The  source  of  the  plug  must  be  somewhere  between  the  lungs  and  the
brain — in  the  pulmonary  veins,  the  left  side  of  the  heart,  the  commence-
ment of  the  aorta,  or  the  large  arteries  of  the  neck.  It  is  possible  that
septic  material  may  pass  through  the  lungs,  and  lodge  in  the  brain,  but  only
capillaries  can  be  obstructed  by  particles  that  can  pass  through  the  capillaries
of  the  lungs,  and  any  local  softening  of  the  brain  thus  produced  is  usually
purulent,  a  cerebral  abscess  or  minute  points  of  suppuration.  When  an
artery  has  been  plugged  in  consequence  of  septicemic  processes  in  the

*This  is  the  common  opinion,  and  is  very  likely  correct,  although  the  evidence  is  not  con-
clusive. In  the  post- mortem  room  hemorrhage  is  the  more  frequent  lesion,  but  hemorrhage
is  more  often  quickly  fatal  than  softening  is.  It  is  probable  that  post-mortems  in  work-
houses would  show  the  cases  of  softening  to  be  in  considerable  excess.
