MILK 35 



quently the epithelial cells are folded on themselves, when 

 they appear as rounded, oval, or irregular shapes, and 

 sometimes they are arranged in groups like the petals of 

 a flower. Degenerated and disintegrated cells, free nu- 

 clei, bacteria, and vegetable cells and fibres may also 

 be present. 



Number of Cells. The number of cells in different 

 samples of milk will vary very much. Milk from indi- 

 vidual cows in normal condition may contain from 50,000 

 to 1,000,000 and over per c.c. (Savage). Milk from 

 the same cow may show considerable differences when 

 examined at intervals of a week or a month, and varia- 

 tions may also be found in the milk from different quar- 

 ters of the udder of the same cow. The number of cells 

 may differ at different stages of the same milking, being 

 much greater in the end milk than in the first milk. 



The cellular content is very high for a few days after 

 calving. Near the end of lactation the cells again in- 

 crease in number, and they are also present in excess 

 after incomplete or delayed milking. In mastitis there 

 is usually a pronounced increase in the number of cells, 

 particularly the leucocytes. In some cases the number 

 is as high as 200,000,000 to 300,000,000 per c.c. (Sav- 

 age), but in others it is as low as 500,000 per c.c. The 

 cell content of milk from an udder affected with mastitis 

 exhibits two other features which are important, viz: 

 the cells are clumped or grouped together, and 75 to 80 

 per cent, are polymorphonuclear leucocytes. Red-blood 

 cells may also be present in the milk when the udder is 

 very much congested, as may occur at the beginning of 

 lactation and in acute inflammation, and also following 

 traumatic injuries. 



The differences in the cell content of the individual 



