]\IE.  J.  LISTEE  ON  THE  EAELT  STAGES  OE  INELAMMATION. 
667 
nervous  system  into  a state  of  muscular  relaxation,  instead  of  the  contraction  which  is 
induced  by  a more  gentle  application  of  the  same  stimulus. 
To  retm-n  to  the  consideration  of  inflammatory  congestion.  Further  light  was  thrown 
upon  the  condition  of  the  blood  in  the  vessels  of  an  irritated  part  by  a series  of  observa- 
tions made  when  the  circulation  had  been  arrested  by  amputation  of  the  limb,  or  by  a 
ligature  round  the  thigh.  This  field  of  inquiry  was  unexpectedly  opened  during  the 
com’se  of  an  experiment  made  with  a view  to  ascertaining  the  effects  produced  by  an 
irritant  upon  the  pigmentary  system  independently  of  the  circulation,  as  will  be 
described  in  the  next  section.  On  the  13th  of  October  1856,  a frog  having  been  killed 
by  destruction  of  the  brain,  the  soft  parts  of  one  of  the  thighs  were  divided  to  the  bone, 
and  a small  piece  of  mustard  was  placed  on  one  of  the  webs  of  that  foot.  An  hour 
afterwards,  on  removing  the  mustard,  1 saw  to  my  great  surprise  that  the  small  area  on 
which  it  had  lain  was  red  to  the  naked  eye,  and  that  its  capillaries,  examined  microsco- 
pically, contained  abundance  of  closely-packed  corpuscles,  while  in  surrounding  parts 
the  blood  was  in  the  same  condition  as  before  the  experiment,  viz.  of  pretty  healthy 
aspect.  In  other  words,  well-marked  inflammatory  congestion  had  been  produced  by 
the  mustard,  and  I afterwards  found  that  the  same  thing  occurred  in  a limb  completely 
severed  from  the  body^. 
This  fact  of  course  completely  eliminated  variations  in  the  calibre  of  the  vessels  and 
consequent  changes  in  the  circulation  from  among  the  causes  of  congestion,  and  demon- 
strated conclusively  its  independence  of  the  central  organs  of  the  nervous  system. 
Further,  it  presented  a very  good  opportunity  for  studying  the  state  of  the  blood  in 
healthy  and  inflamed  parts,  unaccompanied  by  the  effects  of  rapid  movement.  In  sub- 
sequent similar  experiments,  it  was  found  that  the  corpuscles  were  not  brought  to  the 
irritated  area  by  anything  that  indicated  a mutual  attraction  between  the  former  and 
the  latter,  but  were  simply  carried  along  by  slight  accidental  movements  of  the  blood, 
such  as  are  caused  hj  ])Ost-mortem  contractions  of  the  arteries,  and  instead  of  moving 
with  facility,  as  in  other  parts,  stuck  when  they  arrived  in  the  vessels  of  the  area,  in 
consequence  of  undue  adhesiveness.  The  accumulation  of  the  corpuscles  was  never  to 
such  an  extent  as  in  cases  in  which  the  heart  was  driving  the  blood  through  the  part, 
but  it  affected  the  arterial  and  venous  branches  as  well  as  the  capillaries.  Thus,  if  a 
large  vein  happened  to  run  through  the  spot  upon  which  the  mustard  was  placed,  it 
became  in  time  choked  with  a crimson  mass  of  coi’puscles  in  that  part  of  its  extent 
which  lay  beneath  the  mustard ; but  immediately  beyond,  in  both  directions,  the  blood 
in  it  contained  no  more  than  the  usual  proportion  of  corpuscles,  or  sometimes  consider- 
ably less ; and  these  moved  freely  to  and  fro  when  the  web  was  touched,  whereas  those 
* Mr.  Paget,  to  whom  I mentioned  this  experiment,  has  informed  me  that  the  fact  that  stasis  may  be 
induced  by  application  of  irritant  substances  to  the  frog’s  foot  after  the  arrest  of  the  circulation  by  ligature 
of  the  thigh,  had  been  previously  discovered  by  Dr.  H.  "Webeb  of  Giessen  (Mulleb’s  Archiv,  1852),  and 
that  ScHULEB  of  Glarus  had  afterwards  ascertained  that  the  same  thing  occurs  in  an  amputated  limb  {vide 
Wurzburg  Verhandlungen,  1854). 
