THE KI'irilAMS h'KACTlOX 209 



positive reaction, after two hours' incubation of the reacting mixture; 

 the increase is seldom above eight drops. This reaction is said to be 

 sharply specific and extremely delicate, detecting antigens diluted \\\) 

 to 1 in 100,000,000 or more. The antigens used are soluble in alcohol, 

 but their nature is unknown ; the antibody involved in the reaction is 

 referred to as the meiostagmin, but its relation to other antibodies is 

 likewise unknown. 



THE EPIPHANIN REACTION 



Besides reduction in surface tension, other physico-chemical changes 

 result from antigen-antibody reactions, including the rate of diffusion, 

 the osmotic pressure, and, in consequence, according to Weichardt, 

 the neutral point to phenol-phthalein of a mixture of barium hydrox- 

 ide and sulphuric acid, is also changed towards the acid side by anti- 

 gen-antibody reactions taking place in the mixture.'^- This phenom- 

 enon has been utilized by Weichardt, under the name of "epiphanin 

 reaction," to determine the occurrence of such interaction of antigen 

 and antibody. The reaction probably depends upon absorption phe- 

 nomena, but the exact nature of the change is not yet understood. 

 According to Rosenthal," the epiphanin reaction is especially suitable 

 for demonstrating cancer antibodies and antigens, but Burmeister ^* 

 and others have not been successful with this procedure. 



52 See Weichardt. Berl. klin. Woch., 1911 (48), 1935; Rosenthal, Zeit. Im- 

 nuinitat., 1912 (13), 383; Angerer and Stotter, Miinch. med. Woch., 1912 (59), 

 2035. 



53 Zeit. Chemotherapie, 1912 (1), 156. 



54 Jour. Infec. Dis., 1913 (12), 459. 



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