TETANUS TOXINE. 115 



The motor, sensory, and sympathetic nerves are equally suit- 

 able for the attack, according to MORAX and MARIE, although 

 according to MEYER and RANSOM the normal axis cylinder is the 

 exclusive conveyor of the poison, which reaches it only by way 

 of the nerve end plates on the muscle and not through the blood. 

 The poison is only distributed in a centripetal direction. MEYER 

 and RANSOM also found that, in addition to severance of the 

 nerves, injection of antitoxins into them prevented the poison 

 from reaching the spinal cord. This happened with certainty in 

 local (subcutaneous) poisoning, and sometimes also after intra- 

 venous injection. The centres belonging to the protected nerves 

 remain free, while the animal suffers from general tetanus. 

 Even in the spinal cord itself severance can prevent the further 

 distribution of the poison. In the case of animals thus treated 

 no poisoning of the brain occurred ; they lay for three weeks in 

 a continuous tetanic state and eventually died apparently from 

 exhaustion. The direct transmission of the poison by way of 

 the nerves appears the more probable from the fact that when 

 directly injected into the nerves its action is much more intense 

 (about ten times as much). In these experiments any quantities 

 of poison which might possibly have passed into the lymph 

 glands or blood on injection, were in each case neutralised by 

 large quantities of antitoxine. The period of incubation is 

 considerably shortened, and if the injection is made directly 

 into the lumbar cord it is reduced to a few hours, as had already 

 been shown by the experiments of Roux and BoRREL 1 on 

 tetanus in the head. The variations in the length of the 

 incubation periods (vide supra) are explained by the slow trans- 

 mission through the nerves. 



It follows from these experiments that the poison is first 

 transmitted exclusively by the nerves themselves to the centres 

 of the spinal cord, and that the specific symptoms are produced 

 by these. If the poison attacks only the sensory centres, there 

 results a simple tetanus dolorosus without convulsions. It also 

 results from this strict differentiation that the poison does not 

 reach the spinal cord by way of the blood or lymph channels. 

 Under normal conditions the poison only reaches the motor 

 ganglia by way of the motor neuron, and produces there a 

 condition of over-excitability towards the usually latent stimuli 

 which proceed from the sensory neurons. This is not the place 

 to go further into the theory of tetanus itself. 



The usual point of attack of tetanus poison, and so of the 

 disease, is thus the spinal cord. But it is not exclusively the 



'Roux and Borrel, " T<5tanos Cerebral," Ann. Past., xii., 225, 1898. 



