DIRECT EXAMINATION 



37 



B 



--/Occ. 



-Ice. 



\J 



Fig. 2. Fig 3. 



Fig. 2. — Kitasato filtering outfit ready to be attached to the exhaust pump. 

 A two-opening flask or bottle is interpolated to receive the backflow water, should 

 there be any. Various types of clay bougies may be used with this filter. The 

 rubber tubing for the connection must be heavy so as to prevent collapse by the ex- 

 haust pressure. — (Pitfield.) 



Fig. 3. — Special centrifugal tube {A) for concentrating bacteria and other micro- 

 organisms in liquids and also used in isolating or separating motile bacteria from 

 those which are not motile, as is explained under water analysis. The tube has a 

 capacity of 15 cc. with i cc. and 10 cc. marks. The tube is in two parts. The lower 

 narrowed end, having a capacity of i cc, is attached to the larger part by means of 

 a rubber-band ring. Centrifugalization is done at high speed. After centrifugali- 

 zation, the i cc. tube is removed and the contents thoroughly mixed by means of a 

 platinum wire loop. To avoid loss of the contents of the tube during the mixing, 

 attach the rubber ring. After the mixing the material is ready for the microscopical 

 counting and other examination. 



A suitable stopper attached to a brass or other metal rod {B) may be inserted 

 into the narrowed portion of the upper part of the tube in order to prevent mixing 

 of contents when removing the i cc. tube. These tubes will also be found useful 

 in measuring the amount of sediment in milk, water and other liquids. For this 

 purpose the i cc. portion should be graduated into tenths and hundredths. 



