194 THE TOXINS PRODUCED BY BACTERIA 



bodies which show characteristic toxic properties, but which had 

 the reactions neither of peptone, albumose, nor albuminate, and 

 the nature of which is unknown. It has also been found that 

 the bacteria of tubercle, tetanus, diphtheria, and ( cholera can 

 produce toxins when growing in proteid-free fluids In the case 

 of diphtheria, when the toxin is produced in such a fluid a proteid 

 reaction appears. Of course this need not necessarily be caused 

 by the toxin. Further investigation is here required, for 

 Uschinsky, applying Brieger and Boer's method to a toxin so 

 produced, states that the toxic body is not precipitated by zinc 

 salts, but remains free in the medium. If the toxins are really 

 non-proteid they may, on the one hand, be the final product of 

 a digestive action, or they may be the manifestation of a separate 

 vital activity on the part of the bacteria. On the latter theory 

 the toxicity of the toxic albumoses of Sidney Martin may be due to 

 the precipitation of the true toxins along with these other bodies. 

 From the chemical standpoint this is quite possible. When we 

 take into account the extraordinary potency of these poisons (in 

 the case of tetanus the fatal dose of the pure poison for a 

 guinea-pig must often be less than '00000 1 grm ), we can under- 

 stand how attempts by present chemical methods to isolate them 

 in a pure condition are not likely to be successful, and of their 

 real nature we know nothing. Friedberger and Moreschi have 

 shown that the intravenous injection in the human subject of 

 a fraction of a loopful of a dead typhoid culture gives rise 

 to toxic symptoms, including marked febrile reaction. Such 

 injections are followed by the appearance of agglutinating and 

 bacteriolytic substances in the serum. These results show that 

 intracellular toxins may be comparable with extracellular toxins 

 so far as concerns the extremely small dose sufficient to produce 

 toxic effects. 



Amongst the properties of the extracellular toxins are 

 the following : They are apparently all uncrystallisable ; they 

 are soluble in water and they are dialysable ; they are pre- 

 cipitated along with proteids by concentrated alcohol, and also 

 by ammonium sulphate; if they are proteids they are either 

 albumoses or allied to the albumoses ; they are often relatively un- 

 stable, having their toxicity diminished or destroyed by heat (the 

 degree of heat which is destructive varies much in different cases), 

 light, and by certain chemical agents. Their potency is often 

 altered in the precipitations practised to obtain them in a pure 

 or concentrated condition, but among the precipitants ammonium 

 sulphate has little if any harmful effect. Regarding the toxins 

 which are more intimately associated with the bacterial proto- 



