30 



MILK HYGIENE 



specific gravity of 1.040 to 1.080. Its microscopic ap- 

 pearance has been described before and, in part, its 

 chemical composition. Gradually, the appearance and 

 the composition of the secretion changes untU, in the 

 course of about a week, it becomes pure milk. This 

 gradual development is illustrated by the following 

 analysis given by Eugling: 



Noimal 

 milk. 



Water 



Casein 



Albumin i 

 Globulin j 

 EztractiTeB 



Sugar 



Ash 



87.75 

 3.00 



0.50 



3.40 

 4.60 

 0.76 



These figures show that the chief difference in the 

 composition of milk and colostrum consists in the 

 greater albumin and globulin content of the latter, which 

 arises partly from the presence of numerous colos- 

 trum bodies, in consequence of the presence of which 

 colostrum coagulates when heated. Another important 

 difference is the low sugar content of colostrum ; accord- 

 ing to Tereg the sugar of colostrum is not lactose, but is 

 grape sugar, or perhaps a mixture of this and galactose. 

 Of the substances that are extracted with the fat, about 

 13.8 per cent, consists of cholesteria and 8.0 per cent, 

 of lecithin. 



Among other peculiarities shown by colostrum of the 

 cow may be mentioned its acid reaction and the fact that 

 after the addition of rennet it does not coagulate at aU, 

 or only very slowly. 



b. MUk. Shortly after calving, while the secretion 



