V] METHODS OF INOCULATION 11 



and such water does not contain any of these organisms, are 

 absurd; the latter statement would be unjustified even if large 

 quantities of the water had been subjected to examination. 



For the detection of bacillus coli, bacillus of typhoid, and 

 a certain variety of proteus Zenkeri, a normal inhabitant of 

 sewage, the following method^ will be found to answer well : 

 Through a Berkefeld or Pasteur pressure filter a large vol- 

 ume of the water is pumped. The filter I generally use for 

 the purpose is a Berkefeld large bougie, which by a screw 

 can be well and tightly fastened into one end of a cylindrical 

 glass ; the metal tube projecting from the candle is fixed 

 through an indiarubber stopper into a large bottle holding 

 about i,ooo — 1,200 cc; this bottle has at the neck a lateral 

 glass tube, which by means of a stout indiarubber tube is 

 connected with an exhaustion pump, a good size hand- 

 pump. Before using the filter the candle, screw, indiarubber 

 stopper, glass cylinder, and glass bottle are all sterilised, the 

 glass and screw in the hot air-chamber, the candle and 

 indiarubber stopper in boiling water, in which the candle is 

 kept from half to one hour. 



The water to be examined is poured by means of a sterile 

 glass beaker into the glass cylinder, and exhausting the air 

 in the bottle the water filters easily and rapidly; 1,200 — 1,500 

 or 2,000 cc. are thus easily filtered in a moderate space of 

 time; 1,200 cc. pass through in about 15-20 minutes. 

 Then the candle is unscrewed carefully, taken out with clean 

 hands, and 10 cc. of sterile water (or of the filtered water 

 from the bottle) are measured into a sterile glass dish ; the 

 whole surface of the candle is well brushed into these 10 cc. 



^ 1 have practised this meLhodsince 1892 ; when with Dr. Theodore 

 Thomson the outbrealc of typhoid fever in Worthing, 1893, was 

 investigated, it was this method by which the typhoid bacillus in the 

 suspected water was demonstrated. 



