﻿PACKAED.J 
  PARASITES 
  OF 
  THE 
  LOCUST. 
  665 
  

  

  its 
  life. 
  Plate 
  LXIII, 
  Fig. 
  7,/, 
  represents 
  the 
  embryo 
  of 
  Gordius 
  aqua- 
  

   ticus 
  greatly 
  inaguifiecl. 
  It 
  will 
  be 
  seen 
  how 
  greatly 
  it 
  differs 
  from 
  the 
  

   adult 
  hair-worm, 
  having 
  in 
  this 
  stage 
  some 
  resemblance 
  to 
  the 
  Acan^/io- 
  

   cejphalus 
  bj' 
  its 
  cephalic 
  armature, 
  to 
  the-yematoic/ectorthread-worms 
  by 
  its 
  

   alimentary 
  canal; 
  and 
  to 
  the 
  larvre 
  [cercaria) 
  of 
  the 
  Tremotodes 
  or 
  fluke- 
  

   worms 
  in 
  the 
  nature 
  of 
  its 
  secretory 
  glands. 
  But 
  the 
  hair-worm 
  differs 
  

   from 
  all 
  these 
  worms 
  and 
  even 
  biennis, 
  a 
  hair-worm 
  much 
  like 
  and 
  

   easily 
  confounded 
  with 
  Gordius, 
  in 
  having 
  a 
  complete 
  metamorphosis 
  

   after 
  leaving 
  the 
  egg.* 
  

  

  When 
  in 
  this 
  stage, 
  it 
  incessantly 
  protrudes 
  and 
  retracts 
  its 
  armed 
  

   head, 
  the 
  spines 
  being 
  directed 
  backward 
  when 
  the 
  head 
  is 
  out. 
  

  

  In 
  the 
  first 
  period 
  of 
  larval 
  life 
  the 
  worm 
  lives 
  encysted 
  in 
  the 
  bodies 
  

   of 
  aquatic 
  fly-larvoe. 
  The 
  vessel 
  in 
  which 
  M. 
  Villot 
  put 
  his 
  Gordius 
  

   eggs 
  also 
  contained 
  the 
  larvte 
  of 
  Tanapus, 
  Gorethra, 
  and 
  Ghironomas, 
  

   small 
  gnat-like 
  flies. 
  He 
  found 
  that 
  each 
  of 
  these 
  larvss 
  contained 
  num- 
  

   erous 
  cysts 
  with 
  larvce 
  of 
  Gordius. 
  He 
  then 
  removed 
  the 
  larvse 
  from 
  

   the 
  cysts, 
  placed 
  them 
  on 
  the 
  gnat-larva, 
  and 
  saw 
  the 
  larval 
  hair-worm 
  

   work 
  its 
  way 
  into 
  the 
  head 
  of 
  the 
  gnat-larva 
  through 
  the 
  softer 
  part 
  

   of 
  the 
  integument 
  ; 
  during 
  the 
  process 
  the 
  spines 
  on 
  the 
  head, 
  reversing 
  

   their 
  usual 
  position, 
  enabled 
  the 
  worm 
  to 
  retain 
  its 
  position 
  and 
  pene- 
  

   trate 
  farther 
  in. 
  Then, 
  finding 
  a 
  suitable 
  place, 
  it 
  came 
  to 
  rest 
  and 
  re- 
  

   mained 
  immovable. 
  Then 
  the 
  fluids 
  bathing 
  the 
  parts 
  coagulated 
  and 
  

   formed 
  a 
  hard, 
  granulated 
  sac. 
  This 
  sac 
  at 
  first 
  closely 
  envelopes 
  the 
  

   body, 
  then 
  it 
  becomes 
  looser 
  and 
  longer, 
  the 
  worm 
  living 
  in 
  the 
  anterior 
  

   part, 
  the 
  front 
  end 
  of 
  the 
  sac 
  being 
  probably 
  never 
  closed. 
  In 
  this 
  first 
  

   larval 
  state 
  the 
  worm 
  is 
  active. 
  

  

  In 
  the 
  second 
  larval 
  period, 
  the 
  young 
  hair-worm 
  lives 
  motionless 
  and 
  

   enc3"Sted 
  in 
  the 
  mucous 
  layer 
  of 
  the 
  intestines 
  of 
  small 
  fish, 
  which 
  prey 
  

   on 
  the 
  gnat-larvoe. 
  A 
  minnow, 
  for 
  example, 
  swallowing 
  one 
  of 
  the 
  

   aquatic 
  gnat-larvte, 
  the 
  encysted 
  larva 
  becomes 
  set 
  free 
  by 
  the 
  process 
  

   of 
  digestion 
  in 
  the 
  stomach 
  of 
  the 
  fish; 
  the 
  cyst 
  dissolving 
  the 
  young 
  

   hair-worm 
  itself 
  becomes 
  free 
  in 
  the 
  intestine 
  of 
  its 
  new 
  host. 
  Imme- 
  

   diately 
  it 
  begins 
  to 
  bore, 
  aided 
  by 
  the 
  spines 
  around 
  the 
  head, 
  into 
  the 
  

   mucous 
  membrane 
  lining 
  the 
  inner 
  wall 
  of 
  the 
  intestine 
  of 
  the 
  fish, 
  and 
  

   then 
  become 
  encysted, 
  the 
  worm 
  itself 
  lying 
  motionless 
  in 
  its 
  new 
  home, 
  

   with 
  its 
  head 
  retracted 
  and 
  the 
  tail 
  rolled 
  in 
  a 
  spiral. 
  The 
  cyst 
  is 
  either 
  

   spherical 
  or 
  oval. 
  (Plate 
  LXIII, 
  Fig. 
  6, 
  g.) 
  

  

  The 
  return 
  to 
  a 
  free 
  state 
  and 
  an 
  aquatic 
  life 
  occurs 
  in 
  the 
  spring, 
  five 
  

   or 
  six 
  months 
  after 
  the 
  second 
  encystment. 
  It 
  then 
  bores 
  through 
  its 
  

   cj'st, 
  and 
  passes 
  into 
  the 
  intestinal 
  cavity 
  of 
  the 
  fish, 
  and 
  from 
  thence 
  

   is 
  carried 
  out 
  with 
  the 
  fseces 
  into 
  the 
  water. 
  On 
  contact 
  with 
  the 
  water 
  

   great 
  changes 
  take 
  place. 
  The 
  numerous 
  transverse 
  folds 
  in 
  the 
  body 
  

   disappear, 
  and 
  it 
  becomes 
  twice 
  as 
  long 
  as 
  before, 
  its 
  head-armature 
  

   disappears, 
  the 
  body 
  becomes 
  swollen, 
  milky, 
  and 
  pulpy. 
  It 
  remains 
  

   immovable 
  in 
  the 
  water 
  for 
  a 
  variable 
  period, 
  and 
  then 
  increases 
  in 
  

   size, 
  the 
  integument 
  grows 
  harder, 
  and 
  when 
  about 
  two 
  inches 
  long 
  it 
  

   turns 
  brown 
  and 
  begins 
  to 
  move. 
  Probably 
  the 
  host 
  differs 
  according 
  

   to 
  chance. 
  Most 
  of 
  those 
  which 
  have 
  occurred 
  in 
  Europe 
  reside 
  in 
  

  

  "* 
  It 
  uKty 
  here 
  be 
  said 
  that 
  iu 
  the 
  Mcrmis 
  hair-worm, 
  "which 
  also 
  lives 
  in 
  insects, 
  and 
  is 
  

   of 
  the 
  same 
  general 
  appearance 
  as 
  Gordius, 
  the 
  young 
  when 
  hatched 
  is 
  not 
  annulate, 
  

   has 
  no 
  cephalic 
  armature, 
  while 
  the 
  body 
  is 
  short 
  and 
  thick, 
  the 
  tail 
  blunt. 
  These 
  re- 
  

   marks 
  are 
  based 
  on 
  some 
  drawings 
  of 
  the 
  eggs 
  and 
  embryos 
  of 
  a 
  Mermis 
  made 
  by 
  Mr. 
  

   James 
  H. 
  Smerton, 
  in 
  Jena 
  (May, 
  1876), 
  and 
  kindly 
  given 
  me 
  by 
  him. 
  The 
  female 
  

   genital 
  apperture 
  is 
  situated 
  iu 
  the 
  middle 
  of 
  the 
  body, 
  while 
  it 
  is 
  placed 
  at 
  the 
  end 
  of 
  

   the 
  body 
  in 
  Gordius, 
  leading 
  out 
  of 
  a 
  cloacal 
  chamber 
  in 
  which 
  the 
  Intestine 
  and 
  two 
  

   different 
  ducts 
  (male 
  or 
  female, 
  as 
  the 
  case 
  may 
  be) 
  terminate, 
  the 
  common 
  external 
  

   aperture 
  being 
  ano-genital 
  in 
  its 
  nature. 
  

  

  