Artificial immunity against toxins 385 



alive long enough to complete the experiment. We must, therefore, 

 for the present, be content with indirect arguments. If the nerve 

 centres do really produce the tetanus antitoxin and excrete it into 

 the blood, we ought at a given moment to find in these organs a 

 greater quantity of this substance than in the blood and the other 

 organs. The reader will recall the researches of Pfeiffer and Marx, 

 and of Deutsch, who demonstrated the possession of a greater richness 

 in protective substance by the phagocytic organs of animals, treated 

 with micro-organisms, than by the blood serum. The same result 

 might be obtained by a comparative investigation of the tetanus 

 antitoxin in the nerve centres and the blood of animals immunised 

 against tetanus. My experiments directed to this point have not 

 been favourable to the hypothesis of the nervous origin of tetanus 

 antitoxin. 



In fowls, killed as soon as tetanus antitoxin began to appear in 

 the blood, the brain and spinal cord did not exhibit the slightest 

 antitoxic power 1 . We might be tempted to explain this result as due 

 to an accumulation of toxin in the nerve centres which would prevent 

 the manifestation of the antitoxin. For this reason, in my later 

 researches 2 , I made use of animals that had been long immunised, 

 but whose blood was still antitoxic. I killed a fowl which had not 

 received any toxin for about eight months, and a guinea-pig into which 

 the last toxic injection had been made almost two years before the 

 date of this experiment. After removing a portion of the brain the 

 blood of these two animals was found to be more antitoxic than 

 before the operation, which indicated that the source of the antitoxin 

 was as yet uninjured. To ascertain whether this source was to be 

 found in the nerve centres I made a comparative determination of the 

 antitoxic power of the brain, of the spinal cord and also of several 

 other organs, of the blood and of the exudations. The result was 

 still negative. The nerve centres were found to be less antitoxic 

 than the blood and other fluids of the body, and even less active than 

 such organs as the liver and kidneys. 



In support of the hypothesis of the nervous origin of tetanus [405] 

 antitoxin there remains, then, only the fact of the retarding action 

 of the cerebral substance upon tetanus. In the absence of other 

 arguments this assumes a preponderating importance. We have seen 

 that this action is based on a fleeting and not very firm fixation of the 



1 Ann. de Flnst. Pasteur, Paris, 1897, t. xi, p. 801. 



2 Ann. de VInst. Pasteur, Paris, 1898, t. xn, p. 81. 



B. 25 



