336 APPLIED IMMUNOLOGY 



per cent, tincture of iodine, and a tourniquet of rubber dam 

 (R) is placed around the arm, sufficiently taut to render 

 the superficial veins about the elbow prominent, care being 

 exercised not to obliterate the radial pulse (Fig. 60). The 

 median cephalic or basilic vein is preferable to a vein exactly 

 in the cubital fossa, because, should inflammation in or 

 about the vein supervene, the patient will experience less 

 discomfort on flexion and extension of the elbow. The bu- 

 rette containing the required quantity of salvarsan solution 

 is given to an assistant to hold or it is suspended on a stand 

 adapted to the purpose (Fig. 60). At this point it is usually 

 possible to plunge the sharp pointed platino-iridium obliquely 

 through the skin into the vein, holding the needle with the 

 eye directed downward, at the same time fixing the skin in 

 the axis of the vein about two inches distant from the site 

 of puncture with the index finger or thumb of the hand not 

 holding the needle. As the needle is slowly and steadily ad- 

 vanced at an angle of about thirty degrees, always keeping it 

 at the plane of the axis of the vein, it will usually be possible to 

 see a slight dimpling of the skin overlying the vein at the 

 point where the needle will pierce the vein. Just as the sen- 

 sation, imparted to the fingers, of decreased resistance is 

 experienced, as the tip of the needle enters the lumen of the 

 vein, the skin dimple likewise disappears. Rarely, it will be 

 necessary in the case of young individuals, some women and 

 those exhibiting a thick layer of panniculus adiposis, when 

 the veins are extremely small or obscured by fat, to infiltrate 

 the skin with a few drops of a one per cent, novocain solution, 

 and then make a cutaneous incision one-half to three-quarters 

 of an inch in length, exposing the vein. The vein may or 

 may not be lifted from its sheath, but in any event it is then 

 possible to introduce the needle without difficulty, using 

 preferably the sharp-pointed one or occasionally the well- 



