﻿ECmUHOID 
  WOHMS 
  OF 
  XOHTH 
  PACIFIC 
  — 
  FISHER 
  275 
  

  

  ventral 
  sctji) 
  is 
  now 
  apparent, 
  if 
  wo 
  linve 
  faith 
  in 
  the 
  cfTicacy 
  of 
  use 
  

   and 
  nonuse 
  in 
  (Joterniining 
  the 
  rehitive 
  size 
  of 
  siniihir 
  orpins. 
  

  

  Castings 
  are 
  sometimes 
  ejected 
  fioni 
  the 
  burrow 
  by 
  tliis 
  flipping 
  of 
  

   the 
  posterior 
  end 
  of 
  the 
  body 
  (wliieh 
  ean 
  be 
  aihnirably 
  imitated 
  with 
  

   the 
  forefinger), 
  but 
  usually 
  only 
  by 
  water 
  currents. 
  Castings 
  are 
  

   allowed 
  to 
  accumulate 
  and 
  then 
  are 
  ejected 
  in 
  (juantity 
  from 
  one 
  

   entrance. 
  When 
  digging 
  downhill 
  the 
  animal 
  shoves 
  the 
  soil 
  along 
  

   the 
  body 
  and 
  then 
  out 
  by 
  backing 
  up 
  the 
  burrow, 
  forcing 
  the 
  sand 
  out 
  

   the 
  last 
  inch 
  or 
  two 
  by 
  water 
  currents. 
  The 
  opening 
  then 
  resembles 
  

   a 
  miniature 
  vok-ano 
  with 
  line 
  dark 
  sand 
  sj)outing 
  out 
  and 
  the 
  roily 
  

   water 
  trailing 
  oil' 
  from 
  the 
  crater 
  like 
  smoke. 
  A 
  major 
  convulsion 
  

   will 
  carry 
  out 
  fragments 
  of 
  shells 
  2 
  or 
  3 
  mm. 
  in 
  section. 
  Larger 
  

   objects 
  are 
  avoided 
  or 
  allowed 
  to 
  fall 
  toward 
  the 
  lower 
  part 
  of 
  the 
  

   burrow 
  where 
  the}' 
  are 
  buried. 
  Doubling 
  the 
  velocity 
  of 
  water 
  in- 
  

   creases 
  its 
  carrying 
  efficiency 
  directly 
  as 
  the 
  sixth 
  power. 
  'J'hc 
  nar- 
  

   rowed 
  mouth 
  of 
  the 
  tunnel 
  undoubtedly 
  aids 
  in 
  increasing 
  the 
  force 
  

   of 
  these 
  "volcanic" 
  manifestations 
  and 
  hence 
  their 
  efficiency 
  in 
  re- 
  

   moving 
  sizable 
  debris. 
  

  

  Once 
  Urechis 
  is 
  settled 
  in 
  a 
  permanent 
  home 
  its 
  daily 
  activities 
  

   consist 
  of 
  respiratory 
  movements, 
  obtaining 
  food, 
  cleaning 
  the 
  bur- 
  

   row, 
  and 
  resting. 
  

  

  Hespiratory 
  7noreme7tts. 
  — 
  There 
  are 
  two 
  separate 
  movements 
  con- 
  

   cerned 
  with 
  the 
  respiration 
  of 
  Urechis: 
  (1) 
  The 
  peristaltic 
  movements 
  

   along 
  the 
  bod\' 
  which 
  pump 
  fresh 
  water 
  into 
  the 
  tunnel 
  and 
  move 
  

   that 
  within 
  respirator}' 
  chamber 
  of 
  the 
  intestine; 
  (2) 
  the 
  inhalations 
  

   and 
  exhalations, 
  through 
  the 
  anus, 
  for 
  which 
  the 
  muscular 
  cloacal 
  

   chamber, 
  resembling 
  that 
  of 
  a 
  holothurian, 
  su|)i)lies 
  the 
  ciiief 
  motive, 
  

   power. 
  

  

  The 
  inhalations 
  are 
  from 
  1 
  to 
  upward 
  of 
  30 
  iji 
  succession 
  (witliout 
  

   an 
  exhalation). 
  Exhalation 
  is 
  usually 
  a 
  single 
  discharge 
  although 
  

   infrefjuently 
  a 
  rest 
  may 
  occur 
  duiing 
  a 
  period 
  of 
  exhalation. 
  The 
  

   rote 
  of 
  breathing 
  is 
  not 
  uniform. 
  For 
  instaiu'c, 
  2 
  inspirations 
  cover- 
  

   ing 
  25 
  seconds 
  were 
  followed 
  by 
  an 
  expiration 
  period 
  of 
  10 
  seconds, 
  

   whil(! 
  in 
  another 
  instance 
  7 
  inspiiations 
  occupied 
  2") 
  seconds, 
  the 
  ex- 
  

   piration 
  10; 
  24 
  hisj)irations 
  occuj)ied 
  70 
  secojuls, 
  the 
  single 
  expiration 
  

   50; 
  30 
  inspirations 
  occupied 
  90 
  seconds, 
  the 
  expirations 
  only 
  25. 
  

   Inspirations 
  fewer 
  than 
  12 
  predominate 
  in 
  a 
  total 
  of 
  11 
  cycles 
  timed. 
  

   These 
  tinu's 
  were 
  tak(;n 
  on 
  a 
  specimen 
  lying 
  in 
  a 
  pan 
  of 
  water. 
  In 
  

   its 
  natural 
  environnient 
  Urechis 
  bi-eath(!S 
  more 
  .'^lowly, 
  but 
  with 
  the 
  

   same 
  irregidarily. 
  

  

  The 
  peristaltic 
  movements 
  of 
  the 
  body 
  which 
  serve 
  to 
  propel 
  water 
  

   thr(tugh 
  the 
  tul»(' 
  are 
  oven 
  more 
  erratic. 
  The 
  wa\'e, 
  which 
  expands 
  

   the 
  body 
  to 
  lill 
  the 
  burrow, 
  begins 
  at 
  the 
  base 
  of 
  the 
  j)roboscis 
  and 
  

   passes 
  along 
  the 
  body 
  at 
  varying 
  rates 
  for 
  dilferent 
  waves 
  or 
  even 
  the 
  

   same 
  wave 
  in 
  diirereul 
  parts 
  of 
  the 
  body. 
  As 
  one 
  wave 
  arrives 
  at 
  the 
  

  

  