60 METHODS OF CULTIVATION OF BACTERIA, 



the glass rod are also passed two or three times through 

 the Bunsen flame. It is held between the right fore 

 and middle fingers, with the needle projecting backwards, 

 i.e. away from the right palm. Remove plug from culture 

 with right forefinger and thumb, and continue to hold 

 it between the same fingers, by the part which projected 

 beyond the mouth of the tube. Now touch the culture 

 with the platinum needle, and, withdrawing it, replace 

 plug. In the same way remove plug from tube to be 

 inoculated, and plunge platinum wire down the centre 

 of the gelatine to within half an inch of the bottom. It 

 must on no account touch the glass above the medium. 

 The wire is then immediately sterilised. A variation in 

 detail of this method is to hold the plug of the tube next 

 the thumb between the fore and middle fingers, and the 

 plug of the other between the middle and ring fingers, 

 then to make the inoculation (Fig. 15). The sub-culture 

 is labelled, and in a bacteriological laboratory a label 

 should never be licked. If a tube contain a liquid 

 medium, it must be held in a sloping position between 

 the same fingers, as above. When a stroke culture is 

 made the same manipulations are gone through. Here the 

 platinum loop is used, and a little of the culture is smeared 

 in a line along the surface of the medium from below 

 upwards. In inoculating tubes, it is always well, on remov- 

 ing the plugs to make sure that no strands of cotton fibre 



are adhering to the inside 

 of the necks. As these 

 might be touched with 

 the charged needle and 

 the plug thus be con- 

 taminated, they must be 

 removed by heating the 

 inoculating needle red- 

 FIG. 1 6. Rack for platinum needles. hot and scorching them 



off with it. When the 



platinum wires are not in use they may be laid in a rack 

 made by bending up the ends of a piece of tin, as in 



