 

 30, 000 



14 



40, 000 



16 

 80, 000 



18 

 160, 000 



An examination of table 15 shows how closely the first four terms of this series 

 are represented in nature, and that when the 14 to 10 inch limit is reached, there is a 

 decline in sexual vigor. Yet the largest number of eggs recorded for lobsters of 



Length of 



animal in inches 

 is 



10 



14 



12 



to 



O I I 1 I I /l I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I II I I I I I Ill 



O ,'\ lOOOO 20000 30000 4QOOO 50OOO OOOOO lOOOO 80000 Eggs 



Cut 1. — Curve of fecundity of the lobster. 



I division on ordinate corresponds to 2 inches m length of lobster. 1 smaller division on abscissa represents 1,000 eggs. 



aa, curve deduced from law of production as theoretically stated. 



bb, curve of fecundity deduced from observations recorded in table 15, for lobsters 8, 10, 12, 14, and 16 inches long. 



this size shows that there is a tendency to maintain this high standard of production 

 even at an advanced stage of sexual life. 



1 It is a conspicuous fact that in the fifth column of table 15 the largest numbers refer to 

 individuals whose length is expressed in even inches or half inches. This is of course the result 

 of inaccuracy in taking measurements: the quarters have been somewhat neglected. 



