Staining 647 



the name of acute conjunctivitis] is characterized by the 

 constant presence in the conjunctival secretions of a small 

 bacillus seen for the first time by Koch, but studied some 

 years later by Weeks, and now known as the bacillus of 

 Weeks." 



Further descriptive and clinical information can be found 

 in a paper by Weeks, ' ' The Status of our Knowledge of the 

 ^Stiological Factor in Acute Contagious Conjunctivitis."* 



Morphology. The organism is said to bear some resem- 

 blance to the bacillus of mouse-septicemia. It measures 

 i to 2 X 0.25 fi. (Weeks). The length is more constant in 



Fig. 193. Koch- Weeks' bacillus from conjunctival exudate at third 

 day of epidemic conjunctivitis (obj. Spencer one-twelfth oil-immersion) 

 (Boston). 



individuals found in the pus than those taken from cultures. 

 In cultures the organisms sometimes form long chains, the 

 division between the individuals being very indistinctly 

 marked. No spores are observed. The organism has no 

 flagella and is not motile. 



Staining. Weeks found that the organism stained well 

 with watery solutions of methylene-blue, basic fuchsin or 

 gentian violet. The color is fainter than that of the nuclei 

 of the associated pus corpuscles, and is much less intense in 

 old than in fresh cultures. It is readily given up when 



* "New York Eye and Ear Infirmary Reports," vol. m, Part I, 

 Jan., 1895, p. 24 



