VACCINE-THERAPY 43 



B. Non- Motile: (a) Gram-Positive. — Bacilli of acne, 

 anthrax, tuberculosis, diphtheria, and actinomycosis.* 



Bacillus Acne Contagiosa Equi. 



Biological Characters. — 1. In gelatin stab white colonies 

 develop along the course of the needle. 



2. On agar white colonies growing very slowly. 



Staining. — Difficult to stain with ordinary dyes, but by 

 Gram's method. 



Microscopical Appearances. — Small ovoid bacilli, single, 

 and also forming chains. 



Anaerobic — at least, at first. Optimum temperature, 37° C. 



Bacillus Anthracis. 



Biological Characters. — 1. On gelatin plates small white 

 colonies appear, and if examined with an eyepiece, charac- 

 teristic threads projecting from the edges of the colonies 

 are noted. In gelatin stab after twenty-four hours a thick 

 white central column appears, from which radiate lateral 

 branches, giving the whole growth a triangular appearance, 

 with the apex at the bottom. 



Liquefaction begins at the top, extending downwards. 



2. On agar growth is similar to gelatin plates. 



Staining. — Original material ordinary aniline dyes, and 

 by Gram's method. 



Note McFadyean's violet colour reaction with methylene 

 blue. 



Microscopical Appearances. — The bacilli appear as large 

 rods, and often in threads. In stained specimens the ends 

 are square and the body slightly concave, giving it the 

 appearance, if in thread form, of a bamboo cane. 



Facultative Aerobic. — Minimum temperature, 10° C. ; 

 optimum, 35° C.j maximum, 45° C. 



* Actinomycosis is not a bacillus, but for convenience is described 

 here. 



