BACILLUS TETANI 



459 



The most favorable temperature for the growth of this bacillus is 

 37.5° C. Slight alkalinity or neutrality of the culture media is most ad- 

 vantageous, though moderate acidity does not altogether inhibit growth. 

 All the media named may be rendered more favorable still by the ad- 

 dition of one or two per cent of glucose, maltose, or sodium formate.' 

 In media containing certain carbohydrates, tetanus bacilli produce acid. 

 In gelatin and agar, moderate amounts of gas are 

 produced, consisting chiefly of COj, but with the 

 admixtures of other volatile substances which give 

 rise to a characteristically unpleasant odor, not unlike 

 that of putrefying organic matter. This odor is due 

 largely to H2 S and methylmercaptan. 



The vegetative forms of the tetanus bacillus are 

 not more resistant against heat or chemical agents 

 than the vegetative forms of other microorganisms. 

 Tetanus spores, however, wiU resist dry heat at 

 80° C. for about one hour, Uve steam for about 

 five minutes; five per cent carbolic acid kiUs them 

 in twelve to fifteen hours; one per cent of bichlo- 

 rid of mercury in two or three hours. Direct 

 sunlight diminishes their virulence and eventually 

 destroys them.^ Protected from sunlight and other 

 deleterious influences, tetanus spores may remain 

 viable and virulent for many years. Henrijean * 

 has reported her success in producing tetanus with 

 bacilli from a splinter of wood infected eleven 

 years before. 



Pathogenicity. — The comparative infrequency of 

 tetanus infection is in marked contrast to the wide 

 distribution of the bacilli in nature. Introduced into 

 the animal body as spores, and free from toxin, they 

 may often fail to incite disease, easily falling prey to 

 phagocytosis and other protective agencies before the vegetative forms 

 develop and toxin is formed. The protective importance of phagocyto- 

 sis was demonstrated by Vaillard and Rouget,* who introduced tetanus 

 spores inclosed in paper sacs into the animal body. By the paper cap- 



> Kitasato, Zeit. f. Hyg., 1891. 



'v. Eisler und Pribram, in Levaditi, "Handbuch," etc., Jena, 1907. 



^Henrijean, Ann. de la soc. m6d. chir. de Liege, 1891. 



• Vaillard et Rouget, Ann. de I'inst. Pasteur, 1892. 



Fig. 98.— Older 

 Tetanus Cui/ture 

 IN Glucose Agar. 



