424 TETANUS 



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. 195). 



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 

 sunlight. 



In anaerobic bouillon cultures the maximum toxicity is de- 

 veloped in from ten to fifteen days. Behring pointed out that 

 after the filtration of cultures containing toxin, the latter may 

 very rapidly lose its power, and in a few days may only possess 

 yj^th of its original toxicity. This he attributed to such factors 

 as temperature and light, and especially to the action of oxygen. 

 Toxins should thus have a layer of toluol floated on the surface 

 and be kept in a cool, dark place. The effect of harmful agents 

 on the crude toxin is apparently to cause a degeneration of the 

 true toxin so as to form what it is convenient at present to call 

 toxoids similar to those produced in the case of diphtheria toxin, 

 and it is also true here that the toxoids while losing their 

 toxicity may still retain their power of producing immunity 

 against the potent toxin. Further, altogether apart from the 

 occurrence side by side in the crude toxin of strong and weak 

 poisons, it has been shown that such crude toxin contains toxic 

 substances of probably quite a different nature. Ehrlich has 

 shown that besides the predominant spasm-producing toxin 

 (called by him tetanospasmin), there exists in crude toxin a 

 poison capable of producing the solution of certain red blood 

 corpuscles. This hsemolytic agent he calls tetanolysin. It does 

 not occur in all samples of crude tetanus toxin, nor is it found 



