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ME.  J.  LISTEE  OJ^  THE  EAELY  STAGES  OE  ENTLA^OIATIOX. 
within  the  area  remained  fixed.  This  proved  that  the  cause  of  the  accumulation  of  the 
corpuscles  did  not  reside  specially  in  the  capillaries,  and  also  showed  distinctly  that  it 
could  not  be  explained  by  mere  abnormal  adhesiveness  of  the  vascular  parietes,  which 
was,  I understand,  the  view  entertained  by  the  late  Dr.  ]SLveishall  Hall  ; for  sup- 
posing the  walls  of  the  vessels  to  experience  such  a change,  which  seems  by  no  means 
improbable,  this  could  only  lead  to  encrusting  of  the  lining  membrane  of  such  a vein 
with  adhermg  corpuscles,  and  not  to  the  occupation  of  its  whole  calibre  by  them,  as 
took  place  in  these  cases,  unless  the  corpuscles  were  themselves  also  abnormally  adhe- 
sive. 
Another  important  fact  which  was  brought  out  by  this  class  of  experiments  is,  that 
mere  quiescence  of  the  blood  in  the  vessels  of  a healthy  part  fails  to  induce  aggregation 
of  the  red  corpuscles,  such  as  occurs  in  blood  outside  the  body.  In  the  parts  which 
had  not  been  subjected  to  irritation,  the  corpuscles  exhibited  no  trace  of  adhesiveness; 
and  though  completely  at  rest,  they  were  nowhere  to  be  seen  grouped  together,  surface 
to  surface,  although  in  the  larger  vessels  there  was  abundant  space  for  the  occurrence 
of  this  phenomenon,  which  invariably  presents  itself  in  freshly  drawn  frog’s  blood 
examined  between  plates  of  glass  in  a sufficiently  thick  film.  On  one  occasion,  when 
examining  the  tissues  of  the  web  of  a frog  under  chloroform,  the  limb  being  kept  steady 
by  a string  tied  tightly  round  the  thigh,  so  as  completely  to  arrest  the  cii’culation,  I was 
particularly  struck  with  the  total  absence  of  adhesiveness  in  the  red  coi’puscles ; so  much 
so,  that,  as  the  foot  had  been  kept  moist  without  circulation  for  about  three  hoius,  I 
suspected  that  it  must  have  imbibed  water,  which,  when  mixed  with  blood  outside  the 
body,  destroys  altogether  the  adhesiveness  of  the  red  corpuscles.  This,  however,  proved 
to  be  a mistake ; for,  having  occasion  to  administer  more  chloroform,  I applied  it  on  a 
piece  of  lint  of  considerable  size  without  taking  the  usual  precaution  of  protecting  the 
foot  from  the  vapour,  and  left  it  so  for  about  a quarter  of  an  hour.  On  re-examination 
of  the  web,  the  red  corpuscles  were  found  to  possess  much  mutual  adhesiveness,  and  in 
the  larger  vessels  were  grouped  together  into  masses,  with  considerable  spaces  of  clear 
liquor  sanguinis,  just  as  in  the  best-marked  forms  of  aggregation  in  fi-og’s  blood  outside 
the  body.  One  of  these  masses  was  drawn  by  camera  lucida,  and  is  represented  in  the 
sketch  at  page  648,  along  with  the  outline  of  the  vessel  in  which  it  lay.  I afteiAvards 
purposely  induced  a similar  change  in  the  blood  mthin  the  vessels  of  an  amputated 
limb  by  means  of  mustard*.  Having  ascertained  that  the  red  corpuscles,  though  they 
had  been  long  at  rest,  were  perfectly  free  from  the  slightest  tendency  to  aggregation, 
I suspended,  at  a little  distance  from  the  web,  a piece  of  lint  smeared  ufith  fleshly  pre- 
pared mustard,  so  that  the  pungent  vapour  of  the  volatile  oil  might  play  upon  it ; and 
left  it  so  for  about  a quarter  of  an  hour,  when  I found  the  red  discs  aggregated,  as 
usually  seen  in  frog’s  blood  outside  the  body.  I then  shed  some  blood  from  the  other 
leg  between  two  plates  of  glass,  and  on  carefully  sketching  and  comparing  the  groups  of 
corpuscles  in  this  specimen  and  those  within  the  vessels  of  the  iiiitated  webs,  found  that 
* This  experiment  was  performed  subsequently  to  the  reading  of  the  paper. 
