SPOROGENES TEST. 5 



14 samples of milk examined in this manner it is evident as shown 

 in Table 1 that there may be a considerable variation in the results 

 obtained from a given sample. 



Table 1. — Variation in the Savage sporogenes test, showing number of positive 

 tubes of 2 c. c. each after incubating for 48 hours at 37° to 40° C. 





Number of positive tests. 



Range in 



Sample. 





number of 

 positive 













Setl. 



Set 2. 



Set 3. 



Set 4. 



Set 5. 



tests. 



1 



3 



5 



6 



3 



2 



2 to 6 



2 



4 







2 



1 



3 



0to4 



3 



2 



2 



1 







2 



0to2 



4 



1 



1 



1 











Otol 



5 



1 











1 



1 



Otol 



6 



1 



2 







1 



2 



0to2 



7 



2 



1 



2 



2 



1 



lto2 



8 



1 



2 



2 







2 



0to2 



9 



1 



















Otol 



10 



4 



4 



1 



3 



3 



lto4 



11 



9 



8 



5 



6 



7 



5 to 9 



12 



6 



8 



5 



6 



6 



5 to 8 



13 



7 



6 



3 



7 



6 



3 to 7 



14 



9 



8 



9 



7 



9 



7 to 9 



The sample of milk in every case was shaken thoroughly to give 

 as equal a distribution of spores as possible. The 2 c. c. samples 

 used in the sporogenes test were removed in two different ways : 

 (1) Ten 2 c. c. samples were removed from the sample of milk by 

 means of a sterile 2 c. c. pipette ; (2) ten 2 c. c. samples were removed 

 from the sample of milk by means of a sterile 10 c. c. graduated 

 pipette, successive 2 c. c. portions being delivered for each sample. 

 It was found that this variation in removal of the 2 c. c. samples 

 had no effect on the results of the sporogenes test. 



The effect of the variations in the numbers of positive tubes and 

 different sets of tubes of milk from the same sample of milk is ob- 

 vious when one attempts to grade the milk by the Savage method. 

 For example, in Table 1, Samples 2, 3, 6, 8, and 10 would be graded 

 as either good or unsatisfactory, according to the results of the 

 sporogenes test and the Savage arbitrary standards. This is shown 

 more clearly by consideration of the results obtained with Sample 2. 

 Each set of 10 tubes represents a complete sporogenes test according 

 to the Savage method. In Set 2 there were no positive tests and in 

 Set 4 there was one ; therefore, the milk would be graded by either of 

 these tests as good. In the other sets there were 2, 3, and 4 tubes 

 positive, which according to the standards would necessitate calling 

 the milk unsatisfactory. 



Two reasons at least may be designated as contributing causes for 

 the variations in the sporogenes test : First, uneven distribution of 

 the spores in the milk ; and, second, lack of development of the char- 

 acteristic stormy reaction on which the test is based. Savage (12) 

 mentions the fact that the lack of an even distribution of spores is a 



