384 TETANUS. 



the bacilli by themselves can form toxins in the body and pro- 

 duce the disease. Further, if a small quantity of garden earth 

 be placed under the skin of a mouse, or better that of a white 

 rat, death from tetanus takes place in a great many cases. 

 [Sometimes, however, in such circumstances death occurs with- 

 out 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, sup- 

 plemented 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 culture in bouillon, and was undoubtedly toxic. 

 Within recent years such attempts to isolate tetanus toxins in a pure condi- 

 tion 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. 176). 



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 pro- 

 duced, it must originally have been either neutral or slightly 

 alkaline. Kitasato further found that the toxin was easily in- 

 jured 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 pyro- 



