VARIATIONS OF MILK CONSTITUENTS 163 



Turning- now to the results obtained at cheese-fac- 

 tories, we have the following data : 



VARIATION OF CASEIN IN CHEESE-FACTORY MILK WITH 

 ADVANCE OF LACTATION 



In the foregoing figures, we see that the percentage 

 of casein in milk increases in May and still more in 

 June, after which a decrease takes place in July, fol- 

 lowed by still further decrease in August. There is a 

 rapid recovery and advance during September and 

 October. The cause of these variations will be con- 

 sidered later. 



Influence of change from barn to pasture upon 

 the percentage of casein. Attention has already 

 been called to this subject in relation to fat. We now 

 give corresponding figures for casein. During the 

 first half of May, the milk contained 2.25 per cent of 

 casein and during the second half of May, 2.45 per 

 cent. The same explanation applies as in the case 

 of increase of fat. 



Influence of drouth upon the percentage of casein 

 in milk. During a time of severe drouth in New 

 York, beginning in July and lasting through Au- 

 gust, with infrequent and insufficient showers, a 

 marked decrease was noticed in the casein of the 

 milk, even when the fat was increasing. The ana- 



