This  for  an  ordinary  man  would  be  1*4  to  2*1  grammes.  Beyond  this
it  is  poisonous,  and  death  occurs  in  tw^enty-four  hours.  Potassium
iodide  has  an  injurious  action  on  the  heart."  *  The  importance  of  these
results  is  shown  by  the  consideration  that  disinfectants  externally
applied  cannot  arrest  the  progress  of  disease  germs  already  established
in  the  body,  since,  as  Koch  says,  "  before  they  destroy  the  parasite,
they  kill  the  host."  The  choice  lies  between  real  though  dangerous
disinfectants  like  chlorine,  and  antiseptics  like  carbolic  acid  which
require  to  be  of  such  strength  as  to  be  expensive  and  almost  inapplic-
able. Prophylactic  treatment,  like  injection,  or  Pasteur's  and  Koch's
inoculation,  would  have  to  supplement  effective  disinfection  externally.
Koch  states  that  to  check  Bacillus  anthracis  in  man,  by  internal  treat-
ment, 1 2  grammes  of  iodine  must  be  constantly  in  circulation.
