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 
