IB CLINICAL BACTERIOLOGY AND H^EMATOLOGY 



4. Take the platinum needle in the right hand, heat the whole' 

 of the wire to redness, and pass the lower 3 or 4 inches of the 

 glass rod slowly through the flame. Remember that every portion 

 of the needle which goes inside the tube must be sterilized in this 

 way. Allow the needle to cool ; you should have found out how 

 long this will take by a previous experiment. 



5. Dip the tip of the needle into the pus ; pass it into the tube 

 until it reaches nearly to the bottom of the tube (now uppermost), 

 and allow it to rest upon the sloping surface of the medium ; now 

 withdraw it gently, allowing the tip of the wire to trail gently 

 along the whole length of the sloped surface. Do not touch the 

 medium with the glass shoulder of the needle, and do not injure 

 the surface of the medium with the point of the wire. 



Fig. 9. 



6. Sterilize the needle as before. This step must never be 

 forgotten. 



7. Take the cotton-wool plug in the forceps, put it in the flame, 

 and singe all parts of its surface. Then plug the tube while the 

 wool is still burning. Label it. 



To make a stab culture take the other gelatin tube and proceed 

 as before until you get to step 5. When you have passed the 

 needle into the tube drive it steadily into the medium, taking care 

 not to deviate from the axis of the tube. Finish the process as 

 before. 



All this may seem involved. As a matter of fact it is very 

 simple, and need not take more than a minute to perform. But 

 every step must be carried out, and the whole process must be 

 learnt so thoroughly that it is performed automatically whenever 

 a culture is made. 



