70 Report of the Chemist of the 



Our previous work has established fairly beyond question that 

 the fat and casein in milk tend to preserve a quite uniform rela- 

 tion from month to month as the period of lactation advances, 

 provided abnormal conditions are absent, such as insufficient 

 nutrition. We shall now study the relation of fat and casein in 

 the milk of different herds, taking each month by itself, and also 

 the season as a whole, thus eliminating any influence that might 

 come from advance of lactation. 



We present tabulated summaries of our detailed results. The 

 tables contain the following data: 



(1) The percentage of fat in milk arranged in groups, each 

 differing from the preceding and following by one-tenth of one 

 per cent. 



(2) The average percentage of casein corresponding to each 

 group. 



(3) The amount of casein for each pound of milk-fat in each 

 group. 



(4) The amount of cheese made from 100 pounds of milk in each 

 group. 



(5) The amount of cheese made for each pound of milk-fat in 

 each group. 



The number of herds embraced in each group is also stated. 

 A separate table is presented for each month of the season from 

 May to October inclusive, and also a table giving the herd aver- 

 ages for the entire season. 



In studying these results, it is well to keep in mind that the 

 yield of cheese, relative to milk-fat, varies directly with the 

 amount of casein relative to milk-fat. When the relative pro- 

 portions of fat and casein in milk remain uniform, the amount of 

 cheese produced for each pound of fat in milk remains the same. 

 When the casein in milk increases relative to the fat, then the 

 amount of cheese produced for each pound of fat increases. 

 When the casein in milk decreases relative to the fat, then the 

 amount of cheese produced for each pound of fat decreases. 



