THE TETANUS BACILLUS 505 



with any differences in the nature of the toxin, and an 

 antitoxin prepared with the toxin of one type is equally 

 protective against the toxins of other types. 



Pathogenic action. A young broth culture three or 

 four days old produces death in mice, guinea-pigs and 

 rabbits with the characteristic symptoms of tetanic 

 intoxication. This condition is due to the absorption of 

 toxin, and the bacilli do not invade the tissues. Bacilli 



FIG. 49. Guinea-pig inoculated with a small dose of tetanus toxin, 

 showing paralytic condition of right hind leg due to spasm. 



and spores deprived of their toxin by washing and heating 

 are not pathogenic. The tetanic intoxication in these 

 animals takes the form of tonic muscular spasm and not 

 of clonic spasms as in the natural disease in man (Fig. 49). 

 Thus, a guinea-pig receiving a dose of culture or toxin 

 into the muscles along the spine suffers from a tonic con- 

 traction of these muscles ; with a small dose of toxin the 

 muscles at and near the site of inoculation are most 

 affected. This local tetanus is sometimes met with in 



