Biological Therapy 



111 



Some, such as blackleg filtrate and aggressin, are used as 

 antigens for the production of antibodies while others, as 

 the tuberculins and mallein, are used for diagnostic pur- 

 poses. This latter use is possible on account of the hyper- 

 susceptibility which infected animals display for the by- 

 products of the bacteria with which they are infected. These 

 products are rendered free of bacteria by filtration during the 

 Course of production. This process of filtration prevents 

 any possibility of disease being reproduced by such filtrates. 



THE PEEPARATIOK OF PITMAN-MOORE IMMUNE 



SERA 



All of the recognized principles of modern biological 

 therapy are exercised in the production of this line of im- 

 mune sera. 



These products, twelve in number, are prepared for the 

 treatment of animals affected with, or for passive immuni- 

 zation against, an equal number of specific diseases. These 

 sera which may be either anti-bacterial or antitoxic are all 

 made from the blood of specially selected healthy young 

 horses which are used only for this purpose. After being 

 subjected to thorough physical and biological examinations 

 to prove their freedom from disease, each horse is immun- 

 ized against one specific kind of organism and after immuni- 

 zation, is subjected to a series of injections with the toxin 

 or living organisms against which it is to produce an im- 

 mune serum. The number of bacteria injected is gradually 

 increased with each injection until the animal is capable 

 of withstanding overwhelming amounts of what, under ordi- 

 nary circumstances, would be life destroying bacteria. 



In the production of antitoxin, the horses eventually 

 receive injections of toxin, hundreds of times stronger than 

 an ordinarily fatal amount. These repeated injections are 

 followed by stimulation of the body cells, resulting in anti- 

 body production which eventually becomes excessive, as a 

 result of which the blood stream becomes laden with the 

 specific protective bodies. At the proper time a small amount 

 of blood is drawn from each horse to determine the amount 

 of antibody production, or, in other words, the potency of the 

 serum. This is spoken of as a "trial bleeding." 



If, upon test, this proves satisfactory, the animal is bled 

 from the jugular vein, several quarts of blood being with- 



