790 MICROBIOLOGY OF DISEASES OJ" MAN AND DOMESTIC ANIMALS 



from general loss of strength or involvement of the respiratory muscles. 

 The shorter the incubation period the higher the mortality. Few 

 recover when the incubation period is less than ten days, about half the 

 cases recover when the period is more than fifteen days. 



The nerves may show injury as indicated by swelling and redness 

 and microscopically nerve cells have been observed in a state of granu- 

 lar degeneration; there is a more or less distinct general congestion of 

 the organs. ' 



While lockjaw has been known clinically for centuries, it was not 

 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 occasionally by examination of 

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

 be obtainedby 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 

 aU vegetative forms and subsequently making subcultures. If other 

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

 countered. Subcutaneous inoculations of ihice 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. 



The B. telani is about 2/i to $ti in length by 0.311 to 0.8/i in width with rounded 

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

 "drum stick" appearance (Fig. 166). The arrangement is usually single, but 

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

 spores which have a diameter of in to 1.5^1. The young bacilli are motile and possess 

 SO 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- 

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

 14° to 4S° 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 

 develop in an atmosphere of carbon dioxide. Media for the cultivation of the 

 bacillus should be slightly alkaline and should contain for best growth about 2 

 per cent of glucose or 1.5 per cent sodium formate. The addition of pieces of fresh 

 raw sterile tissue is valuable. On agar at 37° colonies appear in forty-eight hours 

 which show microscopically, a mass of tangled threads resembling colonies of B. 

 subliUs or Bact. anthracis. In broth a cloudiness is produced in twenty-four to 



