23 



Constants calculated from Table 2. 



Pullets' mean fertility . • • • 7589db. 011288 



Pullets' standard deviation 2662±. 007982 



Yearling hens' mean fertility 7825±. 012111 



Yearling hens' standard deviation 2856±. 008564 



Coefficient of correlation 2733 ±.039238 



The mean fertihty of the birds used in table 2 was slightly greater for the year- 

 ling than for the pullet-year. The difference, .0236±. 016579, is not great enough 

 to be significant. The range of variability measured by the standard deviation is 

 slightly wider as yearlings than as pullets, but the closeness of agreement in the 

 two years signifies a degree of fixedness. From the breeding standpoint, the chief 

 deduction that may be made from a study of table 2 is that the percentage of fer- 

 tility for a pullet is a good guide as to her probable fertility as a j^earling. 



A positive coefficient of correlation, .2733 ±.039238, between the first and second 

 year fertility supports the view that fertility is a trait that is fairh^ constant for the 

 individual hen. Lamson and Card ('20) have pointed out this fact in Leghorns. 

 Pearl ('09) found a negative correlation of .1112±.092 between infertiUty the first 

 year and the second year in Barred Plymouth Rocks. Our data, however, indicate 

 that a bird with good fertihty as a pullet will probably show good fertility as a 

 yearling. 



Section 3. The Constancy of Hatching Power in Hens. 

 The group of 253 birds studied in table 2 are correlated for hatchabiUty in table 

 3 to discover if there is a relationship between the percentage of fertile eggs hatched 

 as pullets and as yearlings. In other words, does hatchability approach any degree 

 of constancy in the same individual in two successive years? Does a good hatching 

 record as a pullet mean a good hatching record as a yearling? 



