﻿OYSTERS 
  AND 
  METHODS 
  OF 
  OYSTER-CULTURE. 
  333 
  

  

  organic 
  matter, 
  and 
  thus 
  interfere 
  greatly 
  with 
  the 
  life 
  and 
  healthy 
  development 
  of 
  

   the 
  emhryos. 
  

  

  By 
  our 
  method 
  the 
  objectionable 
  features 
  of 
  the 
  old 
  plan, 
  as 
  stated 
  above, 
  are 
  

   overcome. 
  If 
  possible 
  select 
  good-sized 
  oysters; 
  open 
  them 
  witli 
  the 
  greatest 
  possi- 
  

   ble 
  care 
  so 
  as 
  not 
  to 
  mutilate 
  the 
  mautlo 
  and 
  soft 
  parts. 
  Carefully 
  insert 
  an 
  oyster 
  

   knife 
  betAveen 
  the 
  etlges 
  of 
  the 
  valves 
  and 
  cut 
  the 
  great 
  adductor 
  muscle 
  as 
  close 
  as 
  

   possible 
  to 
  the 
  valve 
  which 
  you 
  intend 
  to 
  remove, 
  leaving 
  the 
  animal 
  attached 
  to 
  

   the 
  other 
  valve, 
  which, 
  if 
  possible, 
  should 
  be 
  the 
  left 
  or 
  deepest 
  one. 
  The 
  soft 
  parts 
  

   being 
  firmly 
  fixed 
  or 
  held 
  fast 
  by 
  the 
  great 
  adductor 
  muscle 
  to 
  the 
  left 
  valve 
  pre- 
  

   vents 
  the 
  animal 
  from 
  slipping 
  under 
  the 
  end 
  of 
  the 
  pipette, 
  held 
  flatwise, 
  as 
  it 
  is 
  

   gently 
  and 
  firmly 
  stroked 
  over 
  the 
  generative 
  gland 
  and 
  ducts 
  to 
  force 
  out 
  the 
  

   generative 
  products. 
  

  

  To 
  prepare 
  the 
  animals 
  to 
  take 
  the 
  spawn 
  from 
  them 
  after 
  opening, 
  the 
  following 
  

   precautions 
  are 
  to 
  be 
  observed 
  : 
  Note 
  that 
  the 
  reproductive 
  gland 
  in 
  great 
  part 
  

   envelops 
  the 
  visceral 
  mass 
  and 
  extends 
  from 
  the 
  heart 
  space, 
  just 
  in 
  front 
  of 
  the 
  

   great 
  adductor, 
  to 
  within 
  a 
  half 
  inch 
  or 
  so 
  of 
  the 
  head 
  or 
  mouth 
  end 
  of 
  the 
  animal, 
  

   which 
  lies 
  next 
  to 
  the 
  hinge. 
  Note 
  also 
  that 
  both 
  sides 
  of 
  the 
  visceral 
  mass 
  which 
  

   incloses 
  the 
  stomach, 
  liver, 
  and 
  intestine 
  are 
  enveloped 
  on 
  either 
  side 
  by 
  a 
  membrane 
  

   which 
  also 
  lies 
  just 
  next 
  the 
  shell 
  and 
  is 
  garnished 
  by 
  a 
  fringe 
  of 
  purplish, 
  sensitive 
  

   tentacles 
  along 
  its 
  entire 
  border 
  except 
  at 
  the 
  head 
  end, 
  where 
  the 
  mantle 
  of 
  the 
  left 
  

   side 
  passes 
  into 
  and 
  is 
  continuous 
  with 
  that 
  of 
  the 
  right 
  side 
  of 
  the 
  animal. 
  The 
  

   ventral 
  or 
  lowermost 
  side 
  of 
  the 
  animal, 
  anatomically 
  speaking, 
  is 
  marked 
  by 
  the 
  

   four 
  closely 
  corrugated 
  gill 
  plates 
  or 
  pouches, 
  which 
  are 
  preceded 
  in 
  front 
  by 
  the 
  

   four 
  palps 
  or 
  lips, 
  but 
  both 
  the 
  gills 
  and 
  palps 
  depend 
  downward 
  between 
  the 
  lower 
  

   borders 
  of 
  the 
  mantle 
  of 
  the 
  right 
  and 
  left 
  sides. 
  Note, 
  too, 
  that 
  if 
  the 
  mantle 
  is 
  

   carefully 
  cut 
  and 
  thrown 
  back 
  on 
  the 
  exposed 
  side 
  of 
  the 
  animal 
  between 
  the 
  upper 
  

   edges 
  of 
  the 
  gills 
  and 
  the 
  lower 
  edge 
  of 
  the 
  cut 
  or 
  exposed 
  end 
  of 
  the 
  great 
  adductor 
  

   muscle, 
  the 
  lower 
  and 
  hinder 
  blunted 
  end 
  of 
  the 
  visceral 
  mass 
  will 
  be 
  exposed 
  to 
  

   view. 
  It 
  is 
  on 
  either 
  side 
  of 
  this 
  blunted 
  end 
  of 
  the 
  visceral 
  mass 
  between 
  the 
  upper 
  

   edge 
  of 
  the 
  gills 
  and 
  lower 
  side 
  of 
  the 
  great 
  muscle 
  that 
  the 
  reproductive 
  glands 
  

   open 
  almost 
  exactly 
  below 
  the 
  great 
  adductor. 
  From 
  these 
  openings 
  we 
  will 
  after- 
  

   wards 
  find, 
  if 
  the 
  animal 
  is 
  sexually 
  mature 
  and 
  the 
  operation 
  is 
  properly 
  conducted, 
  

   that 
  the 
  spawn 
  will 
  be 
  forced 
  out 
  in 
  a 
  vermicular, 
  creamy 
  white 
  stream. 
  But 
  in 
  

   order 
  to 
  fully 
  expose 
  the 
  reproductive 
  organ 
  we 
  should 
  carefully 
  continue 
  to 
  sever 
  

   the 
  mantle 
  of 
  one 
  side 
  with 
  a 
  sharp 
  penknife 
  or 
  small 
  scissors 
  some 
  distance 
  forward 
  

   of 
  the 
  great 
  muscle 
  toward 
  the 
  head, 
  cutting 
  through 
  the 
  mantle 
  just 
  above 
  the 
  

   upper 
  borders 
  of 
  the 
  gills 
  and 
  following 
  a 
  cavity 
  which 
  lies 
  between 
  the 
  latter 
  and 
  

   the 
  lower 
  border 
  of 
  the 
  visceral 
  mass. 
  

  

  A 
  little 
  experience 
  will 
  teach 
  one 
  how 
  far 
  it 
  is 
  necessary 
  to 
  carry 
  this 
  incision 
  of 
  

   the 
  mantle. 
  For 
  some 
  distance 
  in 
  front 
  of 
  the 
  heart 
  space 
  the 
  mantle 
  is 
  free 
  or 
  

   detached 
  from 
  the 
  visceral 
  mass 
  and 
  reproductive 
  organ, 
  which 
  lies 
  immediately 
  

   beneath, 
  and 
  this 
  enables 
  one, 
  if 
  the 
  last-described 
  incision 
  has 
  been 
  properly 
  made, 
  

   to 
  almost 
  completely 
  expose 
  the 
  one 
  side 
  of 
  the 
  visceral 
  mass 
  and 
  the 
  richly 
  tinted, 
  

   yellowish-white 
  reproductive 
  gland 
  which 
  constitutes 
  its 
  superficial 
  portion. 
  The 
  

   opening 
  of 
  the 
  gland 
  and 
  its 
  superficial 
  ramifying 
  ducts 
  being 
  laid 
  bare 
  on 
  the 
  

   exposed 
  side 
  of 
  the 
  animal, 
  we 
  are 
  ready 
  to 
  press 
  out 
  the 
  spawn 
  on 
  that 
  side. 
  Before 
  

   beginning 
  this, 
  however, 
  it 
  is 
  important 
  to 
  observe 
  that 
  the 
  principal 
  duct 
  passes 
  

   down 
  just 
  along 
  the 
  edge 
  of 
  the 
  visceral 
  mass 
  where 
  the 
  latter 
  l)Ounds 
  the 
  heart 
  

   space, 
  in 
  which 
  the 
  heart 
  may 
  be 
  observed 
  to 
  slowly 
  pulsate, 
  and 
  that 
  this 
  great 
  duct 
  

   ends 
  somewhere 
  on 
  the 
  surface 
  of 
  the 
  ventral 
  blunted 
  end 
  of 
  the 
  visceral 
  mass 
  (plate 
  i, 
  

   fig. 
  2 
  d). 
  To 
  expose 
  the 
  great 
  or 
  main 
  generative 
  duct 
  it 
  may 
  be 
  necessary 
  to 
  cut 
  

   through 
  or 
  remove 
  the 
  pericardial 
  membrane 
  which 
  incloses 
  or 
  covers 
  the 
  heart 
  space 
  

   on 
  the 
  exposed 
  side. 
  If 
  the 
  oyster 
  is 
  sexually 
  mature, 
  the 
  main 
  duct 
  will 
  be 
  observed 
  

   to 
  be 
  distended 
  with 
  spawn, 
  and 
  that, 
  originating 
  from 
  it 
  and 
  branching 
  out 
  over 
  

   almost 
  the 
  entire 
  surface 
  of 
  the 
  visceral 
  mass, 
  there 
  are 
  minor 
  ducts 
  given 
  off, 
  which 
  

  

  