14 CLINICAL BACTERIOLOGY 



it will be found good practice to centrifugalize the urine in 

 a large tube first, then pipette the top fluid, leaving about 

 1 c.c. ; this or less may be placed in a small precipitating 

 tube and centrifugalized. By this process a greater con- 

 centration is obtained. 



Centrif ugalizing Milk. — Milk may be centrifugalized for 

 the purpose of isolating a variety of bacteria, and, of course, 

 the most important in cow's milk is the bacillus of tuber- 

 culosis so far as veterinary surgeons are concerned. 



Mix 20 c.c. of milk with 1 c.c. of a 50 per cent, solu- 

 tion of potash, heat in a water-bath until the solution turns 

 brown, add 20 c.c. of acetic acid. Shake the whole well, 

 heat in water-bath for two minutes, and centrifugalize for 

 ten to fifteen minutes. 



The top fluid is now poured off ; add 30 c.c. of hot water 

 to the sediment and centrifugalize ; pour off the super- 

 natant fluid, and make smears on three slides ; fix, stain, 

 and examine. 



