24 ‘ BACTERIOLOGICAL DIAGNOSIS. 
hand, pointing the mouth of the tube slightly down- 
wards (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. Sterilise 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 
three or four inches of the glass rod slowly through the 
flame. Remember that every portion of the needle 
which goes inside the tube must be sterilised in the 
flame. 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 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. Sterilise 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. 
