TOXINS OF THE TETANUS BACILLUS 379 



as we shall see, was sufficient to destroy the activity of the toxins. 

 When such splinters are introduced subcutaneously, death results 

 by the development of the spores which they carry. In this way 

 he completed the proof that the bacilli by themselves can form 

 toxins in the body and produce the disease. Further, if a small 

 quantity of garden earth be placed under the skin of a mouse, 

 death from tetanus takes place in a great many cases. [Some- 

 times, however, in such circumstances death occurs without 

 tetanic symptoms, and is not due to the tetanus bacillus but to 

 the bacillus of malignant oedema, which also is of common 

 occurrence in the soil (vide infra).] By such experiments, supple- 

 mented by the culture experiments mentioned, the natural 

 habitats of the b. tetani, as given above, have become known. 



The Toxins of the Tetanus Bacillus. The tetanus bacillus 

 being thus accepted as the cause of the disease, we have to 

 consider how it produces its pathogenic effects. 



Almost contemporaneously with the work on diphtheria was the 

 attempt made with regard to tetanus to explain the general symptoms 

 by supposing that the bacillus could excrete soluble poisons. The 

 earlier results in which certain bases, tetanin and tetanotoxin, were 

 said to have been isolated, have only a historic interest, as they were 

 obtained by faulty methods. In 1890 Brieger and Fraenkel announced 

 that they had isolated a toxalbumin from tetanus cultures, and this body 

 was independently discovered by Faber in the same year. Brieger and 

 Fraenkel's body consisted practically of an alcoholic precipitate from 

 filtered cultures in bouillon, and was undoubtedly toxic. Within recent 

 years such attempts to isolate tetanus toxins in a pure condition have 

 practically been abandoned, and attention has been turned to the 

 investigation of the physiological effects either of the crude toxin 

 present in filtered bouillon cultures, or of the precipitate produced from 

 the same by ammonium sulphate (cf. p. 167). 



The toxic properties of bacterium-free filtrates of pure cultures 

 of the b. tetani were investigated in 1891 by Kitasato. This 

 observer found that when the filtrate, in certain doses, was 

 injected subcutaneously or intravenously into mice, tetanic spasms 

 developed, first in muscles contiguous to the site of inoculation, 

 and later all over the body. Death resulted. He found that 

 guinea-pigs were more susceptible than mice, and rabbits less so. 

 In order that a strongly toxic bouillon be produced, it must 

 originally have been either neutral or slightly alkaline. Kitasato 

 further found that the toxin was easily injured by heat. Exposure 

 for a few minutes at 65 C. destroyed it. It was also destroyed 

 by twenty minutes' exposure at 60 C., and by one and a half 

 hours' at 55 C. Drying had no effect. It was, however, 

 destroyed by various chemicals such as pyrogallol and also by 



