656 
ME.  J.  LISTEE  ON  THE  EAELT  STAG-ES  OF  DsFLA^BIATION. 
of  the  body  go  on  then  as  usual,  these  cases  appear  to  prove  absolutely  that  the  forces 
which  are  concerned  in  the  mutual  interchanges  between  the  tissues  and  the  nutrient 
fluid  do  not  cause  any  movement  whatever. 
But  even  supposing  that  it  were  admitted,  for  the  sake  of  argument,  that  the  vital 
aflinities  do,  under  ordinary  circumstances,  cause  some  movement  of  the  blood,  but  lose 
that  power  in  an  animal  under  chloroform,  such  an  admission  would  hardly  affect  the 
discussion  regarding  the  cause  of  stagnation  in  inflammation ; for  in  a frog  fully  under 
the  influence  of  the  anaesthetic,  in  which,  as  we  have  seen,  the  heart  is  the  only  cause 
of  circulation,  all  the  phenomena  that  result  from  initation  of  the  web  take  place  pre- 
cisely in  the  same  manner  as  in  one  to  which  the  narcotic  has  not  been  administered. 
The  fact  that  the  heart,  even  though  much  enfeebled  by  chlorofoim,  is  capable,  rm- 
aided  by  any  other  force,  of  maintaining  the  circulation  for  an  indefinite  period  without 
the  occurrence  of  obstruction  in  the  capillaries,  or  any  undue  accumulation  of  cor- 
puscles in  them,  affords  positive  proof  that  any  other  cause  of  movement  which  may  be 
conceived  to  exist  when  chloroform  has  not  been  given,  must  be  altogether  insignificant, 
and  that  the  cessation  of  its  operation  does  not  give  rise  to  stagnation  of  the  blood*. 
The  veins  of  the  frog’s  web  afford  very  little  evidence  of  contractihty ; but  a small 
amount  of  unstriped  muscular  tissue,  transversely  arranged,  is  distinctly  to  be  seen  in 
the  larger  venous  branches;  and  on  one  occasion  I observed  a very  considerable  degree 
of  local  contraction,  as  measured  from  the  outer  borders  of  the  external  coat  of  a vein 
running  through  a small  area  which  I had  pinched  forcibly  -with  forceps.  I have  also 
seen  one  expand  on  sudden  dilatation  of  the  arteries  of  the  web,  so  that  its  diameter 
increased  from  twelve  to  fourteen  degrees  of  a micrometer ; but  this  is  perhaps  exph- 
cable  by  elasticity  f. 
It  has  been  already  mentioned  that  the  arteries  undergo  spontaneous  variations  ot 
calibre.  Such  changes  are  constantly  going  on  at  varjing  intervals,  there  being  nothuig 
of  a rhythmical  character  about  them.  A struggle  on  the  part  of  the  animal  is 
* Dr.  Shaepet  has  for  many  years  alluded  in  his  lectimes  to  the  circumstance  that,  the  weaker  the 
animal,  the  more  do  the  effects  of  the  successive  cardiac  impulses  show  tliemselves  in  the  capillaiies  of  the 
webs,  as  evidence  that  the  action  of  the  heart  is  sufficient  to  account  for  the  circulation.  He  also  informs 
me  that  he  has  frequently  verified  the  observation  of  Spallanzani,  that  in  the  gills  of  the  tadpole  the  flow 
of  the  blood  ceases  completely  in  the  intervals  between  the  pidses  produced  by  the  ventricular  contractious. 
t Since  the  reading  of  this  paper  I have  noticed  striking  examples  of  the  contractihty  of  the  larger  veins 
in  the  higher  animals.  Thus,  on  exposing  the  jugular  in  a living  calf,  I have  seen  a pai’ticular  paid  of  the 
vessel  irritated  by  the  process  of  dissection  shrunk  to  about  a third  of  its  previous  cahhre.  In  the  human 
subject,  too,  when  amputating  lately  at  the  shoulder-joint  on  account  of  contusion  inflicted  by  maehiuerv 
upon  a previously  healthy  hmh,  I noticed  the  axillary  vein  reduced  to  about  half  its  natui’al  calibre  at  the 
part  where  it  was  divided,  which  was  in  the  immediate  vicinity  of  the  injury.  I have  also  had  occasion  to 
observe  the  post-mortem  contractions  of  the  subcutaneous  veins  of  the  sheep’s  foot,  which  are  can’ied  to 
such  an  extent  as  to  reduce  the  vessels  from  the  size  of  a crowquil  to  about  that  of  a darning-needle.  The  ; 
minute  veins  also  sometimes  exhibit  great  contractihty  in  the  higher  animals,  as  in  the  nregular  constrictions 
often  seen  in  those  of  the  mesentery  of  the  mouse,  and  in  the  remarkable  rhythmical  valuations  in  calibre  | 
discovered  by  Mr.  Whaeton  Jones  in  those  of  the  bat’s  wing  (Philosophical  Transactions,  1852).  ‘ 
