PHYTOTOXIN IMMIXITY 145 



that one one-thousandth of a milligram (0.000001 gram) was fatal per 

 lilo of rabbit, and solutions of 0.001 per eent. would agglutinate red 

 corpuscles. The toxicity was also impaired or destroyed by tryptic 

 digestion. They consider that probably, because of its extremely 

 great toxicity, Jacoby was able to get active preparations that con- 

 tained too little active substance to give the protein reactions. As 

 they remark: "If one-thousandth of a milligram of a compound 

 giving on analysis every indication of being a relatively pure protein, 

 is phj^siologically active in the degree characterized by our experiments, 

 the toxicity of any impurity must be infinitely greater than tliat of 

 any known toxins." Against the claim that the toxic princii)le is 

 simply carried down with the protein is the fact that it does not come 

 down in the first fraction that is precipitated, the globulin, which usu- 

 ally carries down all impurities. All the ricin comes down between 

 the limits of one-fifth and one-third saturation with ammonium sul- 

 ]ihate, exactly as does the albumin. Field ^ has found evidence that 

 the agglutinin and toxin of pure ricin are separable, but Reid believes 

 them identical. Of 21 varieties of ricinus seeds examined by Agul- 

 hon,^^ all yielded hemagglutinins. During germination of the castor 

 bean the ricin disappears with the albumin.^'' Ricin agglutinates not 

 only corpuscles, but tissue cells of all sorts, and causes precipitates in 

 normal serum.'* Curcin alone seems to have no hemagglutinative 

 action.*^ 



Immunity. — The phytotoxins have been very serviceable in the 

 study of immunity, since they obey the same laws as bacterial toxins 

 and can be handled in more definite quantities. By their use Ehrlich 

 first determined that toxin and antitoxin act quantitatively. They 

 seem to possess haptophore and toxophore groups, and immunity is 

 readily obtained against them, not only by subcutaneous injection, 

 but by dropping into the conjunctival sac, and also by feeding, show- 

 ing their direct absorbability and their resistance to digestion. The 

 antitoxin is present in the milk of the immunized mother and im- 

 munizes the suckling; but little is carried through the placenta into 

 the fetal blood. The immunity is specific, ricin antitoxin, for exam- 

 ple, not protecting against abrin (although it is said to protect against 

 robin). Roemer found that in animals immunized by conjunctival 

 application the eye so used became immune to the local action of the 

 poison before the other eye did, indicating a local development of 

 immune substance. In general immunization the immune substance 

 appears first in the spleen and bone-marrow. Normal serum gives 

 a precipitate with ricin, but immune serum gives a much heavier one. 



3 Jour. Exper. Med., 1910 (12), o.il ; Keid, Landwirtsch. Versuchst.. 101.3 (F2), 

 393. 



3a Ann. Inst. Pasteur. 1014 (28). SIO. 

 3bA<TuIhon, ibid., 101.5 (20). 2.37. 



4Michaelis and Steindorff. Biocliem. Zeit.. 1000 (2), 43. 

 4aFelke, Landwirts. Versuchst., 1913 (82), 427. 

 10 



