388 TETANUS. 



during the advancing liquefaction of the gelatine. Thus 

 peptic digestion and toxine formation are apparently due 

 to different vital processes on the part of the tetanus 

 bacillus. 



A strong though not conclusive argument in favour of 

 a ferment being concerned in the toxine production, is 

 derived from the occurrence of a definite incubation period 

 between the introduction of the toxine into an animal's 

 body and the appearance of symptoms. The incubation 

 period varies according to the species of animal employed, 

 and the path of infection. In the guinea-pig it is from 

 thirteen to eighteen hours, in the horse five days, and the 

 incubation is shorter when the poison is introduced into a 

 vein than when injected subcutaneously. The interpreta- 

 tion put on the occurrence of this period of incubation by 

 the upholders of the ferment theory has been that a time is 

 required for the supposed diastase to elaborate from the 

 tissues albumoses, which are the immediately toxic agents. 



Whatever the nature of the toxine is, it is undoubtedly 

 one of the most powerful poisons known. Even with his 

 probably impure toxalbumin Brieger found that the fatal 

 dose for a mouse was .0005 of a milligramme. If the 

 susceptibility of man be the same as that of a mouse, 

 the fatal dose for an average adult would be .23 of a milli- 

 gramme or about ^uWti 18 of a grain. 



With regard to the action of the toxine it has been shown 

 to have no effect on the sensory or motor endings of the 

 nerves. It acts solely as an exciter of the reflex excitability 

 of the motor cells in the spinal cord. The motor cells in 

 the pons and medulla are also affected, and to a much 

 greater degrfee than those in the cerebral cortex. When 

 injected subcutaneously the toxine probably to a certain 

 extent is absorbed into the sheaths of the nerves, and 

 thence finds its way to that part of the spinal cord from 

 which these nerves spring. This explains the fact that in 

 an animal the tetanic spasms appear first in the muscles of 

 the part in which the inoculation has taken place. It is 

 doubtful whether such absorption takes place in tetanus 



