TETANUS. 279 



contact with the soil, or enter abrasions from the soil 

 directly. Doubtless many of the wounds are so small 

 that their existence is overlooked, and this, together 

 with the fact that the period of incubation of the dis- 

 ease, especially in man, is of considerable duration, and 

 at times permits the wound to heal before any symptoms 

 of intoxication occur, serves to explain to us at least some 

 of the reported cases in which no wound is said to have 

 existed. 



It would seem that in some rare cases tetanus can occur 

 without the previous existence of a wound. Such a case 

 has been reported by Kamen, who found that the intes- 

 tine of a person dead of the disease was rich in the 

 Bacillus tetani. Kamen is of the opinion that the 

 bacilli can grow in the intestine and be absorbed, espe- 

 cially where there are imperfections in the mucosa. It 

 is not impossible, though he does not think it probable, 

 that the bacteria growing in the intestine could elaborate 

 enough toxin to produce the disease by absorption. 



All animals are not alike susceptible to the disease. 

 Men, horses, mice, rabbits, and guinea-pigs are all sus- 

 ceptible ; dogs are much less so. Most birds are scarcely 

 at all susceptible either to the bacilli or to the poison. 

 Amphibians are immune, though it is said that frogs 

 can be made susceptible by elevation of their body- 

 temperature. 



When a white mouse is inoculated with an almost 

 infinitesimal amount of bouillon or solid culture, or is 

 inoculated with garden-earth containing the tetanus 

 bacillus, the disease is almost certain to follow, the 

 first symptoms coming on in from one to two days. 

 The mouse develops typical tetanic convulsions, which 

 begin first in the neighborhood of the inoculation, but 

 soon become general. Death follows sometimes in a 

 very few hours. In rabbits the period of incubation is 

 nearly two weeks, and in man may be three weeks. 



The conditions in the animal body are not favorable 

 for the development of the bacilli, because of the free 



