THE SANITARY FACTORS 99 



been pasteurized, and the sediment test fails af er clarifica- 

 tion. 



To overcome these difficulties is the purpose of the B. 

 sporogenes determination as an indicator of manurial pollu- 

 tion as proposed by Weinzirl and Veldee.* B. sporogenes 

 is an intestinal organism, and hence indicates manure when 

 found in milk; it does not multiply at ordinary temperature 

 at which milk is held, and so it truly indicates the pollution 

 even of milks kept for varying periods of time and at varying 

 temperatures; it produces spores but these are not killed 

 by pasteurization; and, finally, the organism can be easily 

 and quickly determined. 21 



Thus far most of the work of health authorities on 

 the dirt question has been concerned with visible dirt 

 as disclosed by the sediment tester.f (See Plate 4.) 

 The method is simple and is effective for demonstra- 

 tional purposes. Its weakness, on the other hand, has 

 been pointed out above. The B. sporogenes test is 

 already known in water bacteriology, and its develop- 

 ment in relation to milk is to be viewed with interest. 



Dirt t or Sediment, Tests and Bacteria Counts. To 

 avoid possible confusion it is well to note that, as im- 

 plied by Weinzirl and shown by recent experiments, 22 ! 

 the quantity of sediment or visible dirt caught on the 

 disk by the straining tests is no criterion of the bacteria 

 count of the milk. High-bacteria milks may by these 



* Am. Jour. Public Health, 1915, Vol. V, p. 862. 



t There are several varieties of these. The New York City Health 

 Department requires the test to be applied in all creameries shipping 

 milk to the city, and has established a standard for use in determining 

 whether milk contains excessive dirt. (Regulations, March 30, 1915.) 



I In these experiments (in the U. S. Department of Agriculture) the 

 Lorenz apparatus was found the most convenient and practical. 



