116 
Heredity in Production of Butter Fat 
(d) Cows 3 years old (2'5 — 3'5). 
2 = 2-21, 
= 11-75 - 8-8 = 2-95, 
//' = - 0-525, 
a = 2-89. 
(e) Cows 4 years old (3-5 — 4-0). 
2 = 2-10, 
7'/ = 2-84, 
// = _ 0-33, 
a = 3-06. 
{f) Corrected standard deviation for the entire group of cows under 4'5 years 
old. This standard deviation I obtain from the standard deviations of arrays up 
to 4-5. That is to say, we pool together the arrays with their corrected means and 
standard deviations. This gives for all cows under 4-5 years old 
<7, = 2-94. 
{g) Ratio of variability of selected group to that of total group. Let /i represent 
the ratio, then fju has the following values : 
For group over 4-5 years old, yLi = 0-57. 
For group under 2-25 years old, = 0-75. 
For group under 4-5 years old, /i, = 0-85. 
(/;) Values of corrected correlations. By means of (2) we now give the values 
of some corrected correlation coefficients. 
Dams and offspring : 
For mature cows, r = 0-63 from R = 0-284 of selected group. 
For cows under 2-25 years old, r = 0'25 from R = 0-145. 
For cows under 5 years old without regard to age in selecting pairs, r = O'lS 
from R = 0'132 for selected group. 
Granddams and offspring : 
For maternal granddams (mature), r = 0'38 from i2 = 0-138. 
For paternal granddams (mature), r = 0-25 from R = 0-086. 
Correlation between dams and dams of sires with which they are mated 
(mature), r = 0-39 from R = 0-U. 
