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. 
Scholl (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 
was 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 isa 
nucleo-albumin analogous to the toxalbumins of tetanus and of 
