per c.c. One two-hundredth of a c.c. or .005 c.c. neutralized the 

 standardized toxin ; therefore each cubic centimeter of the serum 

 contained 200 units of antitoxin. '" 



Antitoxins are fairly stable bodies. When kept in a cool, dark 

 place they may be preserved for a year or more with very little 

 deterioration. It is customary for manufacturers to place a label 

 on each package bearing a date beyond which the serum is not 

 guaranteed to contain the original amount of antitoxin. 



The most important point in the administration of antitoxin 

 is that it be given as soon as possible after infection has occurred ; 

 2000 units on the first day that symptoms appear is considered 

 more efficacious than 5000 units on the second day. A total of 

 10,000 or even 20,000 units in severe cases is sometimes given. 



Prophylactic Immunization against Diphtheria. The sub- 

 cutaneous injection of antitoxin will afford protection for a limited 

 period to susceptible persons exposed to infection. The doses are 

 relatively small and the injection does not usually produce any 

 ill effects save a little soreness at the site of inoculation. Un- 

 fortunately antitoxin injected into the body is eliminated rather 

 rapidly, so that protection thus gained lasts only from two to four 

 weeks. As a prophylactic measure children under one year are usu- 

 ally given 500 units, older children and adults 1000 to 1500 units. 



Seeing that antitoxin produced by the body cells in direct 

 response to the presence of toxin remains for a much Ic-nger period 

 in the body than that injected from another animal, a method has 

 been advocated whereby the body cells may be stimulated to pro- 

 duce their own antitoxin in sufficient amounts to protect them- 

 selves in case of exposure to diphtheria. A mixture of toxin and 

 antitoxin known as T-A is injected in graded doses subcutaneously. 

 The method is based upon the principle that the union of toxin 

 and antitoxin is not stable, and when a neutral mixture of the two 

 is injected sufficient toxin may be dissociated to stimulate the body 

 cells to produce their own antitoxin. 



Schick Test. In order to determine whether a prophylactic 

 dose of antitoxin is necessary in case of exposure to diphtheria 

 Schick has devised a simple skin test for detecting the presence 



