688 
ME.  J.  LISTEE  ON  THE  EAELT  STAGES  OE  INFLAMMATION. 
cess  of  concentration  had  advanced  considerably  in  the  next  web,  but  in  that  on  which 
the  galvanism  had  acted  had  only  just  commenced,  even  in  the  parts  most  remote  from 
the  point  to  which  the  poles  of  the  battery  were  applied ; while  in  the  vicinity  of  that 
spot  the  state  of  full  diffasion  still  continued.  After  the  lapse  of  three  more  hours,  how- 
ever, the  pigment  was  almost  fully  concentrated  in  the  part  of  the  web  where  it  was 
before  only  slightly  so ; and  even  where  it  had  been  most  directly  subjected  to  the  gal- 
vanic influence,  it  had  undergone  a certain,  though  very  slight  degree  of  the  same  change, 
the  chromatophorous  cells  having  even  there  partially  recovered  their  functions. 
This  inherent  power  in  the  tissues  of  recovering  from  the  effects  of  initation,  explains 
the  occurrence  of  resolution  in  an  amputated  limb,  such  as  I once  obseiwed  in  a case 
where  a moderate  amount  of  congestion  had  been  induced  under  the  action  of  oil  of  tur- 
pentine before  the  animal  was  killed,  and  the  blood  resumed  to  a great  extent  its  normal 
characters  in  the  vessels  several  hours  after  the  limb  had  been  severed  from  the  body. 
The  return  of  the  blood  along  with  the  tissues  to  the  state  of  health  is  a very  inter- 
esting circumstance.  Whether  it  depends  upon  an  intrinsic  power  of  recovery  on  the 
part  of  the  vital  fluid,  or  on  the  living  solids  resuming  an  active  operation  upon  it,  is  at 
preseirt  uncertain ; but  in  the  mean  time,  the  phenomena  of  resolution  already  assume 
a far  more  intelligible  aspect  than  heretofore,  on  the  hypothesis  that  the  tissues  gene- 
rally are  endowed  wdth  the  same  faculty  of  self-restoration  as  the  pigment-cells. 
It  may  be  well  to  give  here  a list  of  all  the  agents  whose  effects  upon  the  pigmentary 
functions  I have  investigated.  They  are  as  follow : — Mechanical  -violence,  the  galvanic 
shock,  desiccation  of  the  tissues*,  dry  heat,  warm  water  at  100°  Fahk.,  intense  cold, 
caustic  ammonia,  a strong  solution  of  common  salt,  carbonic  acid,  acetic  acid,  tincture 
of  iodine,  chloroform,  oil  of  turpentine,  mustard,  tinctm’e  of  cantharides,  and  croton  oil. 
These  are  all  of  them  irritants,  ^.  e.  give  rise  to  inflammatory  congestion  thr’ough  their 
direct  action  upon  a vascular  part,  as  I have  witnessed  in  the  frog’s  web  in  every  case 
except  that  of  cold,  the  influence  of  which  in  causing  intense  inflammation  in  the  human 
subject  is,  however,  familiar  to  all  f . All  of  them  also  afforded,  in  their  effects  irpon  the 
pigment-cells,  ocular  evidence  of  impairment  of  the  functional  actmty  of  the  tissues  on 
which  they  act ; and  considering  the  number  included  in  the  list,  and  their’  great  variety 
in  essential  nature,  we  need  not  hesitate  to  admit  that  similar  effects  are  produced  by 
the  entire  class  of  irritants. 
There  is  another  tissue  in  the  frog’s  web  which  discharges  functiorrs  apparerrt  to  the 
eye,  viz.  the  arterial  muscular  fibre-cells,  the  contractions  of  which  are  readily  recog- 
* The  effects  of  deficiency  of  moisture  in  the  web  were  observed  in  amputated  limbs,  in  which  I liave 
seen  both  suspension  of  pigmentary  functions  from  this  cause  and  recovery  from  that  state  after  the  appli- 
cation of  water.  WhUe  the  circulation  is  going  on  in  the  living  animal  I have  not  foimd  desiccation  of  the 
web  to  occur,  unless  the  tissues  had  been  weakened  more  or  less  by  irritation. 
t The  only  experiment  which  I made  with  cold  was  performed  by  introducing  a test-tube,  containing  a 
dark  amputated  limb,  into  a freezing  mixture  of  ice  and  salt  at  about  20°  Eahr.  for  ten  minutes.  When 
the  frozen  limb  had  thawed,  I ascertained,  on  microscopic  examination,  that  the  pigment  had  undergone  a 
slight  degree  oi post  mortem  concentration,  but  five  hours  later  it  was  still  in  much  the  same  condition. 
