ANTI-ENZYME IMMUNITY 315 



Osborne, Mendel and Harris (1905) prepared a highly pure ricin 

 of which 0.001 mg. per kg. was fatal to a rabbit. It was obtained by 

 extracting the pressed cake of castor oil plant seeds with 10 per cent 

 sodium chloride. The extract on dialysis yielded a globulin precipitate 

 which was discarded. When the supernatant was treated with ammo- 

 nium sulfate, ricin precipitated out. The precipitate was dissolved and 

 reprecipitated with ammonium sulfate, followed by dialysis which gave 

 them an albuminous substance with the above highly toxic properties. 

 They established the protein nature of the toxin. They further found 

 that 0.01 to 0.007 per cent ricin solution was effective in causing the 

 agglutination of the red blood corpuscles of various animals. Karrer, 

 et al. (1924) in an extensive study attempted to improve the purity of 

 the ricin prepared by Osborne, et al,; but, they failed to obtain a purer 

 preparation. Karrer et al. for purification purposes employed methods 

 such as adsorption on kaolin, aluminum hydroxide and precipitation by 

 metallic salts. Confirming the observation of Osborne, et al., they also 

 found that the loss of toxicity ran parallel with the proteolytic hydrol- 

 ysis of ricin. In the proteolytic digest, part of the ricin was found to re- 

 main undigested which was isolated and shown to be biologically not 

 different from the original ricin. Chemically the undigested ricin con- 

 tained 2.5 to 3 per cent lower total nitrogen which was entirely ac- 

 counted for by the possible splitting of the arginine guanidine group 

 and thereby the conversion of arginine into ornithine groups. However, 

 this change produced no decrease or loss of toxicity in the ricin mol- 

 ecule. 



b. Inhibition of Lecithinase and Hemolytic Activities of Ricin by 

 Anti-Ricin Immune Serum. In 1 897 Ehrlich showed that the action of 

 a solution of ricin in vitro on citrated blood causes clumping and the 

 precipitation of the corpuscles. He further showed that this action 

 could be completely done away with by previously mixing with the 

 ricin definite quantities of anti-ricin serum. Mixtures of the toxin and 

 antitoxin which did not clump were found by Ehrlich to be innocuous 

 on injection into mice. His test tube experiments were farther found 

 to represent with much accuracy occurrences within the animal body. 



Rehns (1902) reported that ricin adsorbed on red blood corpuscles 

 was neutralized and removed with anti-ricin serum. The recovered 

 ricin possessed all its agglutinating, antigenic and toxic properties. 

 Conversely Madsen and Walbum (1904) reported that, depending 



