DIPHTHERIA 189 



treated as such, whether the bacteriological examination 

 enables us to detect the bacillus or not. On the other hand, 

 bacteriological diagnosis will often insure the recognition of 

 a case of true diphtheria, in which the clinical symptoms 

 are ill defined, and which might, though slight in itself, give 

 rise to severe cases. After an attack the bacillus frequently 

 persists in the throat for considerable periods of time, 

 even amounting to seven and eight weeks after complete 

 apparent recovery from the disease. 



Method of Staining. — The diphtheria bacillus is readily 

 stained with the usual aqueous basic aniline dyes. Loffler's 

 methylene blue is the best general staining reagent for 

 cover-glass preparations. It is also stained by Gram's 

 method. 



Bacteriological Diagnosis of Diphtheria. — A suitable ' out- 

 fit ' for this purpose consists of a small box containing two 

 stoutglass test-tubes, both cotton-wool-plugged and sterilised ; 

 the one holds a cotton- covered iron wire, the other contains 

 Loffler's medium, duly sloped. 



With one end of the cotton swab, the suspected portion of 

 the throat is rubbed and the infection transferred to the 

 surface of the medium, taking care to rub lightly, so as not 

 to abrade the surface. 



The tube is now plugged, and either posted to a laboratory 

 or placed in the incubator, or it may be incubated on the 

 person by placing in the waistcoat pocket and buttoning 

 the coat over it. Better results are obtained by using an 

 ordinary platinum wire to inoculate the tube with, instead 

 of the cotton-covered swab, and when a platinum wire is 

 used, three streaks should be made on the medium, after 

 touching the throat once only. By this means a part of 

 one of these three streaks will probably be a pure culture of 

 the Klebs-Loffler, if it be present. 



After twelve hours' incubating, the tube is examined, and 



