BACTERIOLOGICAL STUDY OF WATER. 495 



and often only a few drops of fluid can be obtained. 

 To obviate this bulbs may be blown and allowed to 

 cool, bat not sealed. After a sufficient number of 

 them are prepared they are taken, one at a time, and 

 gently warmed over the flame; while still warm the 

 extremity of the stem is dipped into distilled water 

 and held there until a few drops have passed up into 

 the bulb; this is then carefully boiled, or, rather, com- 

 pletely vaporized, over the flame, and while the steam is 

 still escaping the point is sealed in the gas-flame. All 

 air will thus have been replaced by water vapor, and if 

 the point of the stem be now broken off under the water 

 the bulb will fill quickly and completely. It is not 

 desirable to fill them completely, but rather to only 

 about three-fourths of their capacity, as when full it is 

 difficult to empty them without contaminating the con- 

 tents. They are emptied by gently warming over a gas 

 or alcohol flame. 



A number of them may be made, sealed, and kept on 

 hand. They are sterile so long as they are sealed, be- 

 cause of the heat that is employed in their manufacture. 



When a sample of water is to be taken, the point of 

 a bulb is simply broken off with sterilized forceps 

 under water at the place from which the sample is to 

 be procured and held there until the necessary amount 

 has been obtained. This may serve as a sample from 

 which to prepare plates or Esmarch tubes on the spot, 

 or the tip of the stem may be resealed in the flame of 

 an alcohol lamp, the bulb packed in ice, and transported 

 in this condition to the laboratory. 



Another very simple and useful device for collecting 

 water samples is that recommended by Kirschner. It 

 consists of a piece of glass tubing of about 5 or 6 mm. 



