52 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
In casting the eye down the column of averages 1 in table 15, we are immediately 
struck by the fact that a 10-iuch lobster bears about twice as many eggs as one 8 
inches long, and that a Ill-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) 
(4) 
(5) 
(6) 
Series of lengths in inches. . 
8 
10 
12 
14 
16 
18 
Series of eggs 
5,000 
10, 000 
20, 000 
40, 000 
80, 000 
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 16 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 
Cut 1. — Curve of fecundity of the lobster. 
I division on ordinate corresponds to 2 inches in 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. 
