ME.  J.  LISTEE  ON  THE  EAELT  STAG-ES  OF  INFLAMMATION. 
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closure,  generally  lasting  for  several  seconds'^,  and  then  giving  place  to  dilatation 
beyond  their  original  dimensions,  to  which  they  afterwards  gradually  returned.  The 
dilatation  differed  in  different  instances,  being  generally  more  decided  and  more  perma- 
nent, when  the  water  was  hotter  and  longer  applied  f.  In  one  case,  water  at  100° 
thrown  upon  the  web  for  a brief  period  caused  constriction  for  a few  seconds  in  the 
artery  under  observation,  followed  by  dilatation.  While  the  vessels  were  still  above 
their  usual  calibre,  more  water  of  the  same  temperature  was  applied  as  before,  and 
again  induced  contraction  followed  by  abnormal  dilatation,  which  was  again  made  to 
give  place  to  constriction  by  a third  similar  application : the  experiments  were  repeated 
within  a few  seconds  of  each  other. 
When  water  not  higher  in  temperatm’e  than  from  110°  to  140°  was  thrown  for  not 
longer  than  a second  or  two  upon  a perfectly  healthy  web,  the  changes  above  described 
in  the  diameter  of  the  arteries  produced  effects  upon  the  flow  of  blood  through  the 
capillaries,  precisely  similar  to  those  mentioned  at  the  conclusion  of  the  last  section. 
Thus  in  one  such  case  the  constriction  of  an  artery  lasted  for  several  seconds,  and  was 
in  the  first  instance  so  tight  as  to  prevent  any  flow  in  the  field  of  capillaries  supplied  by 
it;  then  relaxing  slightly,  it  allowed  single  corpuscles  to  pass  along  it  with  great 
difficulty,  so  that  the  blood  became  almost  entirely  filtered  of  its  particles,  and  at  the  same 
time  the  force  of  the  heart  being  to  a great  extent  taken  off  from  the  elastic  capillaries, 
hquor  sanguinis  almost  destitute  of  corpuscles  flowed  in  slow  pulsating  streams  along 
the  veins:  finally,  the  dilatation  becoming  complete,  blood  of  ordinary  appearance 
rushed  through  with  great  rapidity. 
If,  however,  such  experiments  had  been  several  times  repeated  upon  the  same  foot,  and 
more  especially  if  the  warm  water  had  acted  for  longer  periods,  another  class  of  symptoms 
began  to  show  themselves ; the  corpuscles  passing  on  less  freely  than  the  liquor  sanguinis 
through  the  capillaries,  and  lagging  behind  so  as  to  accumulate  in  abnormal  proportion 
to  the  plasma,  and  stagnating  completely  when  the  force  of  the  heart  was  partially  taken  off 
through  contraction  of  the  arteries,  though  passing  on  again  when  the  vessels  dilated  J. 
* The  period  of  constrictiou  varied  much  in  different  instances,  and  it  sometimes  passed  off  (if  it  occnrred 
at  aU)  before  it  could  be  observed.  It  was  best  marked  in  a case,  in  which,  the  animal  being  very  qniet, 
chloroform  was  not  employed,  The  anaesthetic  appears  to  impair  the  fimctions  of  the  spinal  cord  as  a 
regulator  of  the  calibre  of  the  vessels  ; and  its  administration  is  generally  followed  by  their  dilatation. 
t Water  of  the  temperature  of  the  room  applied  in  the  same  way  after  warm  water  had  been  several 
times  employed,  caused  complete  constriction  of  the  arteries,  lasting  for  several  seconds  ; but  the  subsequent 
dilatation  was  very  little  if  at  all  beyond  the  normal  calibre. 
X This  effect  of  arterial  contraction  in  producing  accumnlation  and  stagnation  of  corpnscles  in  the  capil- 
laries has  been  described  by  Mr.  Whabton  Jones  as  occurring  in  a state  of  health  (vide  Guy’s  Hospital 
Eeports,  he.  cit.).  The  reason  of  this  I believe  to  have  been,  that  mnch  greater  care  than  is  generally 
supposed  is  required  in  order  to  avoid  any  irritation  whatever  of  the  delicate  webs.  The  viciuity  of  the 
warm  hand  is  particularly  apt  to  produce  this  effect ; and  I have  known  it,  when  continned  for  a quarter  of 
an  hour,  cause  complete  stagnation  of  the  blood  throughout  the  webs,  while  a very  much  shorter  period  is 
sufficient  to  induce  a decidedly  abnormal  condition.  I have  myself  only  become  fully  aware  of  the  great 
susceptibility  of  the  foot  of  the  frog  to  injury  from  warmth  since  the  reading  of  this  paper.  An  nnhealthy 
