THE TOXINS 161 



fibrin. If we compare it to the diastases, we do so without 

 forming any rash opinion as to its chemical action and 

 simply in order to sum up some of its properties." This 

 reservation still holds good. 



The disappearance of the toxic property by heating to 60° does 

 not necessarily mean the destruction of a diastase. Heating 

 modifies the reaction of the fluids, especially of organic fluids, 

 and coagulates the proteins : this coagulation may inhibit the 

 action of certain substances or properties without destroying 

 them. The toxins have a character possessed neither by 

 chemical poisons, e.g., strychnine or potassium cyanide, nor by 

 the diastases : the action of these chemical poisons is almost 

 instantaneous, and a zymase put into a solution of sugar begins to 

 ferment it at once. The toxins, on the other hand, when injected 

 into the body, only manifest themselves after a silent period of 

 apparent inactivity, the period of incubation. By changing 

 the path of introduction, e.g., by injecting intravenously instead 

 of subcutaneously, and by increasing the dose, the period of 

 incubation may be rendered shorter : it is never reduced to 

 zero. Further the minimum incubation period varies with the 

 species of animal inoculated. 



It is admitted that the tetanus poison, to reach the nerve- 

 centres, has to travel along the peripheral nerves from the site 

 of its production, and within certain limits the period of 

 incubation varies in proportion to the distance of this : but even 

 when this delay is cut out the incubation period does not 

 reach zero. Meyer and Ransom inoculated the nerve-centres 

 of cats directly and still found a minimum incubation of three 

 to five hours. 



This inevitable incubation period suggests that the toxin of 

 the culture is not the poison which kills the animal, but that 

 the toxin inoculated undergoes in the body certain transforma- 

 tions (fermentations ?) which produce the true poison, the 

 action of which is direct and immediate. This secondary poison 

 was said to have been demonstrated by inoculating mice with 

 extracts of the organs of animals actually in tetanus, but these 

 experiments have not given constant results as the symptoms 



