208 



BACTERIA 



Morphology and Stains. Long, bent, or curved bacilli of 

 irregular contour, frequently clubbed or filiform at one or both 

 ends ; which contain chroma tophilic granules, and often exhibit true 

 branching ; have no spores or flagella, and are not motile. Accord- 

 ing to Wesbrook, stained bacilli are of three types; (i) granular 

 (containing the Babes-Ernst granules); (2) barred like a striped 

 stocking; or (3) solid, staining uniformly throughout. The pleo- 

 morphic differences of various bacilli are most characteristic, and 

 of diagnostic importance. This organism stains with all the basic 



* B 



"^ 





t 





FIG. 62. Forms of B. diphtheria in cultures -on Loffler's serum. A, 

 Characteristic clubbed and irregular shapes with irregular staining of the 

 cell contents. X noo. B, Irregular shapes with even staining. X 1000. 

 (After Park and Williams.) 



dyes, notably by LofHer's blue, or Neisser's special granule stain. 

 It is also stained by Gram's method. The length of the organism 

 differs much, according to the reaction of the medium in which it 

 grows. Alkaline media favor long forms, and acid the reverse. 

 Its length is from i-5/i to 3.5^- It does not form chains. Bizarre, 

 or involution shapes predominate in old cultures (Fig. 63). 



Culture and Temperature Requirements. It grows best at 

 body temperature, and on glycerine agar, or in Loffler's blood 

 serum mixture of alkaline reaction. 



Vital Characteristics It resists drying for a long time, and has 



