The production of immune sera follows 

 along much the same lines for both antitoxic 

 and antibacterial sera. There are, however, 

 three distinct differences in the methods: (1) 

 For the production of antitoxic sera, the solu- 

 tion of toxin is used as antigen with which the 

 horse is immunized, whereas in the production 

 of antibacterial sera, cultures of the specific 

 bacteria are used. (2) In America, antitoxic 

 sera are usually refined and concentrated and 

 the antibacterial sera are not. In order to 

 designate the refined and concentrated product 

 and to distinguish the refined from whole serum 

 which formerly was used, the antitoxic sera 

 are usually termed Diphtheria Antitoxin and 

 Tetanus Antitoxin. (3) The method of stand- 

 ardizing the antitoxic sera differs from that 

 of testing the antibacterial sera, inasmuch as 

 there is a definite and generally accepted unit 

 of immunity established for the antitoxic sera. 



Outline of Method In the preparation of 

 65 



