420 Diphtheria 



the involution of the organism takes place with great 

 rapidity, so that large clubbed organisms and large or- 

 ganisms with polar granules are very common. On the 

 other hand, upon agar and glycerin agar-agar, where the 

 organism grows very slowly, it usually appears in the form 

 of short spindle and lancet shapes. So different are these 

 forms that a beginner would certainly fail to recognize them 

 as identical. The small short forms also stain much more 

 uniformly than the large club-shaped bacilli. 



Wesbrook * has established certain morphologic types of 

 the bacillus (see illustration), and from the appearances 

 presented draws conclusions regarding their virulence, 

 which are confirmed by Gorham,t but disputed by Denny. J 

 The rapidly growing bacilli with clubbed ends and polar 

 granules are supposed to be virulent forms; the slowly 

 growing, uniformly staining forms, non-virulent bacilli. 

 Park and Denny believe that the uniformly staining bacil- 

 lus, when it develops in blood- serum cultures, is the pseudo- 

 diphtheria bacillus, an entirely different organism. 



Staining. The bacillus can readily be stained with aque- 

 ous solutions of the anilin colors, but more beautifully and 

 characteristically with Loffler's alkaline methylene-blue : 



Saturated alcoholic solution of methylene-blue . . 30 

 1 : 10,000 aqueous solution of caustic potash . . 100 



or in an aqueous solution of dahlia, as recommended by 

 Roux. 



The Neisser method of staining the diphtheria bacillus, 

 which met with a very cordial reception, is as follows: 



The prepared cover-glass is immersed for from two to 

 three seconds in 



Alcohol (96 per cent.) 20 parts 



Methylene-blue 1 part 



Distilled water 950 parts 



Acetic acid (glacial) 50 



Then for three to five seconds in 



Bismarck brown 1 part 



Boiling distilled water 500 parts 



* "Trans. Assoc. Amer. Phys.," 1900, and "Trans, of the Amer. 

 Public Health Assoc.," 1900. 



t "Journal of Medical Research," N. S., vol. i, p. 201, 1901. 



J American. Public Health Association (New Orleans) meeting, 

 1902. 



