CITRATED BLOOD AGAR 171 



Citrated Blood Agar. Guy's. 



1. Kill a small rabbit with chloroform vapour, and 

 nail it out on a board (as for a necropsy) ; moisten the 

 hair thoroughly with 2 per cent, solution of lysol. 



2. Sterilise several pairs of forceps, scissors, etc. by 

 boiling. 



3. Reflect the skin over the thorax with sterile 

 instruments. 



4. Open the thoracic cavity by the aid of a fresh 

 set of sterile instruments. 



5. Open the pericardium with another set of sterile 

 instruments. 



6. Sear the surface of the left ventricle with a red- 

 hot iron. 



7. Take a steiile capillary pipette (Fig. 13,^); break 

 off the sealed extremity with a pair of sterile forceps. 



8. Steady the heart in a pair of forceps and thrust 

 the point of the pipette through the wall of the ven- 

 tricle and through the seared area, apply suction to 

 the plugged end of the pipette and fill it with blood. 



9. Transfer the entire quantity of blood collected 

 from the rabbit's heart to a small Erlenmeyer flask 

 containing a number of sterile glass beads and 5 c.c. 

 concentrated sod. citrate solution. (See page 378.) 



10. Agitate thoroughly and set aside for a couple of 

 hours. 



1 1 . Melt up several tubes of nutrient agar (see page 

 167) and cool to 42 C. 



12. With a sterile 10 c.c. graduated pipette transfer 

 i c.c. citrated blood from the Erlenmeyer flask to each 

 tube of liquefied agar. Rotate the tube between the 

 hands in order to diffuse the citrated blood evenly 

 throughout the agar. 



13 . Place the tubes in a sloping position and allow the 

 medium to set. 



14. Place tubes of blood agar for forty-eight hours in 



