42 BACTERIOLOGICAL DIAGNOSIS. 



in the collection of specimens. Suppose, for instance, 

 we wish to take some blood from a heart at a post- 

 mortem examination for investigation at a distance. 

 A point on the surface of the heart is first seared with 

 a hot iron to destroy any germs which might be present, 

 and the end of the pipette (still sealed) is thrust through 

 into one of the cavities. It is then broken off by dex- 

 terous pressure against the heart-wall, and the pipette 

 will fill slowly with the blood. Another method is to 

 break off the tip of the pipette and to warm the bulb 

 before making the puncture. The fluid will rise as the 

 bulb cools; or both ends may be broken up and the fluid 

 drawn into the bulb by gentle suction. 



Under any circumstances both ends of the pipette 

 must be sealed up in a flame (the flame of a wax match 

 will answer at a pinch) and the tube labelled. 



Another variety of pipette which is much used for the 

 transmission of blood, for the purpose of testing the 

 serum reaction for typhoid fever, is drawn out to a 

 point at one end only, the other being left wide and 

 separated from the bulb by a constriction (fig. 12 b). 

 The open end should be loosely plugged with cotton- 

 wool, and serves as a mouthpiece. The manufacture of 

 these pipettes presents a little difficulty, but a small 

 amount of practice will enable the practitioner to turn 

 out a perfectly serviceable one on occasion. These 

 pipettes are not so suitable as the others for the trans- 

 mission of fluids for cultural examination or injection 

 into animals. 



