BLOOD PIPETTES II 



snapping off the sealed point of the capillary portion. 

 If pressure is now exerted upon the elastic bulb by a 

 finger and thumb whilst the capillary end is below the 

 surface of the fluid to be taken up, some of the 

 contained air will be driven out, and subsequent relax- 

 ation of that pressure (resulting in the formation of a 

 partial vacuum) will cause the fluid to ascend the 

 capillary tube. Subsequent compression of the bulb 

 will naturally result in the complete expulsion of the 

 fluid from the pipette (Fig. 1 4) . 



FIG. 14. Filling the capillary teat-pipette. 



A modification of this pipette, in which a constric- 

 tion or short length of capillary tube is introduced 

 just below the plugged mouth (Fig. 13, b), will also be 

 found extremely useful in the collection and storage 

 of morbid exudations. 



A third form, where the capillary portion is about 

 4 or 5 cm. long and only forms a small fraction of the 

 entire length of the pipette (Fig. 13, c), will also be 

 found useful. 



"Blood" Pipettes (Fig 15). Special pipettes for 

 the collection of fairly large quantities of blood (as 

 suggested by Pakes) should also be prepared. These 

 are made from soft glass tubing of i cm. bore, in a 

 similar manner to the Pasteur pipettes, except that 



