I CONTENT OF COW'S MILK 13 



The earlier stages of pregnancy do not influence the 

 number of leucocytes, but in the later stages, when the milk 

 is diminishing, a rise in the number of cells almost always 

 takes place, the rise being mainly in the large cells. The 

 milk of cows " drying off " is of high cellular content. 



In pathological conditions of the milk-producing apparatus, 

 there is a marked increase in the cellular content of the milk, 

 and numbers as high as 200,000 to 300,000 per cubic milli- 

 metre have been recorded by the writer in cases of garget. 

 In inflammatory and other pathological conditions it is par- 

 ticularly the polymorphonuclear elements which are increased. 

 They usually then form 75 to 80 per cent of the whole. 



An increase in the cellular or leucocyte content of the 

 milk, as it is usually called, may also be due to some old 

 pathological lesion of the udder or teats, all traces of which 

 had passed away at the time of examination as far as clinical 

 ■methods are concerned. The following may be quoted as an 

 instance : 



Cow No. 46. — Leucocyte count of the four mixed quartei-s 

 = 1025 per cubic millimetre. No local physical signs on 

 examination, but a very definite history of so-called " milk- 

 fever," involving the E.H.Q. (right-hind quarter) only, at 

 the time of last calving some months previously. At that 

 time this quarter was said to have been painful, and yielded 

 no milk. Examined a few days after the mixed milk sample 

 was taken, the milk from the individual quarters showed the 

 following results : 



E.F.Q. = 280 leucocytes. 

 R.H.Q. = 2250 

 L.F.Q. = 28 

 L.H.Q.= 64 



Hewlett, Villar, and Eevis ^ found that in general, in the 

 case of any particular cow, apart from changes produced by 

 some special causes, the number of cells per c.c. is fairly 

 constant over the lactation period. These investigators have 

 more recently classified the cellular elements found in milk. 

 They distinguish three common varieties, which they speak 

 of as large imi-nucleated cells, multi-nucleated cells, and small 

 uni-nucleated cells, and which closely correspond with the 

 1 Journal of Hygiene, 1909, vol. ix. p. 271 ; and 1910, vol. x. p. 56. 



