608 
ME.  .T.  LISTEE  ON  THE  PAETS  OE  THE  NEETOHS  SYSTEM 
that  part  produced  the  same  effect  as  irritation  of  the  sympathetic,  namely,  pallor  uith 
diminished  temperature* * * §.  M.  Schiff  afterwards  ascertained,  that  after  destruction  of 
the  lower  part  of  the  cervical  and  upper  part  of  the  dorsal  region  of  the  cord  in  Bats, 
there  is  an  immediate  dilatation  of  the  small  vessels  of  the  wings  f,  and  Beowv-Sequaed 
had  previously  shown  that  after  transverse  section  of  the  spinal  cord  in  the  lumbar  region 
in  Birds  and  Mammals,  an  increase  of  1°,  2°,  or  -3°  Fahe.  took  place  in  the  temperature  of 
the  paralysed  parts  J.  All  these  facts  tend  to  the  same  conclusion,  namely,  that  the  spinal 
cord  is  the  part  of  the  nervous  centres  which  presides  over  the  blood-vessels,  and  that 
one  important  action  at  least  which  it  induces  in  them  is  constriction  of  the  circular 
coat  of  the  arteries.  But  there  still  remains,  I believe,  some  difference  of  opinion  with 
regard  to  the  interpretation  of  Beenaed’s  experiment ; and  there  might  be  some  colour 
for  the  idea  that  the  red  and  turgid  state  of  the  vessels  seen  after  division  of  the 
sympathetic  in  the  neck  was  due  to  a change  in  the  blood,  such  as  occurs  in  inflamma- 
tion, and  that  the  pallor  ensuing  upon  galvanizing  the  nerve  was  the  result  of  a return 
of  the  vital  fluid  to  its  normal  condition  after  restoration  of  nervous  influence.  But  all 
ambiguity  of  this  kind  seems  to  me  to  be  removed  by  some  observations  made  several 
years  ago  by  Mr.  Whaetox  Jones  upon  the  Frog.  This  animal  is  peculiarly  adapted 
for  investigations  on  this  subject,  because  both  the  calibre  of  the  vessels  and  the  state  of 
the  blood  as  it  flows  through  them  can  be  observed  with  the  utmost  facility  in  the  web ; 
and  Mr.  Jones  found  that  division  of  the  sciatic  nerve  was  followed  by  dilatation  of  the 
arteries,  but  that  this  increase  of  calibre,  so  far  from  being  caused  by  an  obstruction  in 
the  progress  of  the  blood,  was  accompanied  with  unusually  free  and  rapid  flow  through 
the  capillaries  §.  But  with  regard  to  the  part  of  the  nervous  system  which  regulates  the 
contractions  of  the  arteries,  some  more  recent  observations  by  the  same  author  ai’e  at 
variance  with  the  conclusion  above  drawn  from  experiments  by  others  upon  Mammalia. 
For  he  states  that  the  division  of  the  roots  of  the  sciatic  nerve  unthin  the  spmal  canal 
failed  to  produce  dilatation  of  the  vessels ; whence  it  was  inferred  that  the  sympathetic 
fibres  of  the  sciatic  trunk,  as  distinguished  from  those  derived  from  the  cord,  ai-e  the 
channels  through  which  the  stimulus  is  transmitted  to  the  arterial  coats  [f.  Wallee 
and  Budge’s  experiments,  on  the  other  hand,  appear  to  show  that  it  is  from  the  cord  that 
the  sympathetic  derives  its  controlling  power  over  the  arteries.  This  discrepancy  upon 
a matter  of  such  great  importance  in  physiology  appeared  to  me  to  demand  fm-ther 
inquiry^,  and  I propose  in  the  present  paper  to  communicate  the  results  to  which  this 
investigation  has  led. 
* Comptes  Eendus,  vol.  xxxi.  pp.  377,  575. 
t Gazette  Hebdomadaire  de  Med.  et  de  Chir.  1854,  pp.  421,  424. 
:J;  Experimental  Eesearches,  New  York,  1853,  p.  8. 
§ Essay  on  the  State  of  the  Blood  and  the  Blood- vesselsin  Inflammation,  hy  T.  Wharton  Jones,  Esq., 
F.E.S.  Guy’s  Hospital  Eeports,  yoI.  viii.  p.  12. 
II  Observations  on  the  State  of  the  Blood  and  the  Blood-vessels  in  Inflammation,  Med.  and  Chir.  Trans, 
vol.  xxxvi. 
Since  this  paper  was  read,  my  attention  has  been  called  by  Professor  Goodsir  to  experiments  recently 
