Pathogenesis 395 



most cases of tetanus are cases of mixed infection in which 

 the bacillus enters with aerobic bacteria, which aid its 

 growth by absorbing the oxygen in the neighborhood. The 

 amount of poison produced must be exceedingly small and 

 its power tremendous, else so few bacilli growing under 

 adverse conditions could not produce fatal toxemia. The 

 toxin is produced rapidly, for Kitasato found that if mice 

 were inoculated at the root of the tail, and the skin and 

 the subcutaneous tissues around the inoculation afterward 

 either excised or burned out, the treatment would not save 

 the animal unless the operation were performed within 

 an hour after the inoculation. 



Some incline to the view that the toxin is a ferment, 

 and the experiments of Nocard* might be adduced in 

 support of the theory. He says: "Take three sheep with 

 normal tails, and insert under the skin at the end of each 

 tail a splinter of wood covered with the dried spores of the 

 tetanus bacillus"; watch these animals carefully for the first 

 symptoms of tetanus, then amputate the tails of two of 

 them 20 cm. above the point of inoculation, . . . the 

 three animals succumb to the disease without showing any 

 sensible difference." 



The circulating blood of diseased animals is fatal to 

 susceptible animals because of the toxin which it contains; 

 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 

 * Quoted before the Academic de Medicine, Oct. 22, 1895. 



