312 PUBLIC HEALTH BACTERIOLOGY 



well as aerobic spore-bearers which had developed into the 

 vegetative form. Agar plates were then inoculated from 

 the slants and incubated in a hydrogen atmosphere, and 

 on these tetanus bacilli grew. Rosenbach had previously 

 pointfd out the terminal spore formation of B. tetani, 

 and Nicolaier had described the bacillus, but could not 

 grow it in pure culture. 



Description. A slender bacillus, 2 to 5 micra long x 

 0-3 to 0-8 micron thick, with somewhat rounded ends. In 

 young cultures it is slightly motile, and by special staining 

 numerous peritrichal flagella are seen. In 24 to 48 hours 

 the bacilli develop spores which are at full size three to 

 four times the thickness of the bacillus in diameter, and 

 are formed at one end of the bacillus. The bacillus and 

 spore thus give the characteristic drumstick appearance. 

 It is easily stained with the usual dyes, and is positive to 

 Gram's method. Detached flagella often become massed 

 together in the form of spirals, not unlike spirochaetes. In 

 specimens stained with watery solutions of gentian-violet 

 or methylene - blue, the bacillary protoplasm stains 

 uniformly, but any spores are unstained except at the 

 periphery, and so look like rings. With carbol-fuchsin and 

 time, the spores become uniformly coloured. Spores 

 may be found free from the bacilli in which they were 

 formed. The bacillus liquefies gelatin slowly, also blood 

 serum, but does not coagulate milk. It is a strict anaerobe 

 (obligatory), but can be habituated to aerobic life, though 

 with loss of pathogenicity and toxin-forming power. Grows 

 moderately in aerobic conditions where other organisms 

 which use up the oxygen supply are present (symbiosis). 

 Its growth is aided in all media by slight alkalinity, 

 presence of glucose, maltose, or sodium formate (1 to 2 per 

 cent), which act as reducing agents. With carbohydrates 

 it produces acid. In gelatin and agar, moderate amounts 

 of gas are produced, chiefly CO 2 ; but other substances 

 which are volatile and cause a characteristically unpleasant 

 odour are formed. This is described as a peculiar burnt 

 odour, and as that of putrefying organic matter, and is 

 said to be largely due to H 2 S and CH 3 .SH (methyl 

 mercaptan). 



Cultures. In deep glucose gelatin stab : growth begins 



