282 



The Phagocytic Power of the Blood 



The blood to furnish the serum is taken in a small bent tube shown 

 in the illustration. 



The blood from the puncture is allowed to flow into the bent end 

 of. the tube, into which it enters by 

 capillary attraction and from which it 

 descends to the body of the tube by 

 gravity. At least i cc. of the blood is 

 required to furnish the serum. The 

 ends of the tube are closed in the 

 flame and the tube stood in the ther- 

 mostat for fifteen to thirty minutes. 

 Coagulation takes place almost im- 



Fig. 94. — Special blood pipette (Miller). 



mediately, and the serum usually sepa- 

 rates, quickly. If it does not do so, 

 Wright recommends hanging the curved 

 arm of the tube over the centrifuge tube 

 and whirling it for a moment or two, 

 when the clot is driven into the straight 

 arm of the tube and the clear serum 

 appears above. The tube is then cut 

 with a file so that the serum can be 

 removed when needed. Mixing the factors concerned in the test is 

 a matter that requires practice and a steady hand. It is best 

 done, as recommended by Wright, in a capillary tube controlled 



Fig. 95. — Opsonizing pipette 

 containing blood-corpuscles, 

 bacterial emulsion, and blood- 

 serum (Miller). 



