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 examination of 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 21 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. 
