502 PATHOGENIC MICROORGANISMS 



esses of children, Pfeiffer 43 found small, non-motile, Gram-negative 

 bacilli, which he was forced to separate from true influenza bacilli 

 because of their slightly greater size, and their tendency to form 

 threads and involution forms. These microorganisms are strictly 

 aerobic and grow, like true influenza bacilli, only upon blood media. 

 They are differentiated entirely by their morphology upon twenty- 

 four-hour-old blood-agar cultures. Wollstein/ 44 who has made a 

 careful study of influenza-like bacilli, both culturally and by agglu- 

 tination tests, has come to the conclusion that these bacilli are so 

 similar to the true influenza organisms that the term pseudo-influenza 

 should be discarded. Strains of similar bacilli isolated from cases of 



FIG. 52. KOCH-WEEKS BACILLUS. 



pertussis, while differing from the others in some of their character- 

 istics, could not properly be maintained as distinct species. 



KOCH-WEEKS BACILLUS. Koch, 45 in 1883, Weeks 46 and Kartulis, 

 in 1887, described a small Gram-negative bacillus found in connec- 

 tion with a form of acute conjunctivitis which occurs epidemically. 

 The bacillus is morphologically similar to B. influenzae, but is 

 generally longer than this and more slender. The bacilli grow only 

 at incubator temperature. Kecent studies by Anna Williams at the 



43 Pfeiffer, Zeit. f. Hyg., xiii, 1892. 



14 Wollstein, Jour. Exp. Med., viii, 1906. 



45 Koch, Arb. a. d. kais. Gesundheitsamt, iii ; Cent. f. Bakt., 1, 1887. 



46 Weeks, N. Y. Eye and Ear Infirmary Kep., 1895; Arch. f. Augenheilk., 1887. 



