144 MAIXE AGRICULTURAL EXPElRIMENT STATION. I909. 



TABLE XXIII. 



Comparison of fathers' Average Pen Records of Infertility and 

 Hatching of Eggs, with the same Characters in their 

 Daughters. 



laid bv all the birds in the pen headed by each cockerels. Pro- 

 vided sufficiently large numbers of females are used with each 

 male in a breeding pen so that it may be supposed that they 

 give a fair random sample of breeding females in general, the 

 average fertility and hatching quality of eggs from the pen 

 through the whole season may be taken as in some degree a 

 measure of that particular male bird's breeding ability. 

 Assuming that the females represent average samples, 

 dififercnccs in the average fertility and hatching quality 

 of the eggs from different pens may be attributed to innate 

 differences in the breeding ability of the cockerels, always 

 provided other conditions are kept the same. Now this ques- 

 tion may be raised : What is the degree of correlation existing 

 between a male bird's average pen fertility of eggs (such as is 



