ME.  J.  LISTEE  ON  THE  EAELY  STAGES  OF  INFLAMMATION. 
685 
cells  possess  a local  nervous  apparatus,  on  which  the  occurrence  and  maintenance  oipost 
m(yrtmh  concentration  depend,  and  the  paralysis  of  which,  while  the  pigment-cells  retain 
their  powers,  would  give  rise  to  diffusion  in  an  amputated  limb.  Be  this  as  it  may,  the 
fact  that  the  state  of  full  diffusion  continued  in  the  ring  around  the  congested  area  in 
the  last  mustard  experiment  for  hours  after  the  irritant  had  been  removed,  although, 
during  that  time,  complete  concentration  occurred  in  the  web  generally,  is  pretty  clear 
evidence  that  the  pigment-cells  in  that  part  had  not  merely  been  stimulated  to  increased 
action  (for  in  that  case  they  would  have  returned  to  their  former  condition  soon  after 
the  stimulus  had  ceased  to  operate),  but  had  suffered  a loss  of  the  faculty  of  concentra- 
tion. Whether  the  loss  of  power  resided  in  the  nerves  of  the  pigment-cells,  or  in  those 
cells  theinselves,  is  a matter  of  indifference  as  regards  the  objects  of  the  present  inquiry ; 
the  important  fact  being  that  an  action  of  the  mustard  so  mild  as  to  give  rise  to  little 
or  no  derangement  of  the  blood,  nevertheless  produced  a certain  degree  of  loss  of  power 
in  the  part  on  which  it  operated.  There  can  be  no  doubt  that  the  same  principles  apply 
to  the  cases  of  croton  oil  and  cantharides ; and  thus  the  diffusion  caused  by  these  three 
irritants  assumes  a high  interest,  as  visible  evidence  of  diminished  functional  activity 
accompanying,  if  not  preceding,  the  earliest  approaches  to  inflammatory  congestion  in 
parts  which  have  been  subjected  to  their  influence. 
With  the  view  of  ascertaining  the  nature  of  the  effect  produced  on  the  pigment-cells 
by  the  mildest  action  of  chloroform  which  is  capable  of  causing  inflammatory  disorder, 
I ascertained,  by  repeated  experiments,  the  shortest  time  in  which  the  vapour  of  that 
hquid  gave  rise  to  unequivocal  signs  of  a congestive  tendency  in  the  web  of  the  living 
frog ; and  having  found  this  to  be  about  half  a minute,  suspended  one  of  the  legs  of  a 
recently  killed  dark  frog  in  a vessel,  the  bottom  of  which  was  covered  with  chloroform, 
having  previously  examined  the  webs  microscopically,  and  found  that  full  diffusion  of 
pigment  existed  throughout  them.  The  result  was  that  the  limb  exposed  to  the  chloro- 
form vapour  remained  dark,  while  the  other  became  gradually  pale.  On  re-examina- 
tion of  the  former  after  some  hours,  each  web  presented  stripes  of  full  diffusion  of  pig- 
ment alternating  with  others  in  a medium  condition;  their  direction  being  at  right 
angles  to  the  margin  of  the  web.  The  longitudinal  folds  in  which  the  webs  had  hap- 
pened to  be,  had  prevented  the  chloroform  vapour  from  gaining  equally  free  access  to 
all  parts ; yet  the  chromatophorous  cells  in  the  stripes  that  had  been  thus  partially 
protected  from  its  influence  had  been  incapable  of  complete  concentration,  showing  that 
even  the  exceedingly  slight  degree  of  action  which  the  chloroform  could  have  exerted 
upon  these  places  sufficed  to  diminish,  though  not  to  destroy,  the  functional  activity  of 
the  pigmentary  tissue. 
In  one  of  the  experiments  performed  in  order  to  determine  the  effect  of  mechanical 
violence,  as  before  alluded  to,  the  pigment  remained  unchanged  for  days  in  the  area 
which  had  been  pinched,  while  varying  in  other  parts  of  the  web ; yet,  though  great 
excess  of  red  corpuscles  existed  in  the  vessels  of  the  affected  spot,  they  never  ceased  to 
move ; showing  that  the  functions  of  the  pigment-cells  might  be  completely  suspended 
by  a degree  of  irritation  short  of  that  which  occasions  actual  stagnation  of  the  blood. 
