ANTITOXINS 5 



theria antitoxin, when stored in vials and kept in a cool 

 place away from light and air contains within 10 per 

 cent of its original strength for at least two months; 

 after that it can be used by allowing for a maximum 

 deterioration of 3 per cent for each month. 



Testing the Strength of the Antitoxin. This is carried 

 out as follows: Six guinea pigs are injected with mix- 

 tures of toxin and antitoxin. In each of the mixtures 

 there is 100 times the amount of a toxin (similar to 

 that adopted as the standard) which will kill a 250 

 grams on an average in 96 hours. In each of the 

 mixtures the amount of antitoxin varies; for instance, 

 No. i would contain 0.002 cc. serum; No. 2, 0.003 cc -> 

 No. 3, 0.064 cc.; No. 4, 0.005 cc -> etc - If at the en( ^ f 

 the fourth day Nos. i, 2 and 3 were dead and Nos. 4, 

 5 and 6 were alive we would consider the serum to 

 contain 200 units of antitoxin for each cubic centi- 

 meter. When we mix only ten fatal doses of toxin 

 with one-tenth ok the amount .of antitoxin used with 

 100 fatal doses, the guinea pig must remain well. The 

 mixed toxin and antitoxin must remain together for 

 fifteen minutes before injecting. 



Behring's publication was followed in the next 

 two years by considerable work along these lines, 

 valuable contributions being made by Aronson, 1 

 Roux, and Martin, 2 Wernicke, 3 Knorr 4 and others. 

 The statements of Behring as to the strict specifi- 

 city of the antitoxins were fully confirmed. Certain 



1 Berliner med. Gesellschaft, Sitzung, Dec. 21, 1892. Also 

 Berliner Klin. Wochenschrift, 1893 and 1894. 



2 Roux and Martin, Annal. Pasteur 1894. 



3 Behring and Wernicke, Zeitsch. Hygiene, 1892. Vol. xi. 



4 Behring and Knorr, Zeitsch. f. Hygiene, 1893. Vol. xii. 



