THE USE OF THE ORDINARY CULTURE MEDIA 55 



expanded into a diamond shape, and its proximal is screwed 

 into an aluminium rod. It is very useful for making scrapings 

 from organs and for disintegrating felted bacterial cultures ; in 

 such manipulations the ordinary platinum wire is awkward to 

 work with, as it bends so easily. Cultures on a solid medium 

 are referred to (1) as "puncture" or "stab" cultures (German, 

 Stichkultur), or (2) as "stroke" or " slant " cultures (Strichkultur), 

 according as they are made (1) on tubes solidified in the upright 

 position, or (2) on sloped tubes. 



To inoculate, 1 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 j>erson holding them ; the plugs are twisted round 

 once or twice, to make sure they are not adhering 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 pro- 

 jecting backwards, i.e. away from the right palm. Remove plug 

 from culture 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 in- 

 oculated, 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 



FIG. 15. Another method of inoculating 

 solid tubes. 



