PROTECTIVE INOCULATIONS. 293 



action but are from ten to twenty times less potent. Similar toxic 

 products were obtained by Pfeiffer from cultures of the Finkler-Prior 

 spirillum and from Spirillum Metchnikovi. 



Sclioll (1890) took advantage of the fact, previously demonstrated 

 by Hueppe, that cultures of the cholera spirillum in egg albumen, in 

 the absence of oxygen, are more toxic than ordinary bouillon cultures. 

 Cultures were made by Hueppe's method in hen's eggs. No poison- 

 ous ptomaines were found, but two toxic albuminous substances were 

 obtained. The albuminous liquid from the egg cultures was dropped 

 into ten times its volume of absolute alcohol, which caused a white 

 precipitate, a portion of which sank to the bottom while another por- 

 tion floated on the surface. The portion which floated was easily 

 dissolved in a very dilute solution of potash and could be precipitated 

 from this solution by the careful addition of acetic acid, but dissolved 

 in an excess of this acid. It dissolved also in a seven-per-cent salt 

 solution, but was precipitated by a saturated solution. It gave the 

 biuret and xanthoprotein reaction. This substance proved to be very 

 poisonous. It killed guinea-pigs within twenty minutes when a few 

 cubic centimetres of the alkaline solution potash were injected into 

 the cavity of the abdomen. Scholl calls this substance cholera-toxo- 

 globulin. The precipitate which fell to the bottom of the receptacle 

 w r as washed with alcohol, then digested with water for twenty minutes 

 at 40 C. Very little was apparently dissolved out by this procedure, 

 but this little proved to be very toxic. In from one to three minutes 

 after the injection of a few cubic centimetres of the solution into the 

 peritoneal cavity of a guinea-pig the animal died. This aqueous 

 solution gave the biuret and xanthoprotein reaction ; it was precipi- 

 tated by mercuric chlorid, nitrate of mercury, and tannin, but not by 

 a saturated solution of ammonium sulphate or acetic acid. This sub- 

 stance Scholl calls cholera-toxo-pepton. The toxic action of these 

 substances is destroyed by a temperature of 100 C., maintained for 

 half an hour, or by 40 to 45 C., maintained for twenty -four hours. 

 But at ordinary temperatures they retain their toxic action for several 

 weeks. 



Gruber (1892) has also obtained a toxic albuminous precipitate by 

 allowing egg cultures to fall into alcohol, drying the precipitate, and 

 then extracting it with water. 



Gamaleia (1893) has obtained a toxin which produces the typical 

 phenomena of cholera, which, according to him, is closely associated 

 with the bacteria cells, but can be extracted by a soda solution or 

 by heating to 55 to 60 C. The conclusion is reached that it is a 

 nucleo-alburnm analogous to the toxalbumins of tetanus and of 



