DRAWING OF BLOOD. 461 



bottom of this and of a small test-tube should be heated in the blast- 

 lamp and then' fused together. A narrow or medium flame should 

 then be directed against the large test-tube at about 2 or 3 cm. from 

 the end. On slow rotation and careful heating a thickened constric- 

 tion results. The two portions are then drawn apart and the capil- 

 lary sealed as above. 



The carotid artery of the anesthetized animal is 

 exposed and a sterile silk thread is slipped under the 

 vessel. A pair of pression forceps are applied to the artery 

 as far up the neck as possible; or the artery may be tied 

 in this place. A second pair are then applied about 3 cm. 

 below this point. The distended artery is grasped with an 

 ordinary wide-tipped forceps, just below the upper clamp, 

 and slightly stretched. It is then nicked with a pair of very 

 fine scissors. After inserting the blades of a narrow-pointed 

 pair of forceps the vessel can be distended so as to readily 

 admit the introduction of the open end of a pipett^. The 

 end of the pipette, which should not be too narrow, is 

 broken off, and flamed to fuse the sharp edges; when cool 

 it is inserted as far as possible into the vessel. The liga- 

 ture is then tied over the glass tip; or this may be held 

 between the thumb and fore-finger. When the lower artery 

 forceps are opened, the blood rapidly fills the sterile pipette. 

 If necessary, suction can be applied to the end of the tube. 

 When enough blood has been drawn the artery is again 

 clamped, and the pipette is then removed and sealed in a 

 blast-lamp. The artery should then be tied above and 

 below the wound. After the blood-serum separates from 

 the clot, it can be transferred to sterile tubes by means of 

 a bulb pipette (Pig. 61 e). 



When only a small quantity of blood is desired it can be obtained 

 more easily from the jugular vein. Small bulb pipettes (Fig. 61 e) can 

 be employed in the manner indicated above. Moreover, a syringe 

 can be used to advantage in drawing blood from a vein. Several c.c. 

 of blood can thus be drawn in a few moments from the external 

 jugular or from the ear vein of a rabbit. 



