Relation of Fat to Casein. 



165 



Van Slyke,* in a series of investigations extend- 

 ing over several years, and including the milk of not 

 less than fifteen hundred different cows, found that as 

 the percentage of fat increased the percentage of 

 casein increased in a nearly constant ratio ; or, to 

 quote his own words : "While we have noticed con- 

 siderable variation when we considered individual 

 herds, we have found that, as a rule, there were two- 

 thirds of one pound of casein for each pound of 

 fat in the milk, whether the milk contained 3 or 4 

 per cent of fat ; though this normal relation was con- 

 siderably affected in the season of 1893 by the effects 

 of drought upon the pastures. * * >i^ >i< When 

 the amount of fat in the milk increased beyond 4% 

 per cent, there was a gradual but slight diminution 

 of casein for each pound of fat." 



The accompanying tables give the data upon which 

 Dr. Van Slyke's opinions were based : 



Table showing relation of fat to casein in normal milJc. 



*New York Agricultural Experiment Station, Bulletin, No. 68, New Series. 



