TETANUS. 235 



injury, the site of inoculation may escape observation at 

 autopsy. If a mixed culture was inoculated e. g., tetanus- 

 infected earth, or pus or fragments of tissue from a wound 

 in a case of tetanus a focus of suppuration will be found 

 at the site of inoculation. No changes are demonstrable in 

 the remaining organs of animals dead of tetanus ; above all, 

 tetanus-bacilli have never been found present, and, likewise, 

 not in the blood. The bacilli have been demonstrated only 

 at the site of inoculation, and in rare instances in the 

 nearest adjacent lymph-glands ; but even in these places 

 they are present only in small number, and they usually 

 can be found only with great difficulty. 



The Nature of Tetanus. The postmortem findings just 

 described are explained by the fact that tetanus is an ex- 

 quisitely toxic-infectious disease. The convulsions and 

 death are due to a poison generated by the tetanus-bacilli 

 and rapidly absorbed from the site of inoculation. The 

 evidence in favor of this view has been derived from vari- 

 ous sources. In the first place, exactly the same clinical 

 picture can be developed with the germ-free filtrate of a 

 tetanus bouillon-culture, which thus contains only the dis- 

 solved chemic tetanus-toxin, as by means of the bacilli 

 themselves. In the next place, Kitasato has inoculated 

 mice with tetanus-bacilli at the root of the tail, and has 

 excised and cauterized the site of inoculation throughout 

 a large extent after one-half, one, and one and a half hours, 

 and longer, so that there was no chance for the bacilli, 

 which do not penetrate beyond the site of inoculation, to 

 be retained within the body, and only the toxin absorbed 

 could in any way be responsible for the further develop- 

 ment of the disease. Only those animals operated on half 

 an hour after inoculation remained well, while all of the 

 others were attacked with tetanus. This means that as 

 early as an hour after the inoculation so much toxin was 

 absorbed that the bacilli were no longer necessary to the 

 development of the attack of tetanus. 



The subordinate position taken by the bacilli in their sig- 

 nificance for the clinical picture, as compared with the 

 toxins to which they give rise, led Vaillard and Vincent to 

 the conclusion that the bacilli, through themselves and their 

 spores, are not alone capable of causing the disease, and that 

 in a pure state they are entirely inactive ; and only the layer 

 of toxin which adheres to them externally gives rise to the 



