METHODS OF CULTIVATION OF BACTERIA. 



is arranged as in Fig. 39. The fluid to be filtered is placed in 

 the cylindrical vessel a. Into this a " candle " or " bougie " of 

 porcelain dips. From the upper end of 

 the bougie a glass tube with thick rubber 

 connections, as in Fig. 39, proceeds to 

 flask b and passes through one of the two 

 perforations with which the rubber stop- 

 per of the flask is 'furnished. Through 

 the other opening a similar tube proceeds 

 to the exhaust-pump. When the latter is 



FIG. 39. Chamberland s 

 candle and flask arranged for 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. 40). On this 



the narrow end of the funnel d, which 



must, of course, be of an appropriate 



size, rests. A broad band of sheet 

 rubber is then wrapped 

 round the lower end of 

 the funnel and the pro- 

 jecting 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 



S ? aCe '. and is Sufcked thr0 "S h int the flask b - 

 rubber stopper for (2) This modification is shown in Fig. 41. Into 



F^ e 39. UrP SeaSin the narrow P art of the funnel an india-rubber 

 stopper is fitted, which has a perforation in it 

 sufficiently large to receive the candle, which it should grasp 

 tightly. 



FlG. 40. Chamberland's bou- 

 gie arranged with lamp funnel for 

 filtering a small quantity of fluid. 



