Jan. 20, 1919 Variations and Mode of Secretion of Milk Solids 



91 



Table X. — Correlation sutface for amount of milk and amount of butter fat as deduced 

 from individual year records of Holstein-Friesian cows 



Weight of butter (at (pounds). 



280-300. . 

 300-400. . 

 400-500. . 

 500-600. . 

 600-700. . 

 700-800. . 

 800-900. . 

 900-1,000. 



Total. 



Weight of milk (pounds). 



63 



85 



(59) 

 6 



74 59 



23 



2 



44 



105 

 122 



45 



14 



2 



335 



Table XI. — Correlation surface for amount of m,ilk and solids-not-fat as deduced from, 

 individual year records of Holstein-Friesian cows 



These tables show that the variables butter fat and solids-not-fat 

 are highly correlated with the amount of milk produced. The cor- 

 relation coefficient for butter fat and milk is r = 0.8644 ±0.0093 and the 

 correlation ratio 77 = 0.8638 ±0.0093. The correlation coefficient for 

 solids-not-fat and milk is r = 0.9497 ±0.0036 and the correlation ratio 

 is 77 = 0.9484 ±0.0037. As in the preceding case, these variates are 



