23 



Constants ralcnlatcd from Tabic 2. 



Pullets' mean fertility 7r)S<)± .011288 



Pullets' standard deviation 2C.()2± ,(H)79S2 



Yearlin-i; hens' mean fertility 7825^.012111 



Yearling hens' standard deviation 28r)()± .(K)8r)()4 



Coefficient of eorrelat ion 27;«i: .():«)238 



The mean fertility of the birds used in table 2 was slightly fjireatcr for the year- 

 Kng than for the pullet-year. The ditference, .02oG=b.()l()r)79, is not great enough 

 to be significant. The range of variability measured l)y 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 tiie 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 y(>arling. 



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

 year fertility supports the \\e\\' that fertility is a trait that is fairly constant for the 

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

 Pearl ('09) found a negative correlation of .lir2±.092 between infertility the first 

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

 tliat a bird with good fertility as a pullet will probably show good fertility as a 

 j yearling. 



Section 3. The Constancy of Hatching Power in Hens. 

 The group of 253 birds studied in table 2 are correlated for hatchability 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 hatchabihty 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? 



Table 3. — Correlation Between First and Second-Year natchabilit}j. 



