38 CLINICAL BACTERIOLOGY AND 



Staining. — For original pus use Welsh's method. After 

 cultivation use carbol-methylene blue and Grain's method. 



Microscopical Appearances. — Cocci are arranged in fours. 



Aerobic. — Minimum temperature, 15° 0.; optimum, 35° C.j 

 maximum, 40° C. 



(b) Gram-Negative. — Micrococcus Catarrhalis* 



Biological Characters. — 1. On gelatin plates at room 

 temperature, 20° C, the growth is very rapid and the 

 colonies tough. 



2. On agar colonies very tough and opaque. 



Staining. — By Gram's counter-stain neutral red. 



Microscopical Characteristics. — The cocci are usually 

 arranged in pairs. 



Aerobic. — GroAving at room temperature freely. Minimum 

 temperature, 18° C. ; optimum, 37° C ; maximum, 40° C 



Differential Diagnosis of the More Common Patho- 

 genic Bacilli. 



A hanging-drop specimen should be made. 



A. Motile. — 1. B. tetani. 2. B. cedematus maligni. 

 3. B. pyoeyaneus. 4. B. coli communis. 5. B. anthracis 

 symptomatica. 6. B. bronchosepticus of Ferry. 



(a) Gram Positive. — Bacillus Tetani. 



Biological Characters. — 1. In broth anaerobically the 

 medium becomes clouded. 



2. In gelatin stab the growth radiates into the medium, 

 liquefies slowly, and forms gas. 



3. On agar growths form giving the colonies the appear- 

 ance of very fine wool. 



4. In agar stab the outgrowths give the appearance of a 

 fir-tree. 



* A microbe having close characteristics of the M. catarrhalis of 

 man has been isolated by the author from catarrhal discharges of horses 

 suffering from influenza. 



