4 BULLETIN 940, IT. S. DEPARTMENT OF AGRICULTURE. 



varied slightty in that sterile paraffin was poured into each tube after 

 heating. This formed a plug over the milk, and it was not necessary 

 to place the tubes under anaerobic conditions. 



It was considered advisable to try the test on milk produced under 

 conditions that would represent the worst grade of milk which might 

 be encountered under commercial conditions. In order to do this, 

 four cows were placed in a small barn which had been used for simi- 

 lar experimental purposes. The loft above the cows was composed 

 of narrow boards laid from 1 to 2 inches apart. Hay and cobwebs 

 hung down from these openings. The walls were soiled with manure 

 and dirt. All the cows were allowed to become dirty and their 

 udders and flanks were more or less covered with partly dried ma- 

 nure. The manure was removed from the floor only twice a week. 

 Open pails, not sterilized, were used for milking. 



To show the relation between the Savage sporogenes test and the 

 milk, the sediment from 1 pint of milk, the total count, and the re- 

 sult of the Savage test are shown in Plates I, II, and III. In the 

 upper right-hand corner of each square is a number designating the 

 number of tubes showing a positive sporogenes test out of the 10 

 tubes used for each sample. Keeping in mind the arbitrary standards 

 set by Savage (that is, or 1 -f- = good milk, 2, 3, or 4 -f- = unsatis- 

 factory milk, 5 or more -j- = bad milk) the results are interest- 

 ing. It will be noted that according to this test the milk from 

 Samples 1 to 35, inclusive, would be called good milk. It is believed 

 that the sediment disks and counts make further discussion unneces- 

 sary. Particular attention is called to the difference in sediment be- 

 tween Sample 1 and Samples 19 and 20. None of the three showed a 

 positive test by the Savage method. On Plate III samples from 36 

 to 52, inclusive, would be classed as unsatisfactory by the Savage 

 sporogenes test. No one would dispute this statement, although 

 many were no worse than those called good on Plates I and II. 

 Samples 53, 54, and 55 are classed as bad by the test, yet they are no 

 worse than some called good. 



It is further evident from the results shown on the plates that there 

 is no relation between the sporogenes test as used by Savage and the 

 total count. In this connection it may be noted that the milk ex- 

 amined was fresh milk. Savage also found very little relationship 

 between the test and the total count. 



The question naturally arises in connection with the sporogenes 

 test as to the accuracy of the test itself. Will a number of tests with 

 a given sample of milk show the same results? To answer this ques- 

 tion, 5 sets of 10 tubes each, with 2 c. c. of milk in each tube, were 

 prepared from a sample of milk. In other words, the Savage method 

 was applied 5 times to the same sample of milk. From the results of 



