ME.  J.  LISTEE  ON  THE  EAELT  STAG-ES  OF  INFLAMMATION. 
G99 
are  further  corroborated  by  the  immediate  transition  which  is  apt  to  occur  from  intense 
human  inflammation  to  gangrene*. 
But  a comprehensive  and  complete  accoimt  of  the  inflammatory  process  must  embrace 
not  merely  the  state  to  which  the  tissues  are  brought  when  the  disease  is  fairly  established, 
but  also  the  causes  which  lead  to  it. 
Inflammation  is  sometimes  brought  about  in  man  in  a way  strictly  analogous  to  that 
in  which  we  induce  it  in  the  web  of  the  frog’s  foot,  viz.  by  the  immediate  operation  of 
some  noxious  agent  from  without,  as  when  boiling  water  is  poured  upon  the  skin.  One 
pecuharity  connected  vdth  such  cases,  as  compared  with  those  which  are  of  idiopathic 
origin,  is  the  great  rapidity  with  which  the  various  stages  of  the  disorder  are  often  deve- 
loped. This,  however,  is  the  natural  consequence  of  the  direct  manner  in  which  the 
prejudicial  influence  is  exerted  upon  the  tissues;  the  inflammatory  phenomena  super- 
vening more  speedily  in  proportion  to  the  energy  of  the  irritant.  This  principle  is  well 
illustrated  by  the  effects  of  mechanical  violence  upon  the  human  integument.  A mode- 
rate degree  of  pressure  applied  continuously  gives  rise,  during  the  first  few  hours,  to 
nothing  more  than  inflammatory  congestion,  which  disappears  soon  after  the  pressure 
has  been  removed,  as  seen  in  the  red  mark  produced  upon  the  forehead  by  a tightly- 
fitting  hat.  But  if  such  treatment  be  continued  for  a considerably  longer  period,  vesica- 
tion will  result,  as  when  apparatus  employed  for  the  treatment  of  fractures  is  applied 
too  firmly  for  many  hours  together  over  a bony  prominence.  The  same  effect  which  is 
thus  slowly  developed  under  a moderate  degree  of  mechanical  irritation,  may,  however, 
be  induced  very  rapidly  through  the  same  agency  in  a more  intense  form,  as  is  shown  by 
the  bullae  which  are  often  observed  in  surgical  practice  very  soon  after  the  infliction  of 
a severe  contusion.  Here  the  source  of  irritation  being  no  longer  in  operation,  there  is 
no  blush  of  redness  in  the  vicinity  dependent  upon  arterial  dilatation,  and  hence  such 
cases  are  often  supposed  to  have  nothing  in  common  with  inflammation ; and  I have 
known  these  vesicles  mistaken  for  evidence  of  gangrene,  so  as  to  lead  to  unnecessary 
amputation.  The  suddenness  with  which  inflammatory  oedema  arises  in  consequence  of 
the  bites  or  stings  of  venomous  reptiles  is  explicable  on  the  same  principle.  The  poison 
appears  to  diffuse  itself  among  the  tissues  so  as  to  operate  directly  upon  them,  and  when 
extremely  vfrulent,  kills  them  outright ; but  Avhen  less  potent,  produces  merely  a tempo- 
rai-y  though  rapid  prostration  of  their  vital  energies  with  consequent  inflammatory 
effusion.  Again,  the  congestion  of  the  lungs,  which  comes  on  so  quickly  in  asphyxia, 
has  been  before  alluded  tof,  as  probably  the  result  of  the  sedative  influence  which,  from 
experiments  upon  the  frog,  we  are  led  to  believe  must  be  produced  upon  the  pulmonary 
tissue  by  the  abnormal  amount  of  carbonic  acid  in  the  air-cells. 
In  the  class  of  cases  hitherto  considered,  the  derangement  of  the  part,  and  the  causes 
which  lead  to  it,  being  both,  to  a considerable  extent,  understood,  the  disease  may,  I 
think,  be  regarded  as  in  so  far  satisfactorily  explained.  But  one  important  lesson  taught 
* The  degenerations  of  tissue  which  result  from  inflammation,  ably  delineated  by  Mr.  Paget  in  his 
‘ Lectures  on  Surgical  Pathology,’  are  additional  evidence  in  the  same  direction. 
t See  page  687. 
