196 THE dairyman's manual. 



lostrum the epithelial cells have not undergone this de- 

 structive change, the walls are still intact and contain 

 their oil granules, and thus constitute the corpuscles of 

 this fluid. In the colostrum albumen takes the place of 

 caseine in the perfect milk, but a reverse change is 

 slowly made and completed about the fourth day. At 

 the end of lactation, when the animal is again pregnant, 

 the milk again loses its caseine and gains albumen, and 

 is consequently easily coagulable by heat and causes 

 many serious difliculties in the dairy Avhich are not easily 

 understood by the dairyman who is unfamiliar with 

 these facts. The sugar also disappears in part or w^holly, 

 and the leucocytes increase as in the colostrum. 



About the fourth or fifth day after parturition the 

 milk becomes normal in character and is fitted for gen- 

 eral use. It however always contains more or less al- 

 bumen, and this is a common source of trouble in the 



dairy, especially in win- 

 ter, when heat is used to 

 effect the necessary acid- 

 ity or ripening of the 

 cream. The albumen is 

 thus solidified and causes 

 the troublesome white 

 Fig. 23. specks in the butter. 



When the milk glands first assume their tumefied or 

 swollen condition, just previous to parturition, the lob- 

 ules of the glands become filled with a largely increased 

 number of cells (figure 23, h), and these greatly increase 

 the size of the udder. Previous to this condition the 

 lobules are shrunken (figure 23, a) and the formation 

 and constant destruction of cells, as they are formed, 

 are occurring continuously, and it is only when the 

 udder is charged and filled vrith milk that it is distended. 

 But when the active development of cells is in progress, 

 the lobules of the glands are enlarged and do not break 



