14 BULLETIN 940, U. S. DEPARTMENT OF AGRICULTURE. 



ures. It is apparent that there is not a very great range left to cover 

 the results obtained in the examinational" the intermediate grades of 

 milk. From these results, however, it seems probable that the spo- 

 rogenes test, using 10 tubes of 20 c. c. quantities of milk for each tube, 

 may be of some value in determining whether milk has been produced 

 under clean or dirty conditions. One test, however, would probably 

 not be sufficient to enable one to make this decision. If several tests 

 were made and the great majority of the results were either high or 

 low, the results could be interpreted more accurately and the value 

 of the test would be greatly improved. 



It is impossible to say from these results where milk produced under 

 fair conditions would fall according to this grouping. The tendency 

 would be for such samples to show great variations, some falling into 

 the clean grade, others into the dirty grade. 



CONDITIONS OF PRODUCTION OF PASTEURIZED MILK AS 

 INDICATED BY THE SPOROGENES TEST. 



In connection with the results just discussed it will be of interest to 

 see what commercially pasteurized milk showed, using this test to in- 

 dicate conditions of production. This is possible, because the test is 

 probably a nonmultiplying one, as shown by the work of Savage (12) . 

 To verify this point several experiments were conducted by holding 

 pasteurized milk at room temperature for 24 hours. No change in 

 the number of spores was observed other than what could be accounted 

 for by the limitations of the test. 



Since the spores are not destroyed by the usual pasteurizing tem- 

 peratures and do not change in number, the sporogenes test, if it 

 correlates with the presence of manure or with the general conditions 

 of cleanliness in production, should, as suggested by Weinzirl, be an 

 excellent test for determining the quality of the raw milk before pas- 

 teurization. The results which are shown in Table 5 were on the 10 

 c. c. and 10-tube basis, because the samples of milk were examined be- 

 fore the value of 20 c. c. quantities of milk was known. When examin- 

 ing the results it should be kept in mind that certified milk shows 

 negative results with this quantity of milk. Consider, now, the re- 

 sults of the sporogenes test with dirty milk shown at the bottom of the 

 table, and what can then be said of the conditions under which the 

 raw milk was produced. 



