Staining 473 



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,f but disputed by Denny. { 

 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 



Emery prefers Hanson's borax methylene-blue. A stock 

 solution which keeps well is prepared by dissolving 2 grams 

 of methylene-blue and 5 grams of borax in 100 c.c. of water. 

 This is diluted with from five to ten times its volume of 

 water for ordinary use. An aqueous solution of dahlia 

 is 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 



The true diphtheria bacilli appear brown, with a dark blue 

 body at one or both ends; the pseudo-diphtheria bacilli 

 usually exhibit no polar bodies. 



* "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. 



t American Public Health Association (New Orleans) meeting, 

 1902. 



