So (144) Society for Experimental Biology and Medicine. 



lable protein and never with those free from the albumin already- 

 mentioned. The toxicity of the products consisting chiefly of this 

 albumin was extremely great, the most active preparation proving 

 fatal when administered subcutaneously to rabbits in the small dose 

 of 0.0005 mg. per kilo of body- weight. Each sample of ricin pre- 

 pared by the authors showed in marked degree characteristic agglu- 

 tinating properties in its behavior toward erythrocytes ; and the 

 pathological findings after intoxication were typical. The other 

 proteins of the seed are devoid of the properties noted for ricin, 

 thus demonstrating the applicability of the methods of separation 

 employed. The toxicity of the active preparations is proportional 

 to the content of coagulable albumin, the purest specimens con- 

 taining, as their analysis shows, little else than protein. Thus far 

 their determinations have shown that the ricin prepared by the 

 authors does not differ from ordinary proteins in composition, heat 

 coagulation, color reactions, precipitation reactions, specific rota- 

 tion, or in the state of combination of its nitrogen. By tryptic 

 digestion the agglutinating power and toxicity of pure ricin may 

 be greatly impaired or destroyed. The experience of the authors 

 lends no encouragement to the attempts to " purify " such toxins 

 by methods designed to eliminate protein substances from the active 

 materials. 



40 (86). " On a method of determining indol," with demon- 

 strations : C. A. HERTER and M. LOUISE FOSTER. 



The method described by the authors constitutes a rapid and 

 accurate means of determining indol. It is based on the fact that 

 indol, in slightly alkaline solution, readily condenses with naphtho- 

 quinon sodium mono-sulfonate, and forms a blue crystalline com- 

 pound which is only very slightly soluble in water and is readily 

 extracted by chloroform from a watery solution or suspension. 

 The condensation compound results from the union of two mole- 

 cules of indol with one of the naphthoquinon compound. The union 

 does not occur as in the case of compounds with amins, with the 

 elimination of the sulfonic acid group, but occurs between one of 

 the carbonyl groups of the naphthoquinon compound and the imid 

 group of the indol. The new compound is, therefore, a di-indyl 

 naphtho-ketone mono-sulfonate. The solubility of this substance 

 in chloroform is about one part in 4,000 of the solvent, and is suffi- 



