THE TETANUS BACILLUS 



421 



killed by boiling for five minutes. Carbolic acid (1 : 20) 

 does not destroy the spores under about fifteen hours. 



Occurrence and pathogenic action. Man and the horse 

 are most subject to tetanus ; cattle and sheep are rarely 

 affected, while the fowl, frog, triton, snake and tortoise 

 are immune. Mice, guinea-pigs and 

 rabbits are all very susceptible. The 

 bacillus is present in the superficial 

 layers of the soils in many localities, but 

 not in all, and this accounts for the fact 

 that tetanus is rare in some places and 

 frequent in others. The natives of the 

 Solomon Islands have made use of this 

 fact for the preparation of poisoned 

 arrows. The arrows are tipped with a 

 viscid fluid, then rubbed in the soil from 

 a mangrove swamp containing tetanus 

 spores, and afterwards dried. Individuals 

 wounded with these arrows generally de- 

 velop tetanus. 



Tetanus spores are frequently present 

 in the dejecta of cattle, horses, and 



other animals, and occasionally of man 

 , . 90 v FIG. 47. Tetanus 



bacillus. Stab- 



The bacillus is confined to the seat culture in glucose 

 of inoculation, or at most is met with a f ar ' seven days 

 in the nearest lymphatic glands, so 

 that the general symptoms are due to the absorption of 

 toxin. The researches of Ransom and Meyer have shown 

 that the tetanus toxin is mainly absorbed by the nerve- 

 trunks (see also p. 159). The organisms associated with 

 the tetanus bacillus in earth are probably of considerable 

 importance in the production of the disease, for it has been 

 shown that if the tetanus bacilli and their spores be care- 

 fully washed so as to remove all adherent toxins, they fail 



