232 ANTITOXINS 



hand. This delay of twenty-four hours before immunizing with anti- 

 toxin is justifiable unless a contact shows clinical signs suggestive of 

 diphtheria. In such an instance we believe that antitoxin should be 

 given as soon as possible. 



The test has a special field of usefulness in hospitals and institutions 

 for the care of children. All children should be subjected to the toxin test 

 prior to admission, and those immunized who react positively. 



I have applied this test to over 700 persons of various ages with the 

 following reactions: 



Under 1 year 15 per cent, positive; 85 per cent, negative. 



Ito 2 years 43 " " 57 



2 to 4 years. 66 " " 34 



4 to 6 years 58 " " 42 



6 to 8 years 51 " " 49 



8 to 15 years 24 " " 76 



15 to 30 years 40 " " 60 " 



Over 30 years 26 " " 74 



In scarlet fever, measles, and acute anterior poliomyelitis the per- 

 centage of positive reactions is increased. 



The percentage of negative reactions is of particular interest as indi- 

 cating the number of persons who are naturally immune to diphtheria 

 on the evidence of this test, and showing the value of the reaction, es- 

 pecially in institutions for children where a large number may be exposed, 

 and requiring prophylactic injection of antitoxin unless known to be 

 naturally immune to the disease. If it is the custom to reinject with 

 antitoxin a month or six weeks later, it is better practice to apply the 

 toxin test first and administer serum to those only who show a positive 

 reaction. This means a saving of antitoxin and the avoidance of the 

 discomfort attending the injection of serum and disagreeable serum 

 sickness. 



Specificity of Antitoxins. Antitoxins well illustrate the law of 

 specificity that exists between antigen and antibody, since they are 

 strictly specific for their toxins. Diphtheria antitoxin will neutralize 

 only diphtheria toxin; tetanus antitoxin, only tetanus toxin, and so on 

 through the list. This specificity is not confined to the particular 

 toxin-producing organism that generates the antitoxin; for example, 

 there are various kinds of diphtheria bacilli, differing as regards 

 morphology and toxicity, although one antitoxin appears to act the same 

 with their various toxins. 



Nature of the Toxin- Antitoxin Reaction. While the injection of toxin- 

 antitoxin mixtures into the lower animals is the only practical method 

 of testing and standardizing the curative and prophylactic powers of 



