INHERITANCE OF INTENSITY 5 



Those mothers whose spring clutch size ranged from 4.2 to 5.7 were considered 

 of medium intensity and there were 71 individuals in this class. Daughters from 

 these mothers were extremely variable in spring clutch size, and there was no 

 correlation between mothers and daughters although regression was linear. 



Dams whose spring clutch size ranged from 5.8 upward were considered to be 

 highly intense. A total of 60 dams fell into this group. Regression of the daugh- 

 ters on mothers in this group was non-linear and examination showed that re- 

 gression was linear for mothers with a clutch size up to 10. There were 158 

 daughters from dams with a spring clutch size above 10, and here regression was 

 definitely non-linear. With 191 degrees of freedom, neither the correlation coeffi- 

 cient nor the correlation ratio is significant. 



Judged on the basis of the correlation between mothers and daughters, there 

 is no evidence in these data to indicate that selection of dams on the basis of 

 s pring clutch size is effective in increasing spring clutch size in daughters. 



Table 1. — Correlation Between Mothers and Daughters in 

 Clutch Size for Identical Periods. 



*Not statistically significant. 



Correlation in Summer Clutch Size between Mothers and Daughters 



High intensity may be difficult to maintain during the summer because of 

 unfavorable temperatures and the greater prevalence of diseases and disorders. 

 It is desirable, however, to know whether there is an intimate correlation between 

 mothers and daughters in summer intensity. Records were available on 230 dams 

 with 2006 daughters. 



The data show that summer clutch size was highly variable in both mothers 

 and daughters, the actual range being from 1 to 15 for dams and from 1 to 22 

 for daughters. The mean summer clutch size of both mothers and daughters 

 was essentially the same as the mean winter clutch size. Regression was non- 



