INOCULATION OF CULTURE MEDIA 



17 



of the tube slightly downwards (so that no dust shall drop into 

 it) and to the right. Tubes of solid media should always be held 

 in this position during inoculation ; tubes of liquid media are held 

 in a similar way, but of course their mouths must point upwards. 



2. Put the projecting portion of the cotton-wool plug of the test- 

 tube into the flame so as to singe it ; this is to destroy any germs 

 which may have been deposited upon it from the atmosphere. 



3. Sterilize the points of the forceps by passing them slowly 

 through the flame, and then use them to remove the plug. Place 

 this between the ring and little fingers of the left hand, and put 

 the forceps down. 



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 



Fig. 9. 



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. 



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 



