﻿610 
  GI50RGE 
  WAGNKR. 
  

  

  but 
  this 
  is 
  not 
  at 
  all 
  tlie 
  case. 
  The 
  actual 
  process 
  of 
  swallow- 
  

   ing 
  depends 
  entirely 
  on 
  the 
  activity 
  of 
  the 
  tissue 
  of 
  the 
  hypo- 
  

   stome 
  and 
  body. 
  Occasionally 
  a 
  tentacle 
  remains 
  attached 
  

   to 
  a 
  food 
  particle 
  after 
  the 
  mouth 
  has 
  opened, 
  and 
  in 
  some 
  

   cases 
  the 
  tentacle 
  is 
  even 
  drawn 
  into 
  the 
  food 
  cavity 
  with 
  the 
  

   food. 
  But 
  in 
  all 
  such 
  cases 
  which 
  have 
  come 
  under 
  my 
  

   notice 
  it 
  could 
  be 
  seen 
  that 
  the 
  tentacle 
  was 
  passively 
  pulled 
  

   along, 
  having 
  by 
  its 
  nematocysts, 
  or 
  in 
  some 
  other 
  way, 
  

   become 
  attached 
  to 
  the 
  food, 
  and 
  being 
  unable 
  to 
  release 
  its 
  

   hold. 
  

  

  Fig. 
  5. 
  — 
  Hydi-a 
  f^risea, 
  with 
  partially 
  ingested 
  annelid. 
  

   (Camera 
  lucida 
  drawing.) 
  

  

  The 
  food 
  is 
  now 
  slowly 
  drawn 
  into 
  the 
  body 
  cavity, 
  but 
  at 
  

   the 
  same 
  time 
  another 
  movement 
  takes 
  place. 
  The 
  hypostome 
  

   slowly 
  draws 
  itself 
  upwards 
  over 
  the 
  food 
  particle. 
  This 
  

   peculiar 
  action 
  is 
  very 
  well 
  compared 
  by 
  Hartog 
  (1. 
  c.) 
  to 
  the 
  

   method 
  in 
  which 
  a 
  snake 
  gets 
  outside 
  its 
  prey, 
  or 
  in 
  which 
  an 
  

   automatic 
  stocking 
  might 
  stretch 
  itself 
  onto 
  the 
  foot 
  and 
  leg. 
  

   The 
  food 
  once 
  well 
  within 
  the 
  cavity 
  the 
  mouth 
  closes. 
  Now 
  

   the 
  body-wall 
  expands 
  for 
  some 
  distance 
  in 
  front 
  of 
  the 
  

   particle, 
  while 
  it 
  strongly 
  contracts 
  behind 
  it. 
  And 
  so 
  the 
  

   food 
  is 
  forced 
  to 
  the 
  lower 
  portion 
  of 
  the 
  food 
  cavity. 
  

  

  Both 
  cilia 
  and 
  pseudopodia 
  have 
  been 
  observed 
  on 
  the 
  

   ectodermal 
  cells 
  of 
  Hydra, 
  and 
  it 
  is 
  commonly 
  stated 
  that 
  it 
  

   is 
  the 
  former 
  that 
  are 
  chiefly 
  concerned 
  in 
  the 
  act 
  of 
  swallow- 
  

   ing. 
  But 
  it 
  is 
  difficult 
  to 
  see 
  how 
  cilia 
  could 
  have 
  enough 
  

   strength 
  to 
  play 
  any 
  part 
  in 
  the 
  swallowing 
  of 
  entire 
  entorao- 
  

  

  