Jan. 20, I9I9 Variations and Mode of Secretion of Milk Solids 



85 



determined, and the means of the separate distributions lead us to a 

 correlation ratio, which, while small, is highly significant in showing the 

 dependence of butter -fat concentration on amount of milk. 



These studies limit themselves to the relation of butter fat to the milk. 

 In dealing with this question the association of the percentage solids- 

 not-fat with the quantity of milk produced will also be studied. Tables 

 IV and V show the correlation surfaces for weight of milk and percentage 

 of butter fat and the age of the cow and the percentage of butter fat. 



Table IV. — Correlation surface for amount of milk and percentage of butter fat as 

 deduced from, individual year records of Holstein-Friesian cows 



Table V. — Correlation surface for age at the beginning of test and percentage of butter 

 fat contained in the milk for the individual records of Holstein-Friesian cows 



