43° Diphtheria 



Distinct polar granules, Babes-Ernst granules, can be defined at the 

 ends of the baciUi by special methods of staining. Occasional 

 branched forms are observed, though Abbott and Gildersleeve* 

 do not regard branching as a phase of the normal development 

 of the organism and do not find it common upon the standard 

 culture media. The bacillus is peculiar in its pleomorphism, for 

 among the well-formed individuals which abound in fresh cultures a 

 large number of peculiar organisms are to be found, much larger 

 than normal, some with one end enlarged and club shaped, some 

 greatly elongated, with both ends similarly and irregularly expanded. 



Westbrook, Wilson and McDanielf have found it convenient 

 to describe three chief types of the diphtheria bacillus as it occurs 

 in twenty-four-hour-old cultures on LofHer's blood-serum, sent to 

 the laboratory for diagnosis. The classification places all types in 

 three general groups: (a) granular, (b) barred, and (c) solid or ' 

 evenly staining forms. Each group is subdivided into types based 

 on the shape and size of the bacilli. A study of variations in the 

 sequence of types in series of cultures derived from clinical cases of 

 diphtheria shows that (a) granular types are usually the most 

 predominant forms at the outset of the disease; (J) the granular types 

 usually give place wholly or in part to barred and solid types shortly 

 before the disappearance of diphtheria-hke organisms ; (c) sohd types, 

 by many obsevers called "pseudo-diphtheria bacilli," may cause 

 severe clinical diphtheria. Solid types may sometimes be re- 

 placed by granular types when convalescence is established and 

 just before the throat is cleared of diphtheria-like bacilli. 



Staining. — The bacillus can most readily and most character- 

 istically be stained with LofHer's alkaline methylene blue: 



Saturated alcoholic solution of methylene blue 30 



I : 10,000 aqueous solution of caustic potash 100 



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

 tion which keeps well is prepared by dissolving 2 grams of meth- 

 ylene blue and 5 grams of borax in 100 cc. of water. This is diluted 

 with from five to ten times its volume of water for ordinary use. 



The small dark-staining dots at the poles of the bacilli, the so- 

 called metachromatic or Babes-ErnstJ granules were at first thought 

 to be sporogenic granules. Later, when it became definitely known 

 that the organism produced no spores, their presence was thought 

 to be significant of virulence and special pains were taken to define 

 them by special methods of staining. An aqueous solution of dahlia 

 recommended by Roux for the purpose is made and used as follows: 

 Two solutions are prepared: 



* "Centralbl. f. Bakt.," etc., Dec. 18, 1903, Bd. xxxv, No. 3. • 

 t ''Trans. Assoc. Amer. Phys.," igoo; Trans. Amer. Public Health Assc, 

 1900; Jour. Boston Society of the Medical Sciences, 1900 iv, 75. 

 t "Zeitschrift fur Hygiene," 1889, v. 



