ANNUAL PERSISTENCY AND EGG PRODUCTION 



197 



A slight but significant correlation is found to exist between winter rate of 

 laying and persistency. This correlation indicates that, in general, there is 

 some tendency for the more intense winter layers to persist in laying later in 

 the fall than do less intense layers. 



8. Correlaiion Between Winter Rate Greater than the Mean and Hiyh 

 Persist enct/. 



By classifying all birds with higher winter rates than the mean of the 

 whole population as high for rate, and by classing as highly persistent all in- 

 dividuals laying for 315 days or more, the following table gives the correla- 

 tion l)ctween high winter rate and the presence of ])ossible genetically high 

 persistency: 



Coefficient of correlation 



-f. 2236 ±.0138 



The above tabidation jjresents a moderate degree of positive correlation 

 between two inherited characteristics concerned in high fecundity. The very 

 significant fact is lirought to light tliat iugh winter rate and high persistency 

 are ]iartially complementary, and there is no evidence of antagonism between 

 the two. 



9. Correlation Be'iceen Len(jfh of M'inter Pause and .Ijinual Persiste/ici/. 



The presence or absence of winter pause has been shown by Hays (1924) 

 to dej^end upon genetic factors. The duration of the pause, however, may 

 depend upon environment as well as inheritance. Most environmental forces 

 affecting the duration of pause are probably beyond control of the breeder 

 and may not properly be considered in this report. This section is devoted 

 to a study of the correlation between length of pause and persistency as has 

 already been done by Hays and Sanborn (1926b). In the population being 

 studied there were 1348 birds with winter pause records which were divided 

 into ten-day class intervals and the following constants arrived at: 



Number of birds 

 Mean length of winter pause . 

 Pause standard deviation 

 Mean annual persistency . 

 Persistency standard deviation 

 Coefficient of correlation 

 Regression persistency on pause 

 Regression pause on persistency 



.0182 



