38 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



several pipettes half full cannot be collected from a single slight 

 puncture. 



Many pathologists prefer the finger. In that case an excellent 

 needle can be made by softening a small piece of capillary tubing 

 in the flame and separating the two ends rapidly. This will give 

 two tapering tubes, which can be broken off so as to leave a very 

 sharp point, with which the skin at the side of the nail can be 

 punctured almost painlessly. The ligature is then applied as in 

 the figure, and the patient bends his finger forcibly, squeezing 

 out two or three drops of blood. After these have been collected 

 the bandage must be removed and the hand allowed to hang 

 down, so that the finger refills with blood. It is rebandaged and 

 rebent, and more blood obtained. If a relatively large amount of 

 blood is required (as in the Wassermann test) it is a good plan to 

 soak the hand in very hot water before applying the bandage. This 

 process should be learnt, since it is the simplest one by which 

 the practitioner can obtain blood from himself, as is often neces- 

 sary in opsonic work. 



