400 BACTERIOLOGY. 



1 :1000, and in thirty minutes by the same solution plus 

 0.5 per cent, hydrochloric acid. 



Action upon animals. After subcutaneous inoculation 

 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 inoculation for rats and 

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

 bits 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^ of the tetanus bacillus 

 there is little to be seen by either macroscopic or micro- 

 scopic examination, and cultures from the seat of inocu- 

 lation are usually negative, in so far as finding the 

 tetanus bacillus is concerned. At the seat of inoculation 

 there is usually only a hypersemic condition. In uncom- 

 plicated cases there is no suppuration. The internal or- 

 gans do not present any change, and culture methods of 

 examination show them to be free from bacteria. The 

 death of the animal results from the absorption of a solu- 

 ble poison, either produced by the bacteria at the seat of 

 inoculation or, which seems more probable, produced by 



1 Animals and human beings that have become infected with this organism 

 in the natural way commonly present a condition of suppuration 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. 



