SUMMARY. 137 



It would be well to study the milk of individual cows, prefer- 

 ably with known histories, with reference to the occurrence of 

 leucocytes and streptococci. For leucocytes the Doane- Buck- 

 ley test might be used, and for streptococci, numerical deter- 

 minations. Histological examination of the udder may prove 

 to be a reliable criterion for the determination of disease in 

 experimental work. 



The situation is very well summed up in the Preliminary 

 Statement by the Committee on Standard Methods of Bacterial 

 Milk Analysis to the Laboratory Section of the American Pub- 

 lic Health Association, in these words : 



"Since, however, evidence already collected, warrants beyond all 

 question the general statement that these cells frequently do not have the 

 significance that has been attached to them by many observers, it would 

 perhaps be more fair to all parties concerned to use this (leucocyte) test 

 at present as a means of detection only, and not to condemn the supply 

 unless physical lesions are demonstrated. The standards so far 



chosen have been more or less arbitrarily selected on what appears as 

 rather inadequate data, and from a comparison of results it is apparent 

 that much more comparative work needs to be done." (8) 



The committee expresses* a similar view in its 1908 report as 

 follows : 



' ' It is the opinion of the Committee that milks having high leucocyte 

 content, unless accompanied by other indications of inflammation such 

 as blood or virulent organisms, should not be condemned as unfit for use 

 on the laboratory findings alone. Such milks may be regarded with sus- 

 picion and the laboratory findings may well serve as a guide for veteri- 

 nary inspection. " (9) 



The writer rather doubts whether microscopic examination 

 of milk will eventually prove a satisfactory means of protect- 

 ing the public from streptococci in milk from diseased cows. 

 When a satisfactory decision has been reached as to w r hat con- 

 stitutes a diseased udder in a cow and how to detect the pres- 

 ence in a herd of animals so affected, there remain administrative 

 difficulties. The individuals in a dairy herd are constantly 

 changing and the health of the udder is liable to variation from 

 day to day, which necessitates very frequent examinations. 

 Then there remains the difficulty of enforcing the exclusion of 

 the milk of the condemned cow. A large American city of to- 





