MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 843 



until 1884 that the infectious character was demonstrated when Carlo 

 and Rattone and Nicolaier were successful in animal inoculations. 

 Kitasato obtained pure cultures of the bacillus in 1889. 



The organisms may be detected rarely by examination of 

 stained preparations of the pus from the wound. Pure cultures may 

 be obtained by inoculating an alkaline dextrose broth with pus or tissue, 

 incubating under anaerobic conditions for about forty-eight hours until 

 sporulation, then exposing half an hour to a temperature of 80 to kill 

 all vegetative forms and subsequently making subcultures. If other 

 spore-bearing bacteria are present considerable difficulty may be en- 

 countered. Subcutaneous inoculations of mice or guinea-pigs is a good 

 method for demonstrating the presence of the organism, but pure 

 cultures should be combined with some aerobe (say B. coli) to secure 

 results. 



FIG. 177. Tetanus bacilli showing end spores. (After Kolle and Wassermann from 



Still.) 



The B. tetani is about 2/z to 5/i in length by 0.3^1 to o.8/n in width with rounded 

 ends. The vegetative rods are uniformly cylindrical but the terminal spores give a 

 "drum stick" appearance (Fig. 177). The arrangement is usually single, but 

 threads may occur especially in old cultures. The organism forms round terminal 

 spores which have a diameter of IM to 1.5/1*. The young bacilli are motile and possess 

 50 to 70 peritrichic flagella. Motility is lost with sporulation. The bacillus is 

 stained by the aniline dyes and is Gram-positive. The spores are readily dem- 

 onstrated by the special stains. The range of temperature for growth is from about 

 14 to 45 with an optimum about 37. The organism is usually considered an 

 obligate anaerobe though experimentally aerobic strains have been developed but 

 with loss of pathogenic and toxogenic properties. Pure cultures do not 



