46 



number of birds. The actual date may be calculated easily in each case. It is 

 interesting to note that the pullets averaged 3.96 pounds at 150 days old. 



The coefficient of correlation between hatching date and 150-day weight is 

 — .3'-293±.0194. This is a significant correlation and substantiates common 

 observation that early hatching tends to give larger pullets at a given age than 

 does late hatching. In about one case out of three there was direct associ- 

 ation between early hatching and heavy weight. In the other two cases out of 

 three there was no relation between 150-day weight and hatching date. Other 

 influences were operating in two cases out of three to overcome any effect of 

 liatching date on weight at 150 days. 



Hatching Date versus Weight at First Egg. 

 Number of birds 820 



Mean hatching date .... 

 Hatching date standard deviation 

 Mean weight at first egg 

 Weight at first egg standard deviation 

 Coefficient of correlation . 



6.66 

 ±2.92 



5.65 

 ± .75 

 -.3807 ±.0201 



The mean weight at first egg is 5.65 pounds. The coefficient of correlation 

 Ijetween hatching date and weight at first egg is —.3807 ±.0201. The corre- 

 lation shows that early hatched pullets tend to be heavier when they lay their 

 first egg than do their later hatched sisters. This fact is in accord with the 

 observations on weight at 150 days. In four cases out of ten the weight at 

 first egg is directly associated with hatching date. Possibly the degree of 

 correlation between time of hatching and weight at first egg is greater than 

 that between time of hatching and 150-day weight because late hatching tends 

 to reduce the mean age at first egg as will be shown below. 



Hatching Date versus Age at First Egg. 

 Number of birds 

 Mean hatching date 

 Hatching date standard deviation 

 Mean age at first egg 

 Age at first egg standard deviation 

 Coefficient of correlation 



840 



6.64 

 ±2.92 

 210.99 days 

 ±28.91 



-.1487±.0228 



The mean age at first egg is 210.99 days and its standard deviation is 28.91. 

 Thus the age range is wide as will be observed from the relative magnitude of 

 standard deviation and mean. 



The coefficient of correlation is negative and amounts to .1487 ±.0228. 

 Thus in one case out of seven late hat,ching is associated with early sexual 

 maturity. Such a constant suggests that late hatching tends to reduce the 

 length of growth period prior to laying and this is in part responsible for the 

 lighter weight at first egg in late pullets compared with early ones as was 

 pointed out in the previous section. 



Hatching Date versus Winter Production. 

 Number of birds 802 



Mean hatching date 



Hatching date standard deviation 



Mean winter production 



Winter production standard deviation 



Coefficient of correlation 



6.59 



±2.97 



44.48 



1 23.06 



-.2920 ±.02 18 



The mean egg production of the 802 birds studied up to March first is 44.48. 

 The magnitude of the standard deviation shows a wide range in winter 

 fecundity within the flock. This wide range in fecundity is to be expected 

 because of the range in hatching date and because of the range in age at first egg 

 as well as because of genetic dift'erences in the individuals in winter pause, 

 intensity, and broodiness. 



