THE BACILLUS OF TETANUS. ggl 



pigs, and rabbits are similarly aiFected, 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-develojied 

 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 ' of the tetanus bacillus 

 there is little to be seen Ijy either macroscopic, micro- 

 scopic, or culture examination. At the seat of inocu- 

 lation there is usually only a hypersemic condition. 

 There is no suppuration. The internal organs do not 

 present any change, and culture methods of examina- 

 tion 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 seat of 

 inoculation or, which seems more probable, produced 

 by the bacteria in the culture from which they are 

 obtained and introduced with them into the tissues of 

 the animal at the time of the inoculation. In support 

 of the latter hypothesis : Mice have been inoculated 

 with pure cultures of this organism ; after one hour 

 the point at which the inoculation was made was excised 

 and the tissues cauterized with the hot iron ; notwith- 

 standing the short time during which the organisms 



1 Animals and human loeings 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. 



17* 



