CELLS IN MILK 741 



no formation of a surface scum ; the latter seems to protect the 

 bacilli. Kussell and Hastings l confirmed Smith's experiments 

 and assert that it is sufficient to heat milk to 60 C. (140 F.) in 

 a closed receptacle for a period of not less than twenty minutes in 

 order to destroy the tubercle bacillus. The surface scum forms 

 on milk only when it is heated in contact with air ; all pasteurisers, 

 therefore, should be closed vessels. The author has devised a 

 simple form of domestic pasteuriser, which is made by Messrs. 

 Allen and Hanbury. 



The occurrence of so-called leucocytes and pus-cells in 

 milk must be considered. A certain number of cells 

 resembling polymorphoriuclear leucocytes are always 

 present in milk, more numerous during the first week of 

 lactation, and then accompanied by colostrum corpuscles. 

 An excess of these cells may indicate some local inflamma- 

 tory affection of the udder, or, if streptococci and blood 

 are present in addition, suppuration, but not necessarily, 

 for Russell and Hoffmann, and Revis have shown that 

 a very large cell count (500,000-1,000,000, or even 

 10.000,000, per cubic centimetre) may often be obtained 

 from quite healthy cows. The nature of these cells has 

 been the subject of an extended investigation by Hewlett, 

 Villar, and Revis. 2 Their conclusion is that the majority 

 of these cells are not leucocytes, but are germinal cells of 

 the secreting epithelium of the udder. Blood may also 

 be present transitorily in health (Revis) ; a few red cor- 

 puscles are probably present in all milk. The presence of 

 squamous epithelial cells indicates desquamation from 

 the teat or udder or from the hand of the milker. 



There is no doubt that micro-organisms are far more 

 abundant in milk as supplied to the consumer than should 

 be. This arises from the ignorance and carelessness of 

 those charged with the duty of providing and distributing 

 this important article of diet. The udder and teats of 



1 llth Ann. Rep. Wisconsin Agricult. Exp. Station. 



2 Journ. of Hygiene, vols. ix, x, xi, and xiii. 



