OBTAINING LARGE AMOUNTS OF ANIMAL BLOOD 



45 



at the distal end, and the artery divided between them. The proximal 

 end is then held with forceps within the mouth of a sterile cylinder or 

 large centrifuge tube. The wall of the artery is incised with fine scissors 

 proximal to the forceps, and the blood is allowed to flow into the ves- 

 sel. The yield of blood may be increased somewhat by exerting pres- 

 sure on the animal's abdomen and thorax. 



To avoid the risk of contamination in the foregoing method, the 

 apparatus shown in Fig. 21 may be used. The whole apparatus is 





FIG. 22. METHOD OF BLEEDING A RABBIT FROM THE CAROTID ARTERY, 

 THIRD METHOD. 



sterilized in the autoclav before using. After the artery has been ex- 

 posed and isolated, a temporary clamp is applied to the proximal end. 

 A small incision is made in the wall of the artery, and the cannula in- 

 serted and fastened with a ligature. The clamp is then removed, and 

 blood collected in a large tube. 



Third Method. The following method, employed at the Pasteur 

 Institute at Paris, has been found very useful. The animal a rabbit 

 or a guinea-pig is anesthetized, and secured to an operating-table. 

 The carotid artery is carefully and aseptically exposed, and separated 



