240 CLINICAL BACTERIOLOGY. 



convulsions occur. If the infection is single that is, if 

 pyogenic cocci do not gain entrance into the wound at the 

 same time as the tetanus-bacilli there will be no focus of 

 suppuration at autopsy to indicate the portal of infection. 

 In an animal experiment recorded by Vaillard spores healed 

 without reaction in the wound induced artificially, and 

 only some time later, when the affected member was 

 irritated, did tetanus occur. The cases of tetanus that occur 

 in connection with wounds treated antiseptically are suscep- 

 tible of a similar interpretation. The tetanus-bacillus may 

 long remain latent ; the antiseptic employed not being power- 

 ful enough to destroy the tetanus-spores with which the 

 wound is infected, and these are included in the healing 

 wound, to proliferate and to induce the disease later in con- 

 sequence of some predisposing influence. The period of 

 incubation of tetanus in human beings varies from one to 

 twenty-two days ; in the case of an injury induced in the 

 laboratory with tetanus-toxin it was four days. The course 

 of the disease is the more violent, and the prognosis the 

 more unfavorable, the shorter the period of time that, has 

 intervened between the infliction of the injury (infection) 

 and the outbreak of the disease. Recovery took place in 

 only slightly more than three per cent, of cases with an in- 

 cubation-period of from one to ten days ; in twenty-five per 

 cent, of those with an incubation-period of from ten to 

 twenty-two days ; and in as high as fifty per cent, of those 

 with longer periods of incubation. The susceptibility of 

 human beings to the toxin of tetanus must, therefore, be 

 looked upon as pronounced. 



Bacteriologic Diagnosis. If it is desired to demonstrate 

 the bacilli in the pus, or in the granulation-tissue of the 

 wound in a case of tetanus, or if a specimen of earth or a 

 splintef of wood is to be examined for the presence of 

 tetanus-bacilli in order to discover the source of infection, 

 the suspected material may be directly introduced into a 

 pocket of skin at the root of the tail of a mouse. If the 

 animal dies of tetanus in the course of a few days, the 

 pus at the site of inoculation is treated in the manner 

 described for the purpose of obtaining a pure culture (p. 

 232). The material to be examined may also be intro- 

 duced into bouillon, through which a current of hydrogen 

 is passed, and which is then placed in the thermostat for 

 from three to five days. The mixed culture that has 



