PHYSIOLOGICAL AND BIOLOGICAL RELATIONS 93 



could be immunised against ricin and abrin and that an animal im- 

 munised against abrin is still sensitive to ricin, thus showing the two 

 substances to be different. 



Ehrlich's discovery was soon followed by numerous investigations 

 of the physiological effects of these toxalbumins which were then re- 

 cognised to have close relations to the bacterial poisons \cf. Schaer 

 (449), Tichmiroff (545), Werhovsky (568), Stepanoff (523), Ehrlich 

 (103), Heuseval (159), Robert (199), Lau (216), Roemer (435), 

 Hausmann (151), Jacoby (174), Kraus (209), Rehns (390, 391), Braun 

 and Behren (58), Brieger (59), Arrhenius (16), Fraenkel (124), Jacoby 

 (175), Jodlbaur (178), Pascucci (372), Woronzow (580), Sachs (444), 

 Cornevin (79)]. 



Siegel (516) discovered and described in 1893 atoxic substance 

 from the seeds &i Jatropha curcas which he named curcin. 



Elfstrand (109) discovered in 1897 another toxic substance in the 

 seeds of Crotin eluteria which appeared to be of protein nature and to 

 which he gave the name crotin. This substance agglutinated the 

 blood corpuscles of certain animals and was toxic. The preparation 

 contained both albumin and globulin and Elfstrand supposed that 

 both were toxic substances. The toxicity was destroyed by heating 

 their solution to 70 and also by pepsin digestion. 



In 1898 Cushny (82) undertook an extensive study of various 

 methods for isolating ricin and obtained preparations of much greater 

 toxicity than those before described. All his attempts to separate a 

 toxic substance from the protein preparations failed, and he states that 

 when the preparation contained protein it was toxic, but when the pro- 

 tein was removed it was not. He ascribed the failure of his predeces- 

 sors to detect protein reactions in solutions which were highly toxic to 

 the fact that the ricin is fatal in such extremely small amounts that 

 such solutions were too dilute to give a protein reaction. He con- 

 cludes that ricin is either a protein or is so intimately associated or 

 combined with the protein that it could not be separated by any of 

 the means then available. As evidence of its protein nature he found 

 that it was precipitated by saturating its solutions with ammonium 

 sulphate, was coagulated by heating its solutions and thereby rendered 

 non-toxic, and that the toxicity of the solutions decreased as the pro- 

 tein was removed from them. He further found that saturation with 

 magnesium sulphate removed all of the ricin from its solution, and that 

 the albumose which was not thus precipitated had no toxic or aggluti- 

 nating properties. 



In 1901 Power (381) discovered and described a somewhat similar 



