12 MILK AND THE PUBLIC HEALTH chap. 



deeply, and from its twisted shape frequently appears like 

 several nuclei. 



(h) Large Cells. — These cells vary greatly iu size, but are 

 usually large, their average diameter being from 13/t to 16yu., 

 but they may be as large as 24/^. They have a single nucleus 

 which occupies only a relatively small proportion of the cell. 

 All gradations between these cells and lymphocytes are met with. 

 (c) Lymphocytes. — Considerably smaller. They show great 



variability in size, in some 

 cases being quite small, 

 but for the most part 

 they have a diameter of 

 about 5-7/4. They are 

 circular or nearly so ; the 

 ^^ ( i ' '^f'^^j { nucleus stains deeply and 



^^ \ I , ^j occupies nearly the whole 



of the cell. 



The cellular content 

 of milk shows considerable 

 variation, even with appar- 

 ently perfectly healthy 

 cows. The writer has met 

 with variations ranging 

 from 50 to considerably 

 over 1000 cells per cubic 

 mm. As regards physio- 

 logical conditions, he found 

 that the age of the cow 

 and the previous number 

 of calves had little or no 

 influence upon the number, while, excluding animals which 

 had only calved within a few days, there was no relationship 

 between the number and the period since calving. In the 

 milk of cows examined within a few days after calving, there 

 is a marked increase in the cellular content, the increase 

 being especially in the lymphocytes. 



The milk secreted within a few days after parturition is 

 called colostrum. It is yellow and viscid with a strong 

 odour, and coagulates on boiling. It contains cells laden with 

 fat globules, the so-called colostrum bodies. 



Fi«. 2. 



