

Pathogenesis 461 



and the fact that the urine is also toxic to mice proves that 

 the toxin is excreted by the kidneys. 



The organisms usually enter the body through a wound 

 caused by some implement which has been in contact with 

 the soil, or enter abrasions from the soil directly. Doubt- 

 less 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 disease, especially in man, is of con- 

 siderable duration (three to nine days), and at times permits 

 the wound to heal before any symptoms of intoxication 

 occur, serves to explain the occurrence of some of the 

 reported cases in which no wound is said to have existed. 



There are two classes of infected wounds particularly prone 

 to be followed by tetanus namely, those into which soil 

 has been carried by the injuring implement and those of 

 considerable depth. The infecting organism reaches the 

 first class in large numbers, but finds itself under aerobic 

 and other inappropriate conditions of growth. It reaches 

 the second class in smaller numbers, but finds the conditions 

 of growth better because of the depth of the wound. 



The severity of the wound has nothing whatever to do 

 with the occurrence of tetanus, pin-pricks, nail punctures, 

 insect stings, vaccination, and a variety of other mild 

 injuries sometimes being followed by it. 



An interesting fact has been presented by Vaillard and 

 Rouget,* who found that if the tetanus spores were intro- 

 duced into the body freed from their poison, they were 

 unable to produce the disease because of the promptness 

 with which the phagocytes took them up. If, however, 

 the toxin was not removed, or if the body-cells were injured 

 by the simultaneous introduction of lactic acid or other 

 chemic agent, the spores would immediately develop into 

 bacilli, begin to manufacture toxin, and produce the disease. 

 This suggests that many wounds may be infected by the 

 tetanus bacillus though the surrounding conditions rarely 

 enable it to develop satisfactorily and produce enough 

 toxin to cause disease. 



In very rare cases tetanus may possibly occur without 

 the previous existence of a wound, as in the case reported 

 by Kamen, who found the intestine of a person dead of 

 the disease rich in Bacillus tetani. Kamen is of the opinion 



* See "Centralbl. f. Bakt., Ihfekt., u. Parasitenk.," vol. xvi, p. 208. 



