690 
MR.  J.  LISTEE  ON  THE  EAELT  STAGES  OE  INTXAADIATION. 
the  point  of  a needle  firmly  across  the  vessel  failed  to  induce  the  slightest  contraction  in 
it,  even  at  the  very  point  crossed  by  the  needle ; proving  that  the  muscular  fibre-cells 
had  lost  their  irritability.  At  the  same  time  it  is  by  no  means  improbable  that  the 
nerves  of  the  arteries  may  suffer  before  their  muscular  constituents,  just  as  in  the  intes- 
tines, after  death,  the  functions  of  the  intrinsic  nen^ous  apparatus  are  lost  some  time 
before  muscular  contractility  ceases*. 
The  question  whether  the  suspension  of  function  induced  by  irritants  is  confined  to 
the  nerves  or  affects  the  tissues  generally,  being  one  of  great  interest,  I was  anxious  to 
obtain  clear  evidence  regarding  it ; and  it  occurred  to  me  that  valuable  inforaaation 
would  probably  be  derived  from  observing  the  effects  of  such  agents  upon  the  action  of 
the  cilia,  which,  though  not  present  in  the  web  of  the  &og,  exist  in  abundance  upon  the 
mucous  surfaces  of  the  mouth  and  oesophagus  of  that  animal.  Dr.  Sharpet,  in  his  cele- 
brated article  “ Cilia”  in  the  ‘ Cyclopsedia  of  Anatomy  and  Physiology,’  mentions  experi- 
ments made  by  Puekinje  and  Valentin,  and  also  by  himself,  with  a gi-eat  variety  of 
substances,  including  among  the  rest  some  irritants,  which,  when  apphed  with  sufficient 
energy,  arrested  completely,  by  their  chemical  action  as  it  was  supposed,  the  movements 
of  the  lashing  filaments.  It  is  evident,  however,  that  in  order  to  produce  effects  at  all 
comparable  to  the  state  of  the  tissues  of  the  frog’s  web  in  congestion,  it  would  be  neces- 
sary to  adopt  some  more  delicate  method  of  experimenting,  and  the  most  eligible  means 
for  this  purpose  seemed  to  be  to  allow  an  irritating  vapour  to  play  upon  a ciliated  sur- 
face. Accordingly,  on  the  30th  of  November,  1857f,  ha’ving  cut  off  a small  piece  of 
the  tongue  of  a frog  killed  about  an  hour  before,  and  placed  it  upon  a slip  of  glass 
under  the  microscope,  with  just  enough  water  to  permit  the  free  play  of  the  cilia,  I held 
near  to  it  a piece  of  lint  soaked  in  chloroform,  keeping  my  eye  over  the  microscope. 
The  effect  was  instantaneous  cessation  of  the  previously  rapid  action  of  the  cilia,  which 
now  stood  out  straight  and  motionless,  like  the  hairs  of  a brush.  I now  immediately 
withdrew  the  lint,  after  which  the  same  state  of  complete  inaction  continued  for  about 
half  a minute,  when  languid  movements  began  to  show  themselves,  and  after  the  lapse 
of  five  minutes  more  the  ciliary  action  was  going  on  pretty  briskly  in  some  parts,  and 
ten  minutes  later  seemed  to  have  almost  completely  recovered. 
Thus  chloroform  vapour  produced  in  the  ciliated  epithelium-cells  a condition  precisely 
similar  to  that  brought  about  in  the  pigment-cells  by  irritants  applied  so  as  to  cause 
inflammatory  congestion  of  the  web,  viz.  a state  of  suspension  or  temporary  deprivation 
of  functional  activity.  And  as  the  removal  of  the  epithelium-cells  fi-om  the  smTace  on 
which  they  grow  does  not  arrest  the  movements  of  their  cilia,  no  mere  paralysis  of  nerves 
lying  beneath,  still  contained  blood  of  natural  appearance,  and  showed  evidence  of  languid  contractiUty, 
whde  in  the  capillaries  of  the  plantar  layer  of  the  web,  the  circulation  was  still  going  on  in  a prettj'  healthy 
state.  This  frog,  however,  seemed  endowed  with  unusual  powers  of  vitality  in  the  tissues.  This  observa- 
tion, as  well  as  that  in  the  text  to  which  this  note  refers,  v'as  made  subsequently  to  the  reading  of  the  paper. 
* See  the  paper  ‘ On  the  Functions  of  the  Visceral  Nerves,’  before  referred  to. 
f This  date  indicates  that  the  experiments  on  the  ciHa  have  been  performed  since  the  paper  was  read. 
