114 



APPLIED IMMUNOLOGY 



kno\vn positive and negative controls every day the 

 test is performed. 



Collection and Preparation of the Patient's Serum, 

 — The patient's blood to be tested may be drawn from 

 a vein at the bend of the elbow with a hypodermic 

 syringe and immediately transferred to a small test- 

 tube. There are several other methods in use, as by 

 means of Keidel's vacuum ampoule (Fig. 11), cup- 



FiG. 11. — Showing method of collecting blood from vein of arm with Keidel's 

 vacuum ampoule. Observe the tourniquet of rubber dam secured with the easily de- 

 tached, tucked-under loop. 



ping, etc. At least 2 c.c. of blood should be obtained. 

 The method employed by us is as follows : The ring- 

 finger is wiped off with alcohol, allowed to dry, and 

 then given a deep puncture at the radial extremity of 

 the distal phalanx about a quarter of an inch below 

 the angle of the nail with a large Hagedom needle. 

 The blood is then squeezed out into a small test-tube 

 by intermittently compressing the radial side of the 



