﻿[27] 
  DEVELOPMENT 
  OF 
  OSSEOUS 
  FISHES. 
  515 
  

  

  spins 
  from 
  a 
  pore 
  or 
  pores 
  behind 
  the 
  vent, 
  while 
  he 
  uses 
  his 
  bobbin- 
  

   shaped 
  body 
  to 
  insinuate 
  himself 
  through 
  the 
  interstices 
  through 
  which 
  

   he 
  carries 
  his 
  thread 
  with 
  which 
  he 
  binds 
  a 
  few 
  stalks 
  of 
  Anacharis 
  or 
  

   other 
  water-weeds 
  together, 
  bringing 
  in 
  his 
  mouth 
  every 
  now 
  and 
  then 
  

   a 
  contribution 
  of 
  some 
  sort 
  in 
  the 
  shape 
  of 
  a 
  bit 
  of 
  a 
  dead 
  plant 
  or 
  other 
  

   object, 
  which 
  he 
  binds 
  into 
  the 
  little 
  cradle 
  in 
  which 
  the 
  young 
  are 
  to 
  

   be 
  hatched. 
  The 
  thread 
  is 
  spun 
  fitfully, 
  not 
  continuously. 
  He 
  will 
  go 
  

   round 
  and 
  round 
  the 
  nest 
  for 
  perhaps 
  a 
  dozen 
  times, 
  when 
  he 
  will 
  rest 
  

   awhile 
  and 
  begin 
  again, 
  or 
  turn 
  suddenly 
  round 
  and 
  force 
  his 
  snout 
  

   into 
  its 
  top 
  with 
  a 
  vigorous 
  plunging 
  motion, 
  as 
  if 
  to 
  get 
  it 
  into 
  the 
  

   proper 
  shape. 
  Its 
  shape 
  is 
  somewhat 
  like 
  an 
  inverted 
  truncated 
  cone; 
  

   an 
  opening 
  is 
  left 
  at 
  the 
  top 
  through 
  which 
  it 
  is 
  supposed 
  that 
  he 
  intro- 
  

   duces 
  the 
  eggs. 
  The 
  thread 
  is 
  wound 
  round 
  and 
  round 
  the 
  nest 
  in 
  a 
  

   horizontal 
  direction 
  in 
  the 
  case 
  we 
  are 
  describing, 
  and 
  if 
  this 
  thread 
  is 
  

   placed 
  under 
  the 
  microscope 
  when 
  freshly 
  spun 
  it 
  is 
  found 
  to 
  be 
  com- 
  

   posed 
  of 
  very 
  thin 
  transparent 
  fibers 
  to 
  the 
  number 
  of 
  six 
  or 
  eight; 
  

   where 
  they 
  are 
  broken 
  off 
  or 
  terminate 
  they 
  have 
  attenuated 
  tapering 
  

   ends, 
  as 
  though 
  the 
  material 
  of 
  which 
  they 
  were 
  made 
  had 
  been 
  ex- 
  

   hausted 
  when 
  the 
  spinning 
  ceased. 
  Very 
  soon 
  after 
  the 
  thread 
  is 
  spun 
  

   particles 
  of 
  dirt 
  adhere 
  to 
  it 
  and 
  render 
  it 
  difficult 
  to 
  interpret 
  its 
  char- 
  

   acter. 
  I 
  have 
  seen 
  the 
  thread 
  being 
  drawn 
  out 
  from 
  the 
  abdomen 
  re- 
  

   peatedly, 
  but 
  not 
  from 
  the 
  vent; 
  it 
  appeared 
  to 
  me 
  more 
  probable 
  that 
  

   it 
  came 
  from 
  the 
  openings 
  of 
  a 
  special 
  spinning 
  gland. 
  Its 
  glass-like 
  

   transparency 
  shows 
  that 
  it 
  is 
  not 
  made 
  up 
  of 
  ingested 
  food, 
  the 
  parti- 
  

   cles 
  of 
  which 
  would 
  exhibit 
  themselves 
  were 
  that 
  the 
  case. 
  The 
  nest 
  

   measures 
  half 
  an 
  inch 
  in 
  height 
  and 
  three-eighths 
  in 
  diameter. 
  

  

  " 
  Upon 
  opening 
  the 
  male 
  I 
  find 
  a 
  large 
  vesicle 
  filled 
  with 
  a 
  clear, 
  ex- 
  

   tremely 
  viscid 
  secretion 
  which 
  coagulates 
  into 
  threads 
  upon 
  contact 
  

   with 
  water. 
  This 
  vesicle 
  appears 
  to 
  open 
  directly 
  behind* 
  the 
  vent, 
  

   separately 
  from 
  the 
  latter. 
  It 
  measures 
  one-fifth 
  inch 
  in 
  length 
  and 
  an 
  

   eighth 
  in 
  diameter. 
  As 
  soon 
  as 
  it 
  is 
  ruptured 
  it 
  loses 
  its 
  transparency, 
  

   and 
  whatever 
  secretion 
  escapes 
  becomes 
  whitish 
  after 
  being 
  in 
  contact 
  

   with 
  water 
  for 
  a 
  short 
  time. 
  This 
  has 
  the 
  same 
  tough, 
  elastic 
  qualities 
  as 
  

   when 
  spun 
  by 
  the 
  animal 
  itself, 
  and 
  is 
  also 
  composed 
  of 
  numerous 
  fibers, 
  

   as 
  when 
  a 
  portion 
  is 
  taken 
  which 
  has 
  been 
  recently 
  spun 
  upon 
  the 
  nest. 
  

   The 
  nature 
  of 
  the 
  opening 
  was 
  not 
  learned 
  with* 
  precision, 
  as 
  I 
  possessed 
  

   only 
  a 
  single 
  specimen. 
  The 
  vesicle 
  lies 
  to 
  the 
  right 
  side 
  of 
  the 
  intes- 
  

   tine, 
  and 
  there 
  is 
  very 
  little 
  doubt 
  that 
  it 
  opens 
  behind 
  the 
  anus. 
  The 
  

   testes 
  are 
  two 
  ovoid 
  glands, 
  the 
  ducts 
  of 
  which 
  unite 
  into 
  a 
  common 
  

   canal, 
  both 
  glands 
  and 
  ducts 
  being 
  covered 
  with 
  black 
  pigment 
  cells 
  ; 
  

   the 
  testes, 
  during 
  the 
  breeding 
  season, 
  measure 
  somewhat 
  less 
  than 
  an 
  

   eighth 
  of 
  an 
  inch 
  in 
  length. 
  As 
  to 
  the 
  origin 
  of 
  the 
  secretion 
  I 
  have 
  

  

  * 
  By 
  mistake 
  it 
  is 
  stated, 
  in 
  this 
  paragraph 
  of 
  niy 
  original 
  account, 
  that 
  the 
  sac 
  

   opens 
  " 
  in 
  front 
  of 
  the 
  vent." 
  I 
  make 
  the 
  needed 
  correction 
  here, 
  as 
  I 
  find 
  that 
  the 
  

   sketches 
  which 
  I 
  made 
  at 
  the 
  time 
  show 
  that 
  it 
  opened 
  behind 
  the 
  vent, 
  as 
  stated 
  in 
  

   the 
  first 
  paragraph. 
  

  

  