450 BACTERIOLOGY. 



pressure obtained in this way is frequently not sufficient 

 to permit of the bulb being completely filled, and often 

 only a few drops of fluid can be obtained. To obviate 

 this the bulbs may be blown and allowed to cool, but 

 not sealed. After a sufficient number of them are pre- 

 pared 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, completely vaporized, over the 

 flame, and while the steam is still escaping the point is 

 sealed in the gas flame. All air will have thus been 

 replaced by water vapor, and if the point of the stem 

 be now broken off under water the bulb will fill quickly 

 and completely. It is not desirable to fill them com- 

 pletely, but rather to only about three-fourths of their 

 capacity, as when full it is difficult to empty them with- 

 out contaminating the contents. 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 pro- 

 cured 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 alco- 

 hol 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 recommeded by Kirschner. It 



