44 MODERN BIOLOGIC THERAPEUSIS 



rum, the formation of a flocculent precipitate 

 can frequently be observed. The antibodies re- 

 sponsible for this phenomenon are called pre- 

 cipitins or coagulins. The precipitin reaction 

 is the only directly visible result of the combina- 

 tion of antibodies with soluble antigens, but 

 there is evidence that other changes take place. 

 Another evidence of the action of immune se- 

 rum is that a soluble toxin combined with the 

 corresponding serum is rendered harmless ap- 

 parently without disintegration of the toxin. 

 The neutralizing substance merely prevents the 

 toxin from uniting with the tissue-cells, and is 

 called antitoxin. 



Source It has been found that after injec- 

 tion of antigen, the spleen, bone marrow and 

 lymph nodes show increase of antibodies before 

 the blood which, however, soon gains more and 

 more, while the tissues mentioned gain rela- 

 tively less. The most natural conclusion would 

 seem to be that the antibodies are formed in the 

 blood-making organs, and the result of splenec- 

 tomy certainly favors this view. Loss of blood 

 increases the output of antibodies and this also 

 points to the blood-making organs as their 

 source. 



