Is there a Cumulative Effect of Selection? 267 
comparative figures for the egg production of mothers and daughters 
are given in Table II. In discussing the results of this experiment 
the egg production of the winter months (November ı to March 1) 
and of the spring months (March ı to June 1, the natural mating 
and breeding season of the birds) will be considered separately. 
From the data set forth in this table and additional ones given 
in the detailed report the conclusions given below may be drawn. 
It will be understood that considerations of space forbid giving here 
the entire evidence on which these conclusions rest. For the detailed 
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99-00 00-01 01-02 02-03 03-04 04-05 05-0b 06-07 
Fig. 3. Diagram showing change in variability of flocks in egg production during 
the course of the selection experiment. The zigzag line gives the observed coefficients 
of variation. 
presentation and critical analysis of this evidence the complete papers 
already referred to (p. 257 supra) must be consulted. 
1. The daughters of ‘‘200-egg”’ or “registered” hens are markedly 
inferior to their mothers in egg production for both of the periods 
studied. This difference is particularly great in the winter (Nov. 1 — 
March 1) period. It is evident that the daughters do not belong in 
anything like the same class as the mothers as winter egg producers. 
The mothers’ average production for the corresponding period of their 
pullet year was nearly 4 times as great as the daughters’. (Exactly 
45.5 + 12.7=3.7.) This great reduction of the daughters’ average 
winter production below the mothers’ is most striking and unexpected. 
It is to be expected on general grounds that there would be some 
regression, but so much as this would hardly have been anticipated. 
2. Quite apart from the question of the average production of 
mothers and daughters the data gives no indication that there is any 
sensible correlation between individual mothers and individual daughters 
