238 MANUAL OF BACTERIOLOGY. 



placental blood was added. She describes the organisms as 

 short, plump ovoid cells. Gram, negative. Colonies on agar 

 transparent, dew-drop-like, surrounded each by a hemolytic 

 zone. 



Bacillus Diphtheriae (Klebs-LofHer).— A straight or slightly 

 curved bacillus, usually 1.2 to 2.5 /. in length, with rounded or 

 slightly pointed ends, remarkable for showing irregularities 

 of form, sometimes being club-shaped or spindle-shaped; 

 branching forms have been found.* It is not motile and does 

 not form spores. 



There are two principal forms: One short and relatively 

 plump which takes a very intense uniform stain; the other, that 

 presented in the accompanying photograph. Fig. 81, shows the 

 irregularities mentioned. This irregular form shows sharply 

 marked, intensely stained portions alternating with clear un- 

 stained bands running across. This alternation of stained and 

 unstained areas is often quite symmetrical in the rods, giving 

 them the appearance of being striped at almost regular inter- 

 vals. At other times the stained portion is at one or both of 

 the swollen, club-shaped ends. With methylene-blue the 

 stained portions often appear distinctly red. Considerable 

 practice is necessary to acquire the familiarity required to make 

 diphtheria diagnoses. 



It is best stained with watery solutions of the aniline dyes, 

 especially LofHer's alkaline methylene-blue. Very character- 

 istic pictures are obtained by the method of Neisser: 



*Hill. Journal Medical Research. Vol. VII. 1902. 



