82 METHODS OF CULTIVATION OF BACTERIA. 



proceeds to the exhaust- pump. When the latter is put 

 into action the fluid is sucked through the porcelain and 

 passes over into flask b. This apparatus is very good, but 

 not suitable for small quantities of fluid. 



(b) A very good apparatus can be arranged with a lamp 

 funnel and the porcelain bougie. These may be fitted up 

 in two ways, (i) An india-rubber washer is placed round 

 the bougie c at its glazed end (vide Fig. 31). On this the 

 narrow end of the funnel d, which must, of course, be of 



FIG. 31. Chamberland's 

 bougie arranged with lamp funnel 

 for filtering a small quantity of 

 fluid. 



FIG. 32. - 

 Bougie inserted 

 through rubber 

 stopper for same 

 purpose as in 

 Fig. 31. 



an appropriate size, rests. A broad band of sheet rubber 

 is then wrapped round the lower end of the funnel, and the 

 projecting part of the bougie. It is firmly wired to the 

 funnel above and to the bougie below. The extreme point 

 of the latter is left exposed, and the whole apparatus, being 

 supported on a stand, is connected by a glass tube with the 

 lateral tube of the flask b ; the tube a is connected with the 

 exhaust-pump. The fluid to be filtered is placed between 

 the funnel and the bougie in the space , and is sucked 

 through into the flask b. (2) This modification is shown 



