BACTERIA FILTERS 



161 



ing a bacteria-free toxic liquid or with some other object in view the 

 filtrate must always be tested to find out whether any bacteria are 

 present. This is done by inoculating from the filtrate solid culture 



FIG. 86 



Apparatus for the rapid filtration of toxins, etc.: a, filter flask; 6, Woulfe bottle to guard 

 against regurgitation of water from the pump; c, reservoir for the filtrate; d, water vacuum pump. 

 (McFarland.) 



FIG. 87 



FIG. 88 



Chamberland filter. 



11 



Brass suction pump: a, connection to faucet; d, con- 

 nection for rubber tube from filtering apparatus; 

 c, valve to prevent regurgitation of water to filter. 



