﻿OCT. 
  4, 
  1922 
  STEINER 
  AND 
  HEINLY 
  : 
  CONTROL 
  OF 
  INJURIOUS 
  NEMAS 
  

  

  379 
  

  

  of 
  the 
  sense 
  organs 
  of 
  touch 
  seemed 
  to 
  be 
  its 
  chief 
  method 
  of 
  locating 
  

   food. 
  We 
  could 
  therefore 
  confirm 
  statements 
  made 
  by 
  Menzel 
  about 
  

   this 
  matter. 
  

  

  As 
  soon 
  as 
  the 
  head 
  end 
  of 
  a 
  mononch 
  came 
  into 
  contact 
  with 
  its 
  

   prey, 
  it 
  grasped 
  it 
  tightly. 
  By 
  a 
  sucking 
  movement, 
  probably 
  of 
  the 
  

   oesophageal 
  muscles, 
  the 
  head 
  was 
  fixed 
  to 
  the 
  prey. 
  The 
  nematode 
  

   caught 
  by 
  the 
  mononch 
  naturally 
  made 
  most 
  violent 
  efforts 
  to 
  get 
  

   free, 
  and 
  often 
  the 
  mononch 
  was 
  shaken 
  and 
  dragged 
  along. 
  But 
  it 
  

   held 
  on 
  tightly 
  and 
  soon 
  its 
  tooth 
  and 
  other 
  mouth 
  parts 
  began 
  to 
  work. 
  

   By 
  a 
  sucking 
  movement 
  of 
  the 
  oesophagus 
  and 
  mouth 
  cavity, 
  the 
  mo- 
  

   nonch 
  became 
  more 
  firmly 
  fixed 
  to 
  its 
  prey, 
  when 
  the 
  tooth 
  located 
  on 
  

   the 
  dorsal 
  wall 
  was 
  protruded 
  and 
  produced 
  an 
  opening 
  in 
  the 
  skin 
  of 
  the 
  

   victim. 
  Then 
  a 
  stronger 
  

   (or 
  further) 
  sucking 
  ac- 
  

   tion 
  was 
  exerted 
  by 
  the 
  

   mononch 
  and 
  the 
  tooth 
  

   came 
  back 
  to 
  its 
  normal 
  

   position. 
  The 
  whole 
  

   oesophagus 
  came 
  often 
  

   into 
  action 
  and 
  moved 
  

   forward 
  and 
  backward 
  

   with 
  the 
  intestine, 
  the 
  

   whole 
  body 
  going 
  

   through 
  the 
  same 
  move- 
  

   ments; 
  first 
  the 
  body 
  

   fluid 
  of 
  the 
  prey 
  was 
  

   sucked 
  out, 
  and 
  as 
  this 
  

   happened 
  its 
  body 
  be- 
  

   came 
  shrunken. 
  Very 
  

   often 
  the 
  mononch 
  was 
  

   satisfied 
  with 
  this, 
  and 
  

   set 
  free 
  its 
  prey, 
  which 
  

   died 
  shortly 
  afterwards. 
  

   Specimens 
  of 
  Rhabditis 
  

   elegans 
  killed 
  in 
  this 
  way 
  

   are 
  pictured 
  in 
  Fig. 
  3. 
  

  

  M. 
  papillatus 
  rarely 
  devoured 
  an 
  entire 
  animal 
  when 
  feeding 
  on 
  large 
  

   forms, 
  except 
  when 
  exceedingly 
  hungry. 
  No 
  one 
  part 
  of 
  the 
  victim's 
  

   body 
  seemed 
  to 
  be 
  preferable 
  for 
  attack, 
  the 
  prey 
  being 
  seized 
  at 
  ran- 
  

   dom. 
  Fig. 
  4 
  shows 
  an 
  Anguillula 
  aceti 
  attacked 
  near 
  the 
  cardia, 
  and 
  

  

  Fig. 
  4. 
  Photograph 
  of 
  a 
  mononch 
  attacking 
  an 
  Anguillula 
  

   aceti 
  near 
  the 
  cardia. 
  Photograph 
  taken 
  from 
  an 
  agar- 
  

   plate. 
  

  

  Fig. 
  5. 
  Sketch 
  of 
  the 
  head-end 
  of 
  a 
  mononch 
  attacking 
  

   a 
  larval 
  Rhabditis. 
  Notice 
  the 
  wide 
  opened 
  lips 
  and 
  

   the 
  protruded 
  tooth. 
  

  

  