OBTAINING LARGE AMOUNTS OF HUMAN BLOOD 



33 



the treatment of syphilis is being guided by the Wassermann reaction, 

 frequent tests are necessary, and a patient may object to submitting to 

 repeated venipuncture. The method for securing blood just described 

 is so simple and efficient that objections to it are never made. 



5. Blood may also be drawn in a Wright capsule, made by drawing 

 out ordinary thin glass tubing in the Bunsen burner. (See p. 23.) 

 After sufficient blood has been collected (Fig. 12), the straight empty 

 end is sealed with a flame and then cooled (Fig. 14) . The blood is then 

 shaken into this sealed end, and the bent end, in turn, sealed with 

 the flame. Care should be 



taken not to .heat the 

 blood. When the serum 

 has separated, the tube is 

 opened by filing at a point 

 above the clot and breaking, 

 protecting the hands with 

 a towel. The serum is 

 carefully removed with a 

 capillary pipet and nipple 

 (Fig. 13). 



6. To obtain blood from 

 infants and small children 

 the large toe may be punc- 

 tured, but as a rule better 

 results are obtained by wet- 

 cupping or by puncturing a 



FIG. 12. COLLECTING BLOOD IN A WRIGHT 

 CAPSULE. 



vein. 



OBTAINING LARGE AMOUNTS OF HUMAN BLOOD 

 Larger quantities of human blood may be required for making com- 

 plement fixation reactions, the Abderhalden ferment test, etc. 



(a) Phlebotomy. 1. In adults, a prominent vein at the elbow, such 

 as the median basilic, is usually chosen. In children less than a year 

 old this vein is not suitable, better results being obtained when the ex- 

 ternal jugular or a temporal vein is used. 



2. Place a rubber tourniquet or a few firm turns of a wide muslin 

 bandage above the elbow. 



3. Apply tincture of iodin to the skin over the vein. The vein may 

 be rendered more prominent by directing the patient to open and close 

 the hand several times. 



3 



