A Toxic Nucleoproteid from Rat Carcinoma. 63 



that the presence of circulating antigen in the blood be deter- 

 mined either by titration of its complement 1 or by antitryptic 

 index, 2 and finally that the serum containing the circulating 

 antigen be properly preserved and injected into patients between 

 the anaphylactic attacks. The time of injections will be deter- 

 mined by antitryptic index, as the animal experiments have shown 

 that such injections give best results at the time when antitryptic 

 index is lowest. 



Abstracts of the Communications, Pacific Coast Branch. 

 Fifteenth meeting. 



San Francisco, California, December 6, iqi6. 

 40 (1218) 



Note on a toxic nucleoprotein obtained from rat carcinoma. 



By Theodore C. Burnett. 



[From the Rudolph Spreckels Physiological Laboratory of the Uni- 

 versity of California.] 



Flexner-Jobling rat carcinomata of the strain used by Robert- 

 son and the author 3 were ground in a mortar with sand, extracted 

 with M/6 NaCl solution, filtered and centrifuged to remove all 

 foreign particles. The supernatant fluid was poured off, diluted 

 with ten times its volume of NaCl solution, and C0 2 allowed to 

 bubble through it for half an hour. A flocculent precipitate which 

 settled in a few hours was the result. Phenol was added to make 

 the suspension 0.5 per cent. 



The original problem was to ascertain if such a substance, 

 assumed to be cell globulin, would prove to be specific, using com- 

 plement fixation as a test. An attempt was made to immunize 

 a rabbit by intravenous injection, but the rabbit died within five 



1 Bronfenbrenner and Schlesinger, in press, these Proceedings. 



2 Bronfenbrenner, Proc. Soc. Exper. Biol, and Med., 1915, xiii., p. 42. 



3 Robertson and Burnett, Jour. Exper. Med., Vol. 21, 1915, p. 281. 



