BACTERIOLOGICAL PIPETTES. 



using a rubber bulb, such as comes on medicine droppers, \ve have a 

 means of sucking up and forcing out fluids by pressure with the thumb 

 and forefinger of the right hand. The bulb should be pushed on about 

 1/2 to 3/4 in.; this gives a firmer surface to control the pressure on 

 the bulb. 



FIG. 6. i, 2, 3, Drawing out glass tubing; 4, 5, Wright's rubber bulb capillary 

 pipettes showing grease pencil mark for making dilutions; 6, 7, Wright's U tubes; 

 8, 9, 10, Methods of drawing out test tubes for vaccines in opsonic work; n, Bac- 

 teriological pipette. 



A bacteriological pipette is made by drawing out a nine-inch piece 

 of tubing about three inches at either end, then heating in the middle 

 we draw out and have two pipettes similar to the one shown in the 

 drawing. A piece of cotton is loosely pushed in just above the narrow 

 portion. These may be wrapped in paper and sterilized for future 1 

 use. They may be made perfectly sterile at the time of drawing out. 



Where gas is not at hand, the Barthel alcohol lamp gives a flame 

 similar to that of the Bunsen lamp and is equally satisfactory for 

 heating glass tubing. 



