A BRIEF NOTE ON THE USE OF GENTIAN VIOLET 

 IN PRESUMPTIVE TESTS FOR B. COLI IN 



MILK WITH REFERENCE TO 

 ; SPORULATING ANAEROBES 



IVAN C. HALL and LILLIAN JORDAN ELLEFSON 

 From the Hearst Laboratory of Pathology and Bacteriology, University of California 



Received for publication June 25, 1917 



In the case of milk, as formerly in the case of water, quali- 

 tative bacteriological standards have been preceded by quanti- 

 tative methods of evaluation, a trend of evolution just opposite 

 to that usual in science. The main reliance has been upon the 

 plain agar plate count though this is now professedly inferior to 

 the lactose agar plate for approximating the total aerobic plate 

 count as recently shown by Sherman (1916). But these plat- 

 ing methods take no cognizance of anaerobes and other bacteria 

 whose particular metabolic requirements happen not to be met 

 by the conditions set, and so the most recent Standard Methods 

 for Bacteriological Analysis of Milk (A. P. H. A. 1916) tend to lay 

 emphasis upon the method of direct microscopic examination, 

 the literature of which has been so adequately reviewed and 

 the technic perfected by Breed and Brew (1916). 



While appreciating the fact that the bacterial flora of milk is 

 well known and that qualitative examinations are frequently 

 made when searching for the cause of specific abnormalities in 

 milk we note that such examinations have not as yet become a 

 part of our routine procedure. 



In Cahfornia, however, the recent passage of laws (Cal. 1915) 

 effective October 1, 1916, prohibiting the sale without pas- 

 teurization of milk from cows not shown to be free from tuber- 

 culosis by the tuberculin test, has suggested the presumptive 

 test for B. coli as a criterion of unsuccessful operation of the 

 pasteurizing apparatus, the presence of this organism being 



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