50 METHODS OF OBTAINING HUMAN AND ANIMAL BLOOD 



4. The wool on the left side of the neck is clipped closely with scis- 

 sors and alcohol applied. 



5. The operator then grasps the neck low down with the left hand, 

 and by means of the thumb exerts pressure over the base of the neck. 

 The external jugular vein will be found in a groove between the omo- 

 hyoid and sternomastoid muscles (Fig. 24). Firm pressure over the 

 base of the neck usually distends the vein, which may be seen or easily 

 felt. After locating the vein, the pressure should be released for an 

 instant, when the distention will disappear. In this way the operator 

 may be more certain that he has located the vein. 



6. A sterile stout needle, at least two inches in length and provided 

 with a trocar and special shank for firm grasping, is passed quickly into 

 the distended vein in an upward and inward direction (Fig. 25). It is 

 essential that the needle be sharp, otherwise it will be turned aside by 

 the wall of the vein. The end of the needle must not have too long a 

 bevel, or the point will pierce the opposite wall before the body of the 

 needle is well within the vein. The trocar is now removed, and blood 

 collected in a flask or bottle and defibrinated with glass beads and rods. 

 A short piece of rubber tubing may be attached to the needle. A suc- 

 tion apparatus is not needed because the flow of blood is good so long 

 as pressure is preserved over the vein at the base of the neck. 



7. When the required amount of blood has been secured, pressure is 

 released and the needle quickly withdrawn. Bleeding ceases at once, 

 and the neck is then washed with alcohol. 



8. By this method the same vein may be used over and over again 

 for several .years. I have never known infection to occur, although the 

 gradual formation of scar tissue about the site of puncture may inter- 

 fere with the operation. 



Hog. Blood may be secured from hogs by clipping off a small por- 

 tion of the tail with a sharp razor or scissors, beginning at the tip. 

 Bleeding is usually quite free, but is easily controlled by a tourniquet 

 and bandage. The serum of hogs immunized against hog cholera is 

 secured in this manner. 



Monkey. 1. Small quantities of blood up to 10 or 20 c.c. may 

 readily be obtained from a small vein just beneath the skin which 

 crosses over the inner malleolus at the ankle. When a tourniquet is 

 applied, the vein becomes prominent; the hair is clipped, and tincture 

 of iodin applied over the skin; a small needle is passed into the vein, 

 and the blood collected in a centrifuge tube. 



2. Large quantities of blood may be obtained from the femoral or 

 external jugular vein under light ether anesthesia. 



