METHODS OF INVESTIGATING BACTEBIA. 



807 



added to the various nutrient substrata. Attempts 

 carried out on those principles seem to promise useful 

 results, hut as yet this method has not heen sufficiently 

 tested. 



b. Water. The specimens to be investigated must be investigation 

 taken in sterilised vessels with glass stoppers, or, in order * 

 to avoid contamination which is very apt to occur during specimens, 

 the transport, in small glass bulbs devoid of air and sub- 

 sequently sealed. These glass bulbs have a diameter of 

 about 1^ cm., and are provided at 

 one side with a glass tube almost of 

 capillary thickness, and 10 to 15 cm. 

 in length.* By warming the bulb, 

 and subsequently immersing it in 

 distilled water it is about half filled 

 with water; it is then placed on a 

 stand, the glass tube being directed 

 obliquely upwards, and surrounded 

 with filter paper; the water in the 

 bulb is then brought to the boil, the 

 steam streams out of the capillary 

 tube, and any drops of fluid which 

 may be carried with it are soaked up 

 by the filter paper. When all the 

 water, with the exception of half a 

 drop, has been volatilised the capil- 

 lary tube is sealed while the stream 

 of steam is still passing. 



These tubes are carried in this state, 



and can be readily sent over considerable distances in tin 

 vessels with a wooden bottom in which two hollows are 

 present. In taking the specimen to be tested a solution of 

 sublimate (1 to 2,000) is poured over the bulb and the 

 hands of the experimenter, and then the sublimate is re- 

 moved by a portion of the water to be tested. When it 

 has been quite removed, the capillary tube is broken near 

 the point (at a) under water, which then rushes into and 

 fills the bulb. The tube is then sealed (at I) in the flame 



* These glass bulbs are readily prepared by means of a blow-pipe, 

 or they can be obtained from any glass manufactory at a price of from 

 3d. to 7(/. per dozen. 



Fig. 144. Apparatus 

 for collecting water. 



