70 THE PRINCIPLES OF IMMUNOLOGY 



ceptibility." The element of hypersusceptibility in this connection 

 will be deferred until after the presentation of the fundamental 

 material on anaphylaxis and hypersusceptibility. The following 

 paragraphs will present briefly the essentials concerning ricin, abrin, 

 robin, crotin, curcin, and phasin. This brevity is justified by the rela- 

 tively small practical importance of these substances. 



Ricin is the toxic principle of the castor-oil bean, ricinus com- 

 munis. It was isolated by Gibson in 1887 and named ricin by 

 Stillmark in 1888. Gushing made very strong toxic preparations and 

 Field states that ricin will kill rabbits in doses of o.oooi mg. per 

 kilo ; guinea-pigs, 0.0008 mg. ; dogs, 0.0006 mg. ; cats, 0.0002 mg. ; and 

 goats, 0.003 mg. Following injection there is an incubation period 

 succeeded by diarrhea, somnolence, weakness of extremities, and 

 death. At the necropsy are found reddening and swelling of Peyer's 

 patches, mesenteric and retinal hemorrhages, ulcers of stomach, 

 nephritis, general lymphatic swelling, and softening and degenera- 

 tion of the pyramidal cells of the cerebral cortex. Beauvisage re- 

 ported 150 cases of ricin poisoning in man of which nine were fatal. 

 Many of these were children who ate the seeds, but there were also 

 soap makers who handled the beans in soap manufactories. Ricin 

 and the other toxins in the group may be precipitated with the pro- 

 teins by ammonium sulphate ; they are precipitated by alcohol and are 

 gradually destroyed by proteolytic enzymes. Jacoby, however, 

 claims to have produced ricin and abrin which failed to give pro- 

 tein reactions. Osborne, Mendel, and Harris maintain that ricin is 

 inseparably associated with protein, and that Jacoby's error was 

 due in all probability to the fact that he obtained a product so toxic 

 that the small amounts necessary for toxic action were too small to 

 give the protein reactions. The most striking character of ricin in 

 vitro is its capacity to agglutinate the red blood-corpuscles of prac- 

 tically all warm-blooded animals. It may agglutinate other body 

 cells, precipitates protein, and is adsorbed by casein, fibrin, coagu- 

 lated serum albumin, and by silk. Jacoby concludes that ricin is a 

 mixture of agglutinin and toxin, the two having certain molecular 

 groups in common. Ehrlich believes that these may undergo altera- 

 tion into agglutinoid and toxoid. The mechanism of the agglutina- 

 tion is not clear and many hypotheses, none quite satisfactory, have 

 been advanced. Ehrlich produced an antiricin by giving increasing 

 doses to animals by mouth, and then changing to subcutaneous in- 

 jections. This antiricin was used by Ehrlich in the development of 

 much of his hypothesis of the toxin antitoxin union because of the 

 ease of manipulation as compared with the time-consuming and 

 expensive method of working with animal injections of toxin anti- 

 toxin mixtures. In addition to the antitoxin there are present in the 

 serum a closely related antiagglutinin (with which Ehrlich worked) 

 and a precipitin for ricin solutions. 



Abrin is obtained from paternoster or jequirity bean, abrus pre- 

 catorius, and was described by Warden and Waddell in 1884. It is 



