]86 TECHNICAL BULLETIN 11 



large winter clutch size tliat may be employed advantageously in breeding 

 for egg production. 



5. Corrchition Heticeeii M'eufhf tif Firnt J'^;/;! <ni<l Menu Clutch Size. 



Because of the importance both of body weight and of clutch size in 

 breeding for fecundity, it is very desirable that their relation to each 

 other be ascertained. The correlation between weight at first egg and 

 mean clutch size was calculated with the following constants; 



Number of birds 3797 



Mean weight 5.53 



Weight standard deviation ±.72 



Mean size of winter clutch 2.65 



Winter clutch standard deviation ±1.29 



Coefficient of correlation — .1714 i!=.O106 



The coefficient of correlation is found to be iiegiitive and its absolute 

 magnitude is not very great. Statistically, however, the correlation is 

 significant and suggests something of a tendency for smaller birds to ex- 

 hibit larger clutches. For purposes of prediction or selection the relation 

 is not sufficiently pronounced to be of value. 



(j. Correhifi'Hi lieticeeii ]\'uitcr l'n><h(rt!i»i hikI Menu Clufcli Xize. 



Heavy winter egg production is important both genetically and economic- 

 ally. Genetically, winter egg record depends on seven pairs of Mendelian 

 factors as has been shown by Hays (1924), and winter production is also 

 known to be intimately correlated with annual production (Hays, Sanborn 

 and James, 1924). Economically, the number of winter eggs is of no small 

 value in affecting the net income per bird. In breeding for high fecundity 

 it is necessary to recognize both environmental influences and hereditary 

 factors that are concerned in winter egg yield. By tabulation of the entire 

 population for clutch size and winter record the constants below were 

 secured: 



Number of birds ;^867 



Mean winter production 62.92 



Winter production standard de\ iation ±25.95 



Mean size of winter clutch 2.64 



Winter clutch standard deviation ±1.29 



Coefficient of correlation +.4727 ±.0084 



The above coefficient of correlation suggests a rather intimate positive 

 relation between clutch size and winter record. This constant may be 

 considered a true measure of correlation and indicates an important rela- 

 tion between clutch size and total egg yield for the winter. In view of 

 this fact large clutch size should be considered as a vital factor in breed- 

 ing for maximum winter egg records. 



7. Correlation Beticeen Annual Record and Mean Clutch Size. 



Clutch size appears to behave in Mendelian fashion in inheritance. It 



