388 TETANUS. 



nus developing in dipiitheria patients who were being treated with antitoxin. 

 Evidence was brought forth which showed tha;t a horse supplying the antitoxic 

 serum had died of tetanus shortly after the bleeding which furnished the fatal 

 serum, but at the time of the bleeding no symptoms of tetanus had been notice- 

 able. Samples of this serum proved to contain enough tetanus toxin in o.i c.c. 

 to kill a guinea-pig in a few days. 



With these facts before them, Bolton and Fisch carried out a study upon 

 five horses, three of which were inoculated artificially with B. tetani, and two 

 in which tetanus had developed accidentally. Summarized, their results show 

 that : — 



1. Tetanus toxin may appear in the blood of infected horses four to five days 



before symptoms of tetanus are manifested, and sufl5cient to kill human 

 beings in doses of lo-ioo c.c. of such a serum. 



2. Within a day or two of the death of an infected horse, having some or no 



symptoms of tetanus, the toxin reaches a maximum and then rapidly de- 

 clines, so that shortly before death no toxin can be demonstrated. 



3. Shortly before death circulating toxin is replaced by antitoxin. 



4. It is quite a difficult matter to induce tetanus in the horse by artificially 



inoculating it with tetanus-bearing earth. 



In the light of the above results, which are decidedly impressive, it is now 

 imperative, for the preservation of the public, that all diphtheria antitoxic 

 serum shall be tested for tetanus toxin before being marketed, whether horses 

 furnishing the serum appeared to be in health or not. 



There is one question which must arise in connection with 

 tetanus, namely : Granted that the B. tetani is so widely present 

 in the soil, how is it that the disease is not more common than 

 it is, for wounds must constantly be contaminated with such 

 soil .' Experiments by Vaillard throw light on this point. We 

 have seen that unless suitable precautions are adopted, in exper- 

 imental tetanus in animals death results not from inoculation 

 but from an intoxication with toxin previously existent in the 

 fluid in which the bacilli have been growing. According to 

 Vaillard, if spores rendered toxin-free by being kept for a suf- 

 ficient time at 80° C. are injected into an animal, death does 

 not take place. It was found, however, that such spores can be 

 rendered pathogenic by injecting along with them such chemicals 

 as lactic acid, by injuring the point of inoculation so as to cause 

 effusion of blood, by fracturing an adjacent bone, by introduc- 

 ing a mechanical irritant such as soil or a splinter of wood (as 

 in Kitasato's experiments), or by the simultaneous injection of 

 other bacteria such as the staphylococcus pyogenes aureus. These 

 facts, especially the last, throw great light on the disease as it 

 occurs naturally, for tetanus results especially from wounds 



