50 METHODS OF CULTIVATION OF BACTERIA 



To inoculate, say, one ordinary upright gelatin tube from 

 another, the two tubes are held in an inverted position between 

 the forefinger and thumb of the left hand with their mouths 

 towards the person holding them ; the plugs are twisted round 



once or twice, to make 

 sure they are not adher- 

 ing to the glass. The 

 short, straight platinum 

 wire is then heated to 

 redness from point to 

 insertion, and 2 to 3 

 inches of 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 

 Fm. 15. Another method of inoculating backwards, i.e. away 

 solid tubes. from the right palm. 



Remove plug from cul- 

 ture tube 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 

 gelatin 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). If a tube 

 contain a liquid medium, it must be held in a sloping position 

 between the same fingers, as above. For a stroke culture 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 removing the plugs, to 



FIG. 16. Rack for platinum needles. 



