PRODUCTION AND TESTING OF ANTITOXINS 



223 



4 c.c. with salt solution in order to equalize the conditions of concen- 

 tration and pressure. The mixtures are then kept for one hour at 

 room temperature in diffused light. After this they are subcutaneously 

 injected into a series of guinea-pigs weighing from 300 to 400 grams. 

 The following example of a test is taken from the article by Rosen? i 

 and Anderson quoted above. 



In this series the guinea-pig, receiving 0.0015 c.c. of the antitoxin, died 

 in approximately four days; 0.0015 c.c. therefore represents one-tenth 

 of an immunity unit. 



In therapeutically employing antitoxin for prophylactic purposes, 

 about 1,500 units should be employed. 



