490 
Bulletin Xo. 162. — 1915. 
5. The mean time between the laying of eggs A and B is accord¬ 
ingly 44.21 hours, or 44 hours, 12 minutes. 
6. From the shape of the curves it might be inferred that there 
is somewhat greater variability in the time of laying of A than of B, 
although the range of the latter is slightly greater. A comparison 
of the standard deviations in the two cases, however, shows no 
significant difference. These are: for A, 1.008 jT 0.048 hours; for 
B, 1.002 + 0.048 hours. 
As stated above, the mean time intervening between the laying 
of eggs A and B is 44 hours and 12 minutes; the extremes are 42 
hours on the one hand and 47 hours on the other. The distribution 
of frequencies with respect to interval between layings is shown in 
Figure 3. The variability of this interval as measured by the 
Hours 41 42 43 44 45 46 47 48 
Frequencies 0 7 20 32 30 11 1 0 
Fig. 3- Curve showing interval in hours between laying of first and second eggs in 101 sets. 
