Struggling  may  be  prevented  to  some  extent  by  giving  the
ansBsthetic  well  dilnted  with  air  at  the  outset.  Asphyxia
results  also  from  tetanic  fixation,  or  relaxation  of  the  res-
piratory mascles.  The  signs  of  asphyxia  include  cyanotic
mucous  membranes,  muscular  twitchiuga,  shallow,  feeble,
slow  and  irregular  breathing,  with  long  intervals  between
the  respiratory  movements,  and  dilation  of  the  pupils.  If
death  occurs,  the  heart  contiuues  to  beat  after  the  breath-
ing stops.  The  condition  of  the  diaphragm  during  etheriza-
tion is  an  important  guide.  At  first  the  contractions  of  the
diaphragm  are  so  vigorous  that  the  viscera  are  forced
back  (vard,  and  the  abdominal  wall  bulges  outward  during
inspiration.  As  the  inhalation  is  prolonged  the  diaphragm
becomes  fiaccid  and  powerless,  the  respiratory  movements
are  shallow,  and  the  breathing  thoracic.  The  abdominzil
oonteuts  may  then  be  drawn  forward  during  inspiration
into  the  thoracic  cavity,  so  that  the  abdomen  is  retracted
(Hare).  When  the  latter  condition  is  seen,  etherization
should  be  stopped  instantly.
Heart  failure  occurs  more  frequently  with  chloroform,
but  does  occasionally  result  from  the  action  of  ether  upon
animals  with  a  fatty  or  otherwise  weak  heart.  Cardiac
depression  is  shown  by  a  weak,  irregular  and  rapid  pulse,
and  pallor  of  the  mucous  membranes.  The  re.spiratory
movements  are  sustained  after  the  heart  ceases  to  beat  in
fatal  cases.  Operations  should  never  be  done  under
chloroform  before  the  patient  is  fully  under  the  influence
of  the  au£e.Hthetic,  as  irritation  of  a  sensory  nerve  caused
by  even  a  slight  surgical  procedure  may  cause  death  by
reflexly  stimulating  the  vagus  and  inhibiting  the  heart.
