594 SAOTERIOLOOY. 



the bulb will fill quickly. It is not desirable to 

 fill them completely, but rather to only about three- 

 fourths of their capacity, as when fuU it is difficult 

 to empty them without contaminating the contents. 

 They are emptied by gently warming over a gas or 

 alcohol flame. 



A number of bulbs may be ma9^, sealed, and kept 

 on hand. They are sterile so long as they are sealed, 

 because of the heat 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 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 trans- 

 ported in this condition to the laboratory. 



Another very simple and useful device for collecting 

 water samples is that recommended by Kirschner. This 

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

 inside diameter, and 36 cm. long, bent in the form of 

 a U, with either extremity of the arms bent again at 

 right angles in the same plane and drawn out to a point 

 and sealed. Such tubes are sterilized in the flame as they 

 are made. The sample is collected by breaking off 

 both points, immersing one of them in water and suck- 

 ing on the other until the tube is filled. Then both 

 points are again sealed in the flame and the tube packed 

 in ice. The objection to this tube is the danger of con- 

 taminating its contents with saliva during the act of 

 filling by suction, though this danger is not so great 

 as might at first appear, as we shall learn in our efforts 

 to cultivate bacteria from the mouth-cavity. 



