232 



STATE BOARD OF AGRICULTURE. 



No. of micro- 

 organisms. 



3. 



6. 



9. 

 29. 

 30. 



32. 

 38. 

 43. 

 44. 

 45. 



46. 



48. 



60. 



62. 



107. 



112. 

 115. 

 116. 

 117. 



100° 

 for 20 

 min. 



5. The Effect of Sudden Cooling After Pasteurization Upon 



the Species Isolated. 



It lias been stated by certain writers that sudden cooling was essential 

 to stun the bacteria. Others say that if the cooling is rapid enough to 

 stay the multiplication of bacteria, that is all that is required. To gain 

 the real value of sudden cooling upon the milk bacteria isolated, the 

 author selected six varieties showing the widest differences for this test. 



Bouillon cultures were made and allowed to stand a few days for spore 

 formation, then they were subjected to Pasteurization. After Pasteur- 

 ization, one tube of each species was cooled suddenly to 8° C. [46° F.] 

 and one tube was allowed to cool to the temperature of the room grad- 

 ually. As soon as each had reached its desired temperature, fresh sterile 

 bouillon was inoculated, one tube from each and three platinum loopfuls 

 for each tube. They were placed away side by side at room temperature 

 for development. When there were the first traces of growth, the time 

 was noted. Five tests of each variety were made in this manner and the 

 results noted as in the following table: 



* Cultures— refers to the age of the culture used in Pasteurization. 



(■ Controls— cultures made at the same time as those Pasteurized but put away for development. 



j Cooled— cultures Pasteurized and suddenly cooled. 



U Non-cooled— cultures Pasteurized and allowed to cool gradually. 



