28o 



MANUAL OF BACTERIOLOGY. 



serum mixture; the other contains a steel rod, around the 

 lower end of which a pledget_ of absorbent cotton has been 



wound and the tube afterwards 

 sterilized. The swab is wiped 

 over the suspected region in the 

 throat, taking care that it touches 

 nothing else, and is then rubbed 

 over the surface of the blood- 

 serum mixture. The swab is re- 

 turned to its test-tube and the 

 cotton plugs are returned to their 

 respective tubes. The plugs, of 

 course, are held in the fingers 

 during the operation, and care 

 must be taken that the portion of 

 the plug that goes into the tube 

 touches neither the finger nor any 

 other object. The principles, in 

 fact, are the same as those laid 

 down in general for the inocu- 

 lation of culture-tubes with bac- 

 teria (see page 72). Inboard of 

 health work these tubes are re- 

 turned to the office. When it is 

 desirable, a second tube may be 

 inoculated from the swab. The 

 tubes are placed in the incuba- 

 tor, where they remain for from 

 twelve to twenty-four hours, 

 and a microscopic examina- 

 tion is then made of smear pre- 

 parations stained with Loffler's methylene-blue. On LofHer's 

 blood-serum kept in the incubator the bacillus of diphtheria 

 grows more rapidly than the other organisms which are ordi- 



Fig. 84. — Bacillus of Diphthe- 

 ria, Culture on Glvceein- 



AGAE. 



