Sex Ratios in Pigeons. 
493 
season, and a lessened activity at the beginning of the season, leading 
up to the maximum. 
If a female which laid one of the earliest A-eggs (1-2 P. M.) had 
laid the second egg among the latest of those recorded (3-4 P. M.) 
the interval would have been 50 hours; on the other hand the shortest 
possible interval (A, 6-7 P. M.; B, 8-9 A. M.) by the same method 
of calculation would have been 38 hours. As a matter of fact we 
have seen (Fig. 3) that the shortest interval between the laying of A 
and B was 42 hours and the longest 47 hours. This suggests a dis¬ 
tinct positive correlation between the time of laying of A and B, and 
in Table V the data are displayed in the form of a correlation table. 
Table V .—Correlation between times of laying of first and second eggs. 
Time of laying second egg. 
o 
o 
o 
o 
o 
O 
O 
© 
co 
CO 
co 
co 
CO 
CO 
CO 
CO 
00 
05 
o 
r— < 
<n 
rH 
<N 
CO 
} 
o 
1 
o 
i 
o 
© 
i 
o 
1 
o 
4 
4 
m 
CO 
CO 
co 
CO 
CO 
CO 
CO 
CO 
*03 
00* 
o> 
o 
rH 
<N 
rH 
r—1 
rH 
rH 
U-t 
O 
12:30—1:30. 
i 
1 
ho 
.2 M 
>1 M 
1:30—2:30. 
1 
1 
c5 « 
2:30—3:30. 
1 
3 
3 
1 
8 
u-4 m 
O *h 
CD ^ 
3:30—4:30. 
1 
8 
20 
5 
34 
S 
4:30—5:30. 
1 
9 
15 
6 
3 
34 
H 
5:30—6:30.. 
5 
10 
8 
23 
Totals. 
1 
0 
i 
3 
25 
48 
20 
3 
101 
The distribution of the records in the table indicates some correlation, 
and the calculated coefficient gives r — + 0.38 +_ 0.057, which is a 
very sensible correlation. The equation to the regression straight line 
is y — — 0.48 + 0.378x, where x is the time P. M. of laying of the 
first egg, and y that of the second. By substituting in the formula 
the time that any given first egg is laid, the value of y gives the most 
