380 EXPERIMENTAL INFECTIONS DURING LIFE 



4. Puncture the vein with a sterile Hagedorn needle. 



5. Take a small blood-collecting pipette (Fig. 161) 

 and hold it at an angle to the ear, one end touching the 

 issuing drop of blood, the other depressed. 



The blood will now enter the pipette at first by 

 capillarity; afterward gravity will also come into 

 play and the pipette can be two-thirds filled without 

 difficulty. 



6. Hold the tube by the end containing the blood, 

 the clean end pointing obliquely upward warm this 



FIG. 192. Collecting blood from rabbit. 



end at the bunsen flame to expel some of the contained 

 air ; then seal the clean point in the flame. 



7. Place the pipette down on a cool surface (e. g., a 

 glass slide) . The rapid cooling of the air in the clean 

 end of the pipette creates a negative pressure, and the 

 blood is sucked back into the pipette, leaving the 

 soiled end free from blood. Seal this end in the bunsen 

 flame. 



8. Mark the distinctive title of the specimen (e. g., 

 animal's number) upon the pipette with a writing 

 diamond or grease pencil. 



9. When the sealed ends are cold and the blood has 

 clotted, place the pipette on the centrifuge, clean end 

 downward ; counterpoise and centrifugalise thoroughly. 

 On removing the pipette from the centrifuge, the red 

 cells will be collected in a firm mass at one end, and 

 above them will appear the clear serum. 



