BACILLUS TETANI. 539 



sublimate, 1 : 1000, and in thirty minutes by the same 

 solution plus 0.5 per cent, of hydrochloric acid. 



ACTION UPON ANIMALS. After subcutaneous inocu- 

 lation of mice with minute portions of a pure culture 

 of this organism tetanus develops in twenty-four hours 

 and ends fatally in from two to three days. Rats, 

 guinea-pigs, and rabbits are similarly affected, but only 

 by larger doses than are required for mice, the fatal 

 dose for a rabbit being from 0.3 to 0.5 c.c. of a well- 

 developed bouillon culture. The period of incubation 

 for rats and guinea-pigs is twenty-four to thirty hours, 

 and for rabbits from two to three days. Pigeons are 

 but slightly, if at all, susceptible. 



The tetanic convulsions always appear first in the 

 parts nearest the seat of inoculation, and subsequently 

 become general. 



At autopsies upon animals that have succumbed to 

 inoculations with pure cultures 1 of bacillus tetani there 

 is little to be seen by either macroscopic or micro- 

 scopic examination, and cultures from the site of inocu- 

 lation are often negative in so far as finding the tetanus 

 bacillus is concerned. At the site of inoculation there is 

 usually only a hypersemic condition. In uncomplicated 

 cases there is no suppuration. The internal organs do not 

 present any macroscopic change, and culture-methods 

 of examination show them to be free from bacteria. 

 The death of the animal results from the absorption of 

 a soluble poison, either produced by the bacteria at the 

 site of inoculation or, which seems more probable, pro- 



1 Animals and human beings that have become infected with this 

 organism in the ordinary way commonly present a condition of sup- 

 puration at the site of infection ; this is probably not due, however, to 

 the tetanus bacillus, but to other bacteria that have also gained access 

 to the wound at the time of infection. 



