INHERITANCE OF INTENSITY 7 



mothers in mean fall clutch size, but there was no correlation between mothers 

 and daughters. Regression was found to be linear by Blakeman's test. 



The small group of dams with a fall clutch size of 3.3 or greater was considered 

 highly intense. In the population studied there were 55 dams in this class. The 

 mean clutch size of their daughters was slightly greater than was observed for 

 the daughters of medium dams. Although regression was linear, with 144 degrees 

 of freedom, the coefficient of correlation was insignificant. 



In general, selection of breeding females on the basis of fall clutch size does not 

 appear to be a satisfactory method, judged by the character of daughters pro- 

 duced. It seems probable, therefore, that careful progeny' testing is necessary 

 to solve the intensity problem. 



SECTION 2. VALUE OF FOUR TYPES OF INTENSITY RECORDS 

 IN DAMS FOR PREDICTING INTENSITY OF DAUGHTERS 



Section 1 of this report was concerned with the correlation between mothers 

 and daughters in clutch size for each of the four seasons of the j-ear. Section 2 

 gives consideration to the value of clutch size of mothers during each of the four 

 periods in relation to the clutch size of daughters during other seasons of the year. 

 For example, is there a significant association between dams' winter clutch size 

 and daughters' spring, summer, and fall clutch size? All such combinations are 

 shown in Table 2 and discussed in this section. 



Table 2. 



-Correlation Between Mothers and Daughters in 

 Clutch Size for Different Periods. 



Periods 



Number Number Coefficient Correlation 



of of of Ratio 



Dams Daughters Correlation 



Dams' winter clutch size and 

 Daughters' spring clutch 

 Daughters' sunimer clutch 

 Daughters' fall clutch 



Dams' spring clutch size and 

 Daughters' winter clutch 

 Daugnters' summer clutch 

 Daughters' fall clutch 



Dams' summer clutch size and 

 Daughters' winter clutch 

 Daughters' spring clutch 

 Daughters' fall clutch 



Dams' fall clutch size and 

 Daughters' winter clutch 

 Daughters' spring clutch 

 Daughters' summer clutch 



*Not statistically significant. 



Winter Clutch Size of Dams 



The same population was examined as in Section 1, but the number of indi- 

 viduals varies somewhat, largely because of mortality during the year. From 

 237 dams with a winter record, 2315 daughters with spring records were obtained. 

 The data show that mean spring clutch size in daughters was essentially the same 

 as the mean winter clutch size in their mothers. The fact should be noted that 



