DIPHTHERIA 49 



is fixed by the cellular tissue but may also be fixed by nervous 

 tissue. The preventive vaccination of children by mixtures 

 of toxin and antitoxin may have, as noted by L. Martin 1 

 consequences which are disagreeable if not serious. The 

 susceptibility of the horse is intermediary between that of 

 man and of the guinea-pig. In a horse treated by diphtheria 

 toxin nervous symptoms are less common than in man. 

 Edema of the subcutaneous cellular tissue develops in almost 

 the same way as in the guinea-pig. 



We may thus explain why an exactly neutral mixture, that 

 is, one which contains no excess of antitoxin but may contain 

 an excess of toxin which is not pathogenic for the guinea-pig 

 will be also neutral for the horse, slightly pathogenic for 

 man, more so for the rabbit, and frankly toxic for birds which 

 are the most sensitive animals. For the same reasons, fixa- 

 tion of diphtheria toxin by cellular tissue should be considered 

 a reaction of preservation against reactions more pathogenic 

 for nervous tissue. The larger and stronger the barrier 

 which holds toxins in place in cellular tissue, the less will be 

 the chance for these toxins to approach nervous tissue. 



The total of these facts permits us to represent the patho- 

 genicity and evolution of diphtheria in the following manner. 

 Toxins secreted by bacteria are developed in the mucous 

 membranes of the throat, penetrate to the subjacent cellular 

 tissue and combine with the normal antibody of this tissue. 

 The two extreme things which may then happen are : 



1. The quantity or the virulence of the toxin secreted may 

 correspond exactly to the quantity of normal antibody which 

 can neutralize and digest it without difficulty and there will 

 thus be local immunity; and if the process lasts long enough 

 for the antibody to be able to reproduce itself in excess and 

 to pass into the blood as antitoxin there will also be general 

 immunity. 



2. The quantity or the virulence of the secreted toxin or 

 rather the rapidity of the secretion may be too great for the 

 cellular tissue to be able to fix and retain it, so that a part of 

 this toxin will then pass into the organism and will produce 



1 Loc. cit. 



