EXPERIMENT STATION BULLETINS. 



337 



SAMPLE IV. 



*No serious attempt was made to differentiate the types of bacteria in this sample until the 

 SOth hour. 



COMBINATION IVb AND IVx. 



Dilutions employed for inoculating milk flasks. 



Culture IVb 1 : 10,000 



Culture IVx 1 : 100,000,000 



Number of bacteria, IVb, introduced into milk flask IVb = 114,000. 

 Number of bacteria, IVx, introduced into milk flask IVx = 23. 



Number of bacteria, IVb and IVx, introduced into milk flask IVb + IVx = 114,000 

 + 23 = 114,023. 



Changes in milk flasks apparent to eye. 



Milk flask cultures prepared Monday 9 a. m. 

 7 hours after inoculation, Monday, 4 p. m. 



IVb — unchanged. 



IVb + IVx — unchanged. 



IVx — unchanged. 

 24 hours after inoculation, Tuesday, 9 a. m. 



IVb — unchanged. • 



IVb + IVx — unchanged. 



IVx — unchanged . 

 31 hours after inoculation, Tuesday, 4 p. m. 



IVb — litmus slightly reduced. 



IVb + IVx — litmus nearly wholly reduced. 



IVx — unchanged . 

 48 hours after inoculation, Wednesday, 9 a. m. 



IVb — no further change. 



IVb + IVx — litmus wholly reduced. 



IVx — litmus pink. 

 55 hours after inoculation, Wednesday, 4 p. m. 



IVb — no further change. 



IVb + IVx — litmus reddened soniewliat. 



IVx — loppcring. 



Acid developed during changes. 

 Time after inoculation. 



Culture IVb 



Culture IVb + IVx.. . , 

 Culture IVx 



hrs. 

 14° 

 14° 

 14° 



7 hrs. 24 hrs. 31 hrs. 48 hrs. 55 hrs. 



14° 14° 17° 17° 15° 



14° 14° 17° 27° 36° 



14° 14° 14° 28° 50° 



43 



