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  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  194 
  3 
  

  

  striking 
  distance. 
  None 
  of 
  our 
  North 
  American 
  pit 
  vipers 
  actually 
  

   jumps 
  off 
  the 
  ground 
  in 
  making 
  an 
  attack. 
  As 
  the 
  head 
  is 
  thrown 
  

   forward 
  for 
  the 
  blow, 
  the 
  mouth 
  is 
  opened, 
  and 
  the 
  fangs, 
  which 
  are 
  

   attached 
  solidly 
  to 
  the 
  movable 
  maxilla, 
  are 
  brought 
  into 
  striking 
  

   position 
  as 
  shown 
  in 
  figure 
  1. 
  The 
  venom 
  is 
  contained 
  in 
  a 
  large 
  

   specialized 
  salivary 
  gland 
  near 
  the 
  angle 
  of 
  the 
  jaw 
  (its 
  presence 
  is 
  the 
  

   cause 
  of 
  the 
  conspicuous 
  triangular 
  widening 
  of 
  the 
  snake's 
  head 
  pos- 
  

   teriorly), 
  and 
  this 
  venom 
  runs 
  forward 
  through 
  a 
  tube 
  connecting 
  

   with 
  the 
  hollow 
  fang 
  in 
  the 
  upper 
  jaw. 
  The 
  comparison 
  to 
  a 
  hypo- 
  

   dermic 
  needle 
  is 
  very 
  appropriate. 
  When 
  the 
  snake's 
  fangs 
  strike 
  

   the 
  victim's 
  flesh, 
  the 
  weight 
  of 
  its 
  body 
  drives 
  them 
  deep, 
  and 
  they 
  

   leave 
  their 
  load 
  of 
  venom 
  or 
  are 
  sometimes 
  broken 
  off 
  and 
  stay 
  in 
  

   the 
  wound. 
  The 
  loss 
  of 
  its 
  functional 
  fangs 
  does 
  not 
  long 
  incon- 
  

   venience 
  the 
  pit 
  viper, 
  however. 
  There 
  is 
  a 
  series 
  of 
  developing 
  teeth 
  

   at 
  the 
  base 
  of 
  each 
  fang, 
  and 
  whenever 
  a 
  fang 
  is 
  shed 
  or 
  breaks 
  off, 
  

   a 
  new 
  one 
  comes 
  forward 
  to 
  take 
  its 
  place 
  in 
  a 
  few 
  days. 
  To 
  render 
  

   a 
  pit 
  viper 
  "harmless" 
  by 
  removing 
  all 
  these 
  fangs 
  thoroughly 
  would 
  

   necessitate 
  cutting 
  into 
  the 
  upper 
  jaw 
  so 
  deeply 
  that 
  the 
  snake 
  would 
  

   probably 
  die. 
  Every 
  pit 
  viper 
  has 
  also 
  some 
  solid 
  teeth 
  with 
  which 
  

   to 
  hold 
  the 
  prey 
  and 
  prevent 
  it 
  from 
  wriggling 
  away 
  while 
  the 
  snake 
  

   is 
  attempting 
  to 
  swallow 
  it. 
  The 
  amount 
  of 
  venom 
  delivered 
  at 
  one 
  

   strike 
  varies 
  greatly 
  even 
  in 
  the 
  same 
  individual. 
  If 
  the 
  snake 
  is 
  in 
  

   poor 
  condition, 
  if 
  it 
  has 
  already 
  struck 
  recently, 
  or 
  if 
  the 
  fangs 
  have 
  

   to 
  penetrate 
  layers 
  of 
  hide, 
  fur, 
  and 
  fat 
  — 
  or 
  in 
  the 
  case 
  of 
  human 
  

   beings, 
  clothing 
  or 
  shoes 
  — 
  the 
  amount 
  of 
  poison 
  that 
  may 
  be 
  injected 
  

   is 
  correspondingly 
  less 
  than 
  normal. 
  The 
  diamondback 
  rattler 
  of 
  the 
  

   southeastern 
  United 
  States 
  is 
  our 
  largest 
  species 
  and 
  hence 
  has 
  

   probably 
  the 
  longest 
  fangs 
  — 
  about 
  three-quarters 
  of 
  an 
  inch 
  in 
  a 
  

   6-foot 
  snake. 
  The 
  fangs 
  at 
  rest 
  are 
  covered 
  by 
  whitish 
  folds 
  of 
  skin, 
  

   very 
  apparent 
  when 
  the 
  snake 
  opens 
  its 
  mouth. 
  

  

  Additional 
  facts 
  about 
  pit 
  vipers. 
  — 
  It 
  is 
  a 
  popular 
  but 
  erroneous 
  

   belief 
  that 
  a 
  rattler's 
  age 
  is 
  told 
  by 
  counting 
  the 
  "rings" 
  in 
  its 
  rattle. 
  

   The 
  fact 
  is 
  that 
  a 
  segment 
  is 
  formed 
  every 
  time 
  the 
  growing 
  snake 
  

   sheds 
  its 
  skin 
  ; 
  hence 
  a 
  young 
  snake 
  acquires 
  three 
  or 
  four 
  during 
  its 
  

   first 
  year 
  of 
  life, 
  and 
  about 
  as 
  many 
  more 
  each 
  year 
  during 
  its 
  later 
  

   years. 
  By 
  the 
  time 
  it 
  has 
  reached 
  nearly 
  maximum 
  growth, 
  it 
  often 
  

   accidentally 
  breaks 
  off 
  most 
  of 
  its 
  rattle 
  — 
  which 
  is 
  composed 
  merely 
  of 
  

   segments 
  of 
  a 
  dried, 
  horny 
  substance 
  — 
  so 
  that 
  a 
  very 
  large 
  snake 
  pre- 
  

   sumably 
  several 
  years 
  old 
  may 
  have 
  only 
  one 
  or 
  two 
  segments. 
  Circus 
  

   men 
  overcome 
  that 
  difficulty 
  by 
  fitting 
  several 
  rattles 
  onto 
  a 
  big 
  

   snake's 
  tail 
  to 
  make 
  it 
  more 
  imposing 
  to 
  the 
  trusting 
  audience. 
  

  

  The 
  colors 
  of 
  most 
  pit 
  vipers 
  are 
  much 
  duller 
  than 
  those 
  of 
  the 
  

   brilliant 
  coral 
  snake 
  previously 
  discussed. 
  Rattlers 
  especially 
  are 
  in- 
  

   clined 
  to 
  dull, 
  dark 
  tones 
  as 
  they 
  reach 
  adulthood, 
  and 
  this 
  effect 
  is 
  

   increased 
  by 
  the 
  keels 
  of 
  the 
  lusterless 
  scales 
  which 
  further 
  roughen 
  

  

  