56 METHODS OF CULTIVATION OF BACTERIA 



(Fig. 13, b). The latter is referred to as the platinum "loop" 

 or platinum "eyelet," and is used for many purposes. "Taking 

 a loopful" is a phrase constantly used. The third wire 

 (Fig. 13, c) ought to be 4£ inches long and straight. It is used 

 for making anaerobic cultures. It is also very useful to have 

 at hand a platinum-iridium spud. This consists of a piece of 

 platmum-iridium about 1J inch long, 2 mm. broad, and of 

 sufficient thickness to give it a firm consistence ; its distal end is 

 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 



Fig. 13. — Platinum wires in glass handles. 



». Straight needle for ordinary puncture inoculations. 6. Platinum " loop." 



c. Long needle for. inoculating " deep" tubes. 



such manipulations the ordinary platinum wire is awkward to 

 work with, as it bends so easily. 



If a platinum wire heavily charged with bacteria be sterilised in a 

 Bunsen flame it may "spark" and unkilled bacteria may thus fall on 

 the worker's bench. In working with organisms highly pathogenic to 

 man, e.g., glanders, plague, Malta fever, it is well to substitute for plati- 

 num needles glass rods drawn out to capillary diameter, each of which can 

 be destroyed after use. These before use are sterilised by passing 

 through the flame, and when contaminated are dropped into a 1-1000 

 solution of corrosive sublimate instead of being heated. 



Cultures on a solid medium are referred to (1) as "puncture'' 

 or "stab" cultures, or (2) as "stroke" or "slant" cultures, 

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

 position, or (2) on sloped tubes. 



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 adhering to the glass. 

 The short, straight platinum wire is then heated to redness from 



