270 



EARL W. BENJAMIN 



for weight. Of course these two factors are likely to be very closely 

 associated. The weight correlations are much more distinct than those 

 for vigor during most of the year. The vigor correlations decreased 

 after the early weeks, until some very severe winter weather just previous 

 to the thirty-sixth week's recording. After the thirty-sixth week, how- 

 ever, abnormally early spring weather prevailed, the vigor of all birds- 

 improved wonderfully, and the correlation entirely disappeared. 



From the observations just noted, it seems that the test of the vigor 

 of a chick, that is to say, when the size of the parent egg is of real 

 benefit, comes during the season of greatest hardship to the birds. The 

 weights are not affected by the seasonal conditions quite so definitely as is 

 the vigor. 



Relation between male and female weights for chicks of the same age 

 During the first forty weeks of the 1911 hatch, and the first seventy-six 

 weeks of the 1912 hatch, the male and female weights were averaged 



TABLE 61. 



CONSTANTS REPRESENTING X IN THE FORMULA: FEMALE WEIGHT : MALE 

 WEIGHT : : X : 1 



* No male weights were obtained at this age in 1912. 



