PATHOLOGY OF MILK 29 



general average of 19-2 pus cells in the field of the microscope. 

 Streptococci and other bacteria were present in large numbers. 

 The highest number of pus cells to any one cow was 158-5 in the 

 field of the microscope. Five cows only gave a percentage of o-i 

 pus cell to the field (as compared with 45 in the first group) ; only 

 12 cows out of this 100 gave an average of less than i pus cell to 

 the field ; only 38 gave an average of less than 5 pus cells ; and only 

 54 (as compared with 98 in the first group) gave less than 10 pus 

 cells to the field.^ 



From these results Stokes and Wegefarth were led to the obvious 

 conclusion that cows kept in the country under sanitary and 

 hygienic conditions are less capable of causing disease in persons 

 consuming their milk than cows kept in the city under the con- 

 ditions of group 3. They consider any standard for exclusion of 

 milk containing pus cells must of necessity be arbitrary, but recom- 

 mend that an aver^ige of more than 5 pus cells to the field of the 

 oil immersion lens should suffice to exclude the milk of such 

 animal. Taking i pus cell in the field as a standard, it would 

 appear that Stokes and Wegefarth found 25 per cent, of the milks of 

 country cows, kept under good conditions, and 88 per cent, of town 

 cows, kept under bad conditions, contained pus cells. Eastes, who 

 made an examination of 186 London milks, found pus cells 

 present in 30 per cent- Too much emphasis must not be laid 

 upon the difference between these results, as somewhat different 

 methods were adopted. The effect of drinking milk containing pus 

 is referred to subsequently. 



Mucous threads are commonly found in milk containing pus. 

 Such threads probably consist of nucleo-albumin, and when occur- 

 ring with pus cells, the condition of " muco-pus " is present. This 

 is held to indicate inflammatory- lesion of the ducts of the udder, 

 and not abscess formation in the substance of the gland. Blood 

 corpuscles are not rare in milk, particularly soon after lactation. 



The last and least important kind of cell is that of the epi- 

 theliiDn. Such scales may be derived either from the hand of the 

 milker or from the teats of the udder. Epithelial cells are large 

 and nucleated. 



Milk containing many blood cells, mucous threads, or leuco- 

 cytes, and milk containing any pus cells should be looked upon as 

 unfit for human consumption. 



* Jour, of State Med., 1897, vol. v., pp. 439-443. 



* Brit. Med. Jour., 1899, vol. ii., p. 1342. 



