47 

 A negative coefficient of correlation amounting to .'•29'-20±.0'-218 exists be- 

 tween hatching date and winter production. All other conditions being the 

 same, there could not but be a negative correlation because the early hatched 

 pullets have longer to lay. The fact that in less than one case out of three is 

 early hatching directly associated with greater winter egg yield can be due 

 only to the condition that a good percentage of early hatched pullets complete 

 their winter cycle of laying and lose considerable time in winter pause while 

 fewer later hatched pullets actually pause. 



By reducing the range in age at first egg, a more accurate measure of the 

 degree of association between early hatching and high winter egg production is 

 obtained. The coefficient of correlation has been calculated between hatch- 

 ing date and winter egg record using only those birds beginning to lay at 20(5 

 days or less. The constants obtained on this group are as follows : 



Number of birds ...... 



Mean hatching date ..... 



Hatching date standard deviation 



Mean winter production ..... 



Winter production standard deviation . 

 Coefficient of correlation .... 



In the above group of birds the 70 day range in hatching date is greater than 

 the 50 day range in age at first egg. In other words, all birds maturing at 206 

 days or less are the same genetically for sexual maturity as was pointed out 

 earlier (Hays 1924). With such a group of birds high winter fecundity is asso- 

 ciated with early hatching in fifty per cent of the cases. 



Evaluating hatching date entirely from the standpoint of desirable char- 

 acteristics that are associated with winter fecundity, these deductions seem 

 warranted from the preceding four correlation studies: 1. That early hatched 

 pullets are heavier in weight both at 150 days old and when they lay their 

 first egg than are late hatched ones; 2. that late hatching tends to reduce the 

 age at first egg; and 3. that early hatching gives greater winter egg yields, 

 but there must be a certain optimum hatching time which gives the most un- 

 interrupted winter egg production. 



Winter Production. 



The total number of birds is divided into classes of winter producers with a 

 range of ten eggs beginning with those laying from to 9 eggs and ending with 

 those laying from 130 to 139 eggs during the winter season. Winter produc- 

 tion is studied in its general relation to hatching date, age at first egg, weight 

 at 150 days, weight at first egg, and daily gain in weight between 150 days old 

 and age at first egg. 



Table II 



