﻿334 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  again 
  and 
  again 
  subdivide. 
  If 
  these 
  are 
  noted 
  and 
  it 
  is 
  observed 
  that 
  they 
  are 
  

   engorged, 
  giving 
  them 
  the 
  appearance 
  of 
  a 
  simple 
  series 
  of 
  much-branched 
  great 
  

   veins 
  filled 
  with 
  creamy 
  white 
  contents, 
  it 
  may 
  be 
  certainly 
  presumed 
  that 
  your 
  

   specimen 
  is 
  mature 
  and 
  that 
  spawn 
  may 
  be 
  readily 
  pressed 
  from 
  it. 
  

  

  The 
  operation 
  of 
  pressing 
  the 
  sijawn 
  out 
  of 
  the 
  ducts 
  requires 
  care. 
  The 
  side 
  of 
  

   the 
  end 
  of 
  the 
  pipette 
  may 
  be 
  used, 
  being 
  careful 
  not 
  to 
  crush 
  or 
  break 
  open 
  the 
  

   ducts 
  as 
  you 
  gently 
  and 
  firmly 
  stroke 
  the 
  pipetto 
  flatwise 
  over 
  the 
  side 
  of 
  the 
  

   visceral 
  mass 
  backward 
  from 
  the 
  hinge 
  toward 
  the 
  heart 
  space 
  and 
  over 
  the 
  great 
  

   duct 
  at 
  the 
  border 
  of 
  the 
  latter 
  diagonally 
  downward 
  and 
  backward 
  to 
  the 
  opening 
  

   of 
  the 
  reproductive 
  organ. 
  If 
  this 
  has 
  been 
  properly 
  done 
  it 
  will 
  be 
  found 
  that 
  the 
  

   generative 
  products 
  are 
  being 
  'pushed 
  forward 
  by'the 
  pipette 
  through 
  the 
  ducts, 
  as 
  

   the 
  pressure 
  will 
  be 
  seen 
  to 
  distend 
  the 
  latter, 
  the 
  contents 
  of 
  the 
  branches 
  flowing 
  

   into 
  the 
  larger 
  and 
  larger 
  trunks 
  iiutil 
  they 
  are 
  forced 
  outward 
  through 
  the 
  main 
  

   duct 
  and 
  openiug 
  below 
  the 
  great 
  adductor, 
  where 
  they 
  will 
  pour 
  out 
  in 
  a 
  stream 
  

   one-sixteenth 
  of 
  an 
  inch 
  or 
  more 
  in 
  diameter 
  if 
  the 
  products 
  are 
  perfectly 
  ripe. 
  The 
  

   sexes 
  may 
  be 
  discriminated 
  as 
  described 
  at 
  the 
  outset, 
  and 
  it 
  is 
  well 
  to 
  first 
  find 
  a 
  

   male 
  by 
  the 
  method 
  already 
  given 
  and 
  proceed 
  to 
  express 
  the 
  milt 
  as 
  described 
  

   above 
  into, 
  say, 
  a 
  gill 
  of 
  sea 
  water, 
  adding 
  pipetteful 
  after 
  pipetteful 
  until 
  it 
  acquires 
  

   a 
  milky 
  or 
  opalescent 
  white 
  color. 
  As 
  the 
  milt 
  or 
  eggs 
  are 
  pressed 
  out 
  of 
  the 
  open- 
  

   ing 
  of 
  the 
  ducts, 
  they 
  are 
  to 
  be 
  sucked 
  up 
  by 
  the 
  pipette 
  and 
  dropped 
  into 
  the 
  water, 
  

   the 
  mixture 
  of 
  milt 
  being 
  first 
  prepared, 
  to 
  which 
  the 
  eggs 
  may 
  be 
  added 
  as 
  they 
  

   are 
  expressed 
  from 
  the 
  females. 
  The 
  judgment 
  of 
  the 
  operator 
  is 
  to 
  be 
  used 
  in 
  mix- 
  

   ing 
  the 
  liquids 
  ; 
  in 
  practice 
  I 
  find 
  that 
  one 
  male 
  Avill 
  supply 
  enough 
  milt 
  to 
  fertilize 
  

   the 
  eggs 
  obtained 
  from 
  three 
  or 
  four 
  females, 
  and 
  it 
  does 
  not 
  matter 
  if 
  the 
  operation 
  

   takes 
  from 
  twenty 
  to 
  thirty 
  minutes' 
  time, 
  as 
  the 
  male 
  fluid, 
  which 
  it 
  is 
  best 
  to 
  

   prepare 
  first, 
  will 
  retain 
  its 
  vitality 
  for 
  that 
  period. 
  

  

  It 
  is 
  always 
  desirable 
  to 
  be 
  as 
  careful 
  as 
  possible 
  not 
  to 
  get 
  fragments 
  of 
  other 
  

   tissues 
  mixed 
  with 
  the 
  eggs 
  and 
  milt, 
  and 
  the 
  admixture 
  of 
  dirt 
  of 
  any 
  kind 
  is 
  to 
  be 
  

   avoided. 
  To 
  separate 
  any 
  such 
  fragments 
  nicely, 
  I 
  find 
  a 
  small 
  strainer 
  of 
  coarse 
  

   bolting 
  or 
  cheese 
  cloth 
  to 
  be 
  very 
  convenient. 
  

  

  In 
  the 
  foregoing 
  description 
  we 
  have 
  described 
  the 
  method 
  of 
  obtaining 
  the 
  spawn 
  

   only 
  from 
  the 
  side 
  of 
  the 
  animal 
  exposed 
  in 
  opening 
  the 
  shell, 
  A 
  little 
  experience 
  

   will 
  enable 
  one 
  to 
  lift 
  up 
  the 
  head 
  end 
  of 
  the 
  animal 
  and 
  throw 
  it 
  back 
  over 
  the 
  great 
  

   adductor 
  muscle, 
  expose 
  the 
  opening 
  of 
  the 
  reproductive 
  organ 
  on 
  the 
  left 
  side, 
  

   or 
  whatever 
  the 
  case 
  may 
  be, 
  and 
  also 
  express 
  the 
  spawn 
  from 
  that 
  side, 
  thus 
  as 
  

   efi'ectually 
  obtaining 
  all 
  of 
  the 
  ripe 
  eggs 
  or 
  milt 
  as 
  is 
  possible 
  in 
  the 
  process 
  of 
  

   taking 
  the 
  ^ame 
  from 
  fishes. 
  

  

  It 
  is 
  remarkable 
  to 
  note 
  the 
  success 
  attending 
  this 
  method, 
  since 
  almost 
  every 
  egg 
  

   is 
  perfect 
  and 
  uninjured, 
  the 
  percentage 
  of 
  ova, 
  which 
  are 
  impregnated, 
  is 
  much 
  larger 
  

   than 
  by 
  the 
  old 
  method, 
  reaching, 
  I 
  should 
  say, 
  quite 
  90 
  per 
  cent 
  of 
  all 
  that 
  are 
  taken 
  

   when 
  the 
  products 
  are 
  perfectly 
  ripe. 
  It 
  is 
  also 
  found 
  that 
  the 
  products 
  are 
  not 
  so 
  

   readily 
  removed 
  by 
  my 
  process 
  if 
  they 
  are 
  not 
  perfectly 
  mature, 
  which 
  is 
  also 
  to 
  

   a 
  certain 
  extent 
  a 
  safeguard 
  against 
  poor 
  or 
  immature 
  spawn. 
  In 
  the 
  course 
  of 
  

   an 
  hour 
  after 
  the 
  products 
  of 
  the 
  two 
  sexes 
  have 
  been 
  mingled 
  together 
  it 
  will 
  

   be 
  found 
  that 
  nearly 
  every 
  egg 
  has 
  assumed 
  a 
  globular 
  form, 
  has 
  extruded 
  a 
  polar 
  

   cell, 
  lost 
  the 
  distinct 
  germinative 
  vesicle 
  and 
  spot 
  in 
  the 
  center, 
  and 
  begun 
  to 
  develop. 
  

  

  It 
  is 
  noteworthy 
  that 
  our 
  practice 
  as 
  herein 
  described 
  lias 
  completely 
  vindicated 
  

   the 
  statement 
  made 
  by 
  the 
  distinguished 
  French 
  anatomist 
  and 
  enibryologist, 
  M. 
  

   Lacaze-Duthiers, 
  that 
  there 
  is 
  Itut 
  a 
  single 
  generative 
  opening 
  on 
  each 
  side 
  of 
  the 
  

   visceral 
  mass 
  of 
  the 
  oyster, 
  and 
  that, 
  as 
  we 
  have«tated, 
  it 
  is 
  found 
  to 
  open 
  just 
  below 
  

   the 
  great 
  adductor 
  muscle. 
  

  

  We 
  have 
  also 
  discovered, 
  since 
  the 
  foregoing 
  was 
  written, 
  that 
  the 
  use 
  of 
  an 
  

   excessive 
  amount 
  of 
  milt 
  is 
  of 
  no 
  advantage. 
  The 
  water 
  in 
  which 
  the 
  eggs 
  are 
  to 
  be 
  

   impregnated 
  only 
  requires 
  to 
  be 
  rendered 
  slightly 
  milky; 
  a 
  very 
  few 
  drops 
  of 
  good 
  

   milt 
  is 
  sufiicient 
  to 
  make 
  the 
  impregnation 
  a 
  success. 
  Too 
  much 
  milt 
  causes 
  the 
  eggs 
  

  

  