TESTS FOR CELLULAR CONTENT OI' MILK. 131 



Expression of RjvSui.ts. 



All results should be expressed in numbers of cells per cubic centime- 

 ter of the orig-inal milk, and in order to avoid fictitious accuracj-, should 

 be given in accordance with the method adopted b>- the Committee on 

 Standard Methods of Water Analysis, as reported in this Committee's 

 report to the Ijaboratory Section of the American Public Health Associa- 

 tion for 1905, page 94. 



The test has been shown to give results, on duphcate deter- 

 minations, with a percentage variation of only about b'i( (23). 

 Thus we have a test of excellent precision that already has 

 added valuable facts to the knowledge of the subject of leu- 

 cocytes in milk. 



The test has not been widely applied in practice, because of 

 the difficulty in fornudating a standard. A cellular content 

 varying from 100,000 to 400,000 jjer cc. is connuon in normal 

 cows, and even counts of 1,000,000 ])er cc. are encountered. 

 A series of determinations of the leucocytes in the milk of 102 

 healthy cows showed an average of 241,000 per cc. Thi-^ 

 range of counts considerably overlaps the range of counts e.x- 

 hibited by cows with noticeable" udder trouble. 



Under the circumstances, the milk of a diseased cow witli a 

 count of a few millions is so diluted in the milk of the healthy 

 cows showing relatively high counts, that the leucocyte con- 

 tent of the mixed milk is not raised. 



Savage s test. Savage (25) has de\-eloped a ver\- similar test. 

 One cc. of milk is diluted with 20 cc. of Toisson's fluid and 

 centrifugalized for ten minutes at about 1,800 revolutions iier 

 minute. The cream is then agitated with a glass rod and the 

 whole again centrifugalized for ten minutes, and the super- 

 natant fluid is drawn off to the 1 cc. mark. The remaining 

 1 cc. is thoroughly mixed and the number of leucocytes deter- 

 mined by the use of the Thoma-Zeiss blood counter. This, 

 like the Doane-Buckle\- test, shows high numbers of leucocytes, 

 and the same difficulties in setting a standard are encountered. 



Trommsdorji^s test. Trommsdorff i^U, 30, 31 ) arrives at con- 

 clusions regarding the number of cells in milk by measuring the 

 amount of sediment obtained by centrifugalizing. Five cc. of 

 mixed milk is centrifugalized for some minutes at 1,200 revolu- 



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