TOXINS OF THE TETANUS BACILLUS 383 



the corresponding cells of the other side, and if still further 

 excess is present it passes up the cord to higher centres. The 

 affection of such higher centres can be prevented by section of 

 the cord. Meyer and Ransom hold that when toxin is injected 

 subcutaneously or intravenously, it only acts by being absorbed 

 by the end-plates in muscles and thence passes to the cord, and 

 they consider that the incubation period is to be explained by the 

 time taken for this extended passage to occur.) In this connection 

 they point out that it is in the larger animals, where the nerve 

 path is longest, that the incubation period is also long. Like 

 Marie and Morax, they believe that absorption of toxin by its 

 bathing the lateral aspects of uninjured nervous structures does 

 not occur, and in support of this they bring forward the 

 observation that when intravenous injection is practised, the 

 occurrence of tetanus in a part of the body can be precipitated by 

 such a slight injury as may be caused by the injection of a drop 

 of normal saline into the corresponding part of the cord. With 

 regard to the action of tetanus toxin, Meyer and Ransom believe 

 that there is a double effect on the nerve cells ferst, an exaggera- 

 tion of the normal tonus, which accounts for the continuous 

 stiffness of the muscles, and secondly, an increase in reflex 

 irritability, which is a prominent factor in the recurring spasms'^ 

 While no absorption of toxin takes place by sensory filaments, 

 they have found evidence of sensibility of the sensory apparatus 

 in the occurrence of what they call {tetanus dolorosus) This is a 

 great hypersesthesia and a paroxysmal hyperalgesia which can be 

 caused by injecting toxin into the spinal cord or into a sensory 

 root on the spinal side of the posterior root ganglion. These 

 symptoms are unaccompanied by motor spasms, but the animal 

 may die from exhaustion. The same observers have also made 

 interesting observations on the action of antitoxin. They found 

 that the injection of this substance into the course of a mixed 

 nerve could prevent toxin from passing up to the cord, but that if 

 antitoxin were injected even in great excess intravenously, and a 

 short time thereafter toxin were introduced into a nerve, the 

 death of the animal was not prevented. This they attribute 

 to the fact that antitoxin can only neutralise the toxin which is 

 still circulating in the blood. This is a very far-reaching 

 conclusion, as it throws doubt on what has been held to be a 

 possibility, namely, (that toxin can be actually detached from 

 cells in which it is already anchored^ But a still more 

 significant observation was made, for in one case of an animal 

 actively immunised against tetanus, and which contained in its 

 serum a considerable quantity of antitoxin, the injection of toxin 



