PIPETTES 



35 



for collecting blood when the serum has to be examined, and 

 have quite replaced the pipettes described above. They can 

 be prepared easily after a little practice, or may be bought 

 from R. B. Turner, n, Foster Lane, E.G., at a moderate price. 



A Wright's blood capsule consists of a piece 

 of glass tubing which is drawn out straight to 

 a narrow point at one end, whilst the other, 

 also drawn out to a point, is curved round 

 parallel with the main tube in the shape of a J 

 (Fig. n). To use it, proceed as follows: 

 Prick the patient's ear, or, if you prefer it, the 

 finger (after the application of a wide india- 

 rubber band), and squeeze out a large drop of 

 blood. Place the tip of the curved end of the 

 pipette in this drop, holding the pipette with 

 the straight end pointing upward (Fig. 12), 

 and you will find that the blood will run 

 rapidly into the curved tube by capillary at- 

 traction; continue to squeeze out more blood 

 and to suck it up until you have collected as 

 much as you want. It should be quite easy to get the pipette 

 half full. Then gently warm the tapering portion of the 

 straight end of the pipette in a spirit-lamp or match-flame, 



FIG. ii. (About 

 full size.) 



FIG. 12. 



and afterwards seal the tip (Fig. 13). As the air which is now 

 imprisoned in the upper part of the pipette contracts it will 

 suck the blood from the curved limb into the body of the 



