THE CULTIVATION OF BACTERIA. 73 



between the second and third and the third and fourth fingers 

 of the left hand, respectively. The wire may now be passed 

 into the first tube, which we will suppose to hold some material 

 containing bacteria, and a httle of this material may be removed 

 on the tip of the wire from the first tube to the second. When 

 the needle is introduced into or removed from either tube it 

 should not touch the side of the tube at any point, and should 

 only come in contact with the region desired. After inoculation 

 of the second tube has been effected the wire is to be heated to a 

 red heat in the flame, the necks of the tubes are to be passed 

 through the flame, and the plugs are to be returned to their 



Fig. 19. — ^Manner of Holding Tubes. 



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

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

 to dry the material on it before burning 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 

 wire loop may be used in the same manner as the straight wire, 

 especially when a substance containing a small number of 

 bacteria is being handled. 



When a tube of gelatin is to be inoculated the wire is usually 

 introduced into the medium vertically, "stab-culture"; when 

 a medium with a slanted surface is employed, as agar, potato 



