SPOROGENES TEST. 19 



ditions. This has been emphasized in the discussion of the test in 

 connection with certified milk and dirty milk, and is again illus- 

 trated by the results shown in the last two sections of Table 6. 



SUMMARY AND CONCLUSIONS. 



1. The Savage test using 10 tubes with 2 c. c. of milk is not suffi- 

 ciently delicate to be of great value, evidently, because not enough 

 milk is used in each tube. 



2. The Weinzirl test does not appear to correlate with the quantity 

 of manure in milk. This seems to be due both to the method of 

 making the test and to the variation in spore content of B. enteritidis 

 sp or o genes in manure. 



3. The experiments indicate that the majority of spores of B. 

 enteritidis sporogenes gain entrance to milk by means of cow manure. 



4. With 10 tubes and 20 c. c. of milk to each tube, the sporogenes 

 test as used throughout the experiments shows a fairly definite rela- 

 tion to conditions of production. This relation is more definite than 

 that shown by either the Savage or the Weinzirl test. 



None of the tests, however, show a definite correlation between 

 the number of tubes positive and the quantity of manure in any given 

 sample. But with 20 c. c. quantities of milk and discounting indi- 

 vidual variation, there is a general trend of agreement between the 

 test and manure. 



5. As a rule, the sporogenes test with 10 tubes and 20 c. c. of milk 

 shows high results, that is, a large number of positive tubes with 

 milk produced under dirty conditions. With milk produced under 

 clean conditions, the test is apt to be negative or show only a few 

 positive reactions. 



The test tends to differentiate between extremes in methods of pro- 

 duction, and naturally most milk will fall between these limits. The 

 nearer the conditions of production approach one extreme or the 

 other, the more accurately will the sporogenes test indicate the con- 

 ditions. 



It must be pointed out, however, that no reliance can be placed on 

 one test with one sample. Individual variation with a single test 

 makes a series of tests on a number of samples necessary for the 

 result to have any significance. 



6. When the limitations of the test are understood and the results 

 properly interpreted, its use with a series of samples from a given 

 source should give considerable information as to cleanliness of pro- 

 duction, particularly in connection with the extent of manurial pol- 

 lution. The test, if used, however, should be taken as merely an indi- 

 cation of the conditions of production, and should be verified by an 

 actual inspection at the farm. 



