GENETICS: HARRIS, BLAKESLEE AND WARNER 
239 
great indeed, but the number of birds included in the heavy laying 
class is sufficiently large for practical selection operations. 
The correlations for October pigmentation and egg production for 
the individual months, represented in Figure 2, are without excep- 
tion negative in sign. The agreement between the results for the two 
years is very close indeed.^ 
1 1 I I I I I I \ I L ( 
> u z m o:' Q:' > z J ^ t ^-* 
ZQ^iZ2<2=S=!<(nO 
FIG. 2. 
Thus there is not merely a strong negative correlation between the 
October ear lobe pigmentation and the egg production of the year as a 
whole, but there is a negative correlation between October ear lobe pig- 
mentation and the egg records of each of the preceding twelve months. 
The simplest physiological hypothesis to explain the demonstrated 
negative correlation between egg production and intensity of pigmen- 
