﻿372 
  EEPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [20] 
  

  

  in 
  several 
  places, 
  compelling 
  the 
  animal 
  by 
  a 
  constant 
  work 
  of 
  secretion 
  

   to 
  close 
  up 
  the 
  numerous 
  holes 
  which 
  have 
  been 
  bored 
  in 
  the 
  shell; 
  the 
  

   second 
  confines 
  itself 
  to 
  lodgiug 
  in 
  the 
  thick 
  part 
  of 
  the 
  shell, 
  just 
  as 
  

   similar 
  shell-fish 
  on 
  the 
  coast 
  of 
  France 
  lodge 
  in 
  stones 
  or 
  rocks. 
  These 
  

   animals 
  are 
  aided 
  in 
  their 
  work 
  of 
  perforation 
  by 
  marine 
  worms, 
  one 
  of 
  

   which 
  (called 
  the 
  "needle- 
  worm," 
  the 
  most 
  injurious 
  of 
  all) 
  bores 
  numer- 
  

   ous 
  holes 
  and 
  small 
  galleries 
  between 
  the 
  outer 
  layer 
  of 
  the 
  shell 
  and 
  

   the 
  mother-of-pearl 
  part, 
  causing 
  it 
  to 
  resemble 
  a 
  piece 
  of 
  wood 
  attacked 
  

   by 
  xylophagous 
  animals. 
  Mother-of-pearl 
  thus 
  deteriorated 
  loses 
  all 
  

   commercial 
  value, 
  and 
  is 
  called 
  perforated 
  or 
  worm-eaten 
  mother-of-pearl. 
  

   A 
  small 
  parasitic 
  sponge 
  works 
  similar 
  injury. 
  Even 
  the 
  malicious 
  crab 
  

   thinks 
  that 
  it 
  has 
  a 
  special 
  claim 
  on 
  the 
  pearl-oyster, 
  and 
  attacks 
  espe- 
  

   cially 
  the 
  young 
  ones. 
  I 
  must 
  finally 
  mention 
  the 
  polyps, 
  the 
  ascidians, 
  

   and 
  the 
  Serpula, 
  which 
  are 
  dangerous 
  parasites 
  ; 
  also 
  a 
  small 
  crab 
  called 
  

   u 
  pinnothere," 
  similar 
  to 
  the 
  one 
  found 
  in 
  France 
  in 
  non-cultivated 
  mus- 
  

   sels, 
  which 
  lodges 
  in 
  side 
  the 
  shell 
  and 
  lives 
  at 
  the 
  expense 
  of 
  the 
  oyster. 
  

   Oyster 
  culture 
  based 
  on 
  the 
  system 
  of 
  raising 
  the 
  oysters 
  in 
  boxes, 
  pro- 
  

   vides 
  protection 
  for 
  the 
  young 
  oysters 
  against 
  the 
  many 
  different 
  ene- 
  

   mies, 
  of 
  which 
  1 
  have 
  enumerated 
  only 
  a 
  few. 
  

  

  It 
  has 
  been 
  noticed 
  that 
  the 
  edible 
  oysters 
  raised 
  in 
  oyster-boxes 
  were 
  

   those 
  whose 
  shell 
  was 
  the 
  finest, 
  the 
  healthiest, 
  and 
  the 
  most 
  trans- 
  

   parent. 
  The 
  reason 
  of 
  it 
  is 
  this, 
  that 
  the 
  apparatus 
  in 
  which 
  they 
  are 
  

   inclosed, 
  rests 
  on 
  feet, 
  keeping 
  them 
  8 
  to 
  12 
  inches 
  above 
  the 
  ground. 
  

   In 
  this 
  way 
  the 
  oysters 
  are 
  no 
  longer 
  in 
  contact 
  with 
  the 
  sand 
  on 
  the 
  

   bottom 
  of 
  the 
  sea 
  where 
  those 
  animals 
  live 
  which 
  it 
  is 
  important 
  for 
  

   them 
  to 
  avoid. 
  Moreover 
  it 
  is 
  one 
  of 
  the 
  rules 
  of 
  oyster 
  culture 
  not 
  to 
  

   give 
  the 
  parasites 
  contained 
  in 
  the 
  sediments 
  which 
  engender 
  them 
  the 
  

   time 
  to 
  develop 
  and 
  become 
  fixed. 
  

  

  Coloring 
  of 
  mother-of-pearl. 
  — 
  White 
  mother-of-pearl 
  is 
  at 
  present 
  most 
  

   expensive 
  and 
  most 
  sought 
  after. 
  How 
  does 
  it 
  come 
  that 
  mollusks 
  of 
  

   the 
  same 
  kind 
  sometimes 
  have 
  a 
  white 
  shell, 
  like 
  the 
  Macassar 
  mother- 
  

   of-pearl, 
  and 
  sometimes 
  a 
  shell 
  with 
  a 
  black 
  border 
  like 
  the 
  Tahiti 
  

   mother-of-pearl? 
  Is 
  it 
  a 
  question 
  of 
  breed, 
  or 
  must 
  these 
  differences 
  of 
  

   color 
  be 
  attributed 
  to 
  more 
  or 
  less 
  local 
  influences, 
  orginating 
  from 
  the 
  

   nature 
  of 
  the 
  water 
  and 
  the 
  bottom 
  ? 
  I 
  am 
  inclined 
  to 
  the 
  latter 
  opin- 
  

   ion. 
  It 
  has 
  been 
  observed 
  in 
  France 
  that 
  the 
  element 
  in 
  which 
  shell-fish 
  

   live 
  exercises 
  an 
  influence 
  on 
  their 
  quality 
  and 
  their 
  color. 
  If, 
  for 
  in- 
  

   stance, 
  an 
  Arcachon 
  oyster, 
  one 
  year 
  old, 
  is 
  transported 
  to 
  the 
  pares 
  in 
  

   the 
  river 
  Belon 
  in 
  the 
  Department 
  of 
  Finistere, 
  it 
  will 
  be 
  noticed 
  that 
  

   after 
  a 
  while 
  that 
  part 
  of 
  the 
  shell 
  which 
  has 
  grown 
  in 
  the 
  new 
  place 
  will 
  

   differ 
  in 
  color, 
  hardness, 
  and 
  transparency 
  from 
  the 
  original 
  part 
  of 
  the 
  

   same 
  shell. 
  Oyster 
  cultivators 
  have 
  daily 
  occasion 
  to 
  observe 
  facts 
  of 
  

   this 
  kind. 
  White 
  mother-of-pearl 
  is 
  not 
  entirely 
  unknown 
  in 
  Tahiti. 
  

   From 
  time 
  to 
  time 
  specimens 
  of 
  this 
  kind 
  are 
  found 
  in 
  the 
  lagoons 
  of 
  

   the 
  Gambier 
  Islands. 
  

  

  As 
  this 
  question 
  is 
  a 
  very 
  important 
  one 
  from 
  a 
  commercial 
  stand- 
  

  

  