THE CULTIVATION OF BACTERIA. 79 



palm, with the mouth pointing upward and to the right. 

 When two tubes are being used at the same time, as 

 is often necessary, they are placed side by side between the 

 thumb and forefinger of the left hand. The two plugs are held 

 between the second and third and the third and fourth fingers 

 of the left hand, respectively. Inoculation from one tube to the 

 other is effected by touching the tip of the platinum wire to the 

 material to be transferred in the one tube, and introducing it 

 into the culture-medium contained in the other tube. When 

 the needle is introduced into or removed from either tube it 

 should not touch the side of the tube at any point, but be 



Fig. 19. — Manner of holding tubes. 



brought in contact only with the medium to be inoculated. 

 After inoculation of the tube has been effected the wire must 

 be heated to a red heat in the flame, the mouths of the tubes 

 passed through the flame, and the plugs returned to their 

 respective tubes. When the wire to be sterilized is wet it 

 should be approached to the flame gradually, so as to dry the 

 material on it, in order to avoid "sputtering" (see page 22). 

 It is well from the start to train one's self to sterilize the platinum 

 wire every time it is taken from the table and before it is laid 

 down- again. The platinum loop is used in place of the 

 straight wire when it is desired to transfer larger amounts of 

 material than can be done at one time on a straight wire. 



