THE DIPHTHERIA BACILLUS 185 



of a tube of freshly prepared Loeffler's serum, a tube containing 

 a sterile swab of absorbent cotton firmly wound on a strong iron 

 wire, and printed directions and record form. The whole outfit 

 is inclosed in a metal or wooden box. 



In order to obtain a satisfactory culture the patient is placed 

 in a good light; the tongue is depressed and the swab, removed 

 from its tube, is gently but firmly rubbed against any visible mem- 

 brane without being allowed to touch any other part of the mouth 

 or throat. The swab is immediately inserted in the serum tube 

 and the portion which has touched the exudate rubbed on the 

 surface of the media; it is then returned to its tube, the plug 

 inserted, and both tubes with the record blanks filled out are 

 returned to the laboratory. 



When there is no visible membrane it is advisable to make two 

 cultures, one from the nose and another from the throat. Need- 

 less to say, cultures should not be made shortly after the applica- 

 tion of a disinfectant. 



On reaching the laboratory the inoculated tubes are placed 

 in an incubator at 37 C. for twelve hours ; at the end of that time 

 and often before the serum will be found to be dotted with small 

 colonies. A microscopic preparation is made by first placing a 

 platinum loopful of sterile water upon a glass slide, and then by 

 means of a platinum needle a number of typical colonies are 

 removed from the culture tube and smeared in the droplet of 

 water over the slide. The preparation is fixed in the usual way 

 and stained with Loeffler's methylene blue for about five minutes. 

 Examined with the oil immersion lens the film may show enormous 

 numbers of diphtheria bacilli with few cocci, or the reverse, or an 

 equal number of both forms. 



An immediate diagnosis can often be made without the use of 

 cultures by smearing a little of the exudate from the swab directly 

 over the slide. The result is a little less satisfactory ; the bacilli 

 appear less typical and are mixed with fibrin and epithelial cells. 



Animal Inoculations as a Test of Toxicity. No means of deter- 

 mining with certainty the virulence of diphtheria and diphtheria- 

 like organisms found in the throats of patients not showing signs 



