150 . BACTERIOLOGY 



of the proper temperature, a very small portion of the 

 mixture of organisms to be studied is taken up with a steril- 

 ized platinum wire (Fig. 23, a) about 5 cm. long, twisted 

 into a small loop at one end and fused into a bit of glass 

 rod, which serves as a handle, at the other extremity. This 

 loop is one of the most useful of bacteriological instruments, 

 as there is hardly a manipulation into which it does not 

 enter. Under no circumstances is it to be employed without 

 having been passed through a gas-flame until quite hot, 

 for the purpose of sterilization. One should form a habit 

 of never taking up one of these platinum-wire needles, as 



FIG. 23 

 a 



6 

 Looped and straight platinum wires in glass handles. 



they are called, for they are curved and straight (Fig. 23, 6) 

 as well as looped, without passing it through a flame; and 

 the sooner the beginner learns to do this as a reflex action, 

 the sooner does he eliminate one of the possible sources of 

 error in his work. It must be remembered, though, that it 

 should not be used when hot, otherwise the organisms taken 

 upon it will be killed by the high temperature; after steril- 

 ization in the flame one waits for a few seconds until it 

 is cool before using. 



A minute portion of the material under consideration is 

 transferred with the sterilized loop into tube No. 1, "the 

 original," where it is thoroughly disintegrated by gently 



