yo MAINU AGRICULTURAL E;XPE;RlMIi:NT STATION. I909. 



to make a study of the correlation between the mother's indi- 

 vidual performance and th;: daughter's average performance for 

 each of the ^gg laying periods here under discussion, in order 

 to compare the results so obtained with the results which one 

 gets by the more usual method of allowing the mothers' 

 records to be weighted with their fecundity. In determining the 

 degree of correlation in this way it is neither necessary nor 

 desirable in the present case where we are dealing with such 

 small numbers (31 mothers only) to make a correlation table 

 for the evaluation of the coefficient. Instead the correlation 

 coefficient may most accurately be determined directly from the 

 data given in Table I without grouping. 



Besides the evidence as to the inheritance of ^gg producing 

 ability afforded by the coefficient of correlation between mother 

 and daughter in respect to this character, light may also be 

 obtained on the problem from the relative values of constants 

 measuring variability in ^gg production. It is a fundamental 

 principle of breeding by selection that the offspring of selected 

 parents will be less variable than the offspring of unselected 

 parents, or, in other words, than the general population. It is 

 to be expected that following selection there will be a reduction 

 in variability. Selection is made to a type and if a line of 

 breeding is successful it is justifiable to assume that the off- 

 spring after selection will conform more closely to the type than 

 did the individuals before selection. It is, on this account, 

 important in all discussions regarding the inheritance of a char- 

 acter to determine the variability of that character following 

 selection. In the present case the variation can be measured 

 by well known and accurate methods in connection with the 

 mathematical processes involved in determining the correlation 

 coefficients. The variation constants will be tabled with the 

 correlation coefficients. 



The constants of variation and correlation measuring the 

 degree of inheritance in ^gg production exhibited in this experi- 

 ment are shown in Table VI. These constants have been deter- 

 mined from the data given in Tables I, III, IV, and V. 



