﻿[15] 
  PEARLS 
  AT 
  TAHITI 
  AND 
  TUAMOTU. 
  367 
  

  

  of 
  the 
  fecundity 
  of 
  mollusks 
  in 
  general, 
  a 
  small 
  number 
  of 
  pearl-oysters 
  

   would 
  be 
  sufficient 
  to 
  restock 
  in 
  a 
  few 
  years 
  the 
  most 
  exhausted 
  waters. 
  

   This 
  way 
  of 
  reasoning, 
  however, 
  was 
  based 
  on 
  an 
  erroneous 
  principle. 
  

   The 
  pearl-oyster 
  is 
  a 
  uni-sexual 
  mollusk, 
  either 
  entirely 
  male 
  or 
  entirely 
  

   female. 
  In 
  order 
  to 
  accomplish 
  reproduction, 
  it 
  is 
  necessary 
  that 
  withiu 
  

   a 
  certain 
  limited 
  space 
  there 
  should 
  be 
  oysters 
  of 
  both 
  sexes, 
  and 
  this 
  

   was 
  not 
  the 
  case 
  in 
  the 
  fishing 
  grounds 
  which 
  had 
  been 
  ransacked 
  more 
  

   than 
  once 
  during 
  several 
  consecutive 
  years. 
  The 
  oysters 
  were 
  too 
  scarce 
  

   and 
  too 
  isolated 
  to 
  let 
  the 
  generative 
  elements 
  meet 
  often. 
  This 
  is 
  the 
  

   sole 
  reason 
  why 
  the 
  "rahui" 
  has 
  not 
  produced 
  the 
  happy 
  results 
  which 
  

   were 
  expected 
  from 
  it. 
  Nor 
  should 
  it 
  be 
  forgotten 
  that 
  by 
  reason 
  of 
  the 
  

   relative 
  tranquillity 
  of 
  the 
  waters 
  of 
  the 
  lagoons, 
  and 
  also 
  from 
  ana- 
  

   tomical 
  reasons, 
  the 
  generative 
  elements 
  have 
  very 
  little 
  chance 
  of 
  com- 
  

   ing 
  in 
  contact 
  with 
  each 
  other. 
  I 
  have 
  often 
  found 
  that 
  the 
  spawn 
  does 
  

   not 
  go 
  far 
  from 
  the 
  place 
  where 
  it 
  was 
  produced. 
  Thus 
  the 
  branches 
  

   of 
  coral 
  near 
  conglomerations 
  of 
  oysters 
  are 
  sometimes 
  so 
  full 
  of 
  small 
  

   oysters 
  that 
  they 
  literally 
  choke 
  each 
  other. 
  This 
  is 
  a 
  fortunate 
  cir- 
  

   cumstance, 
  owing 
  to 
  which 
  it 
  becomes 
  easy 
  to 
  get 
  the 
  spawn 
  of 
  the 
  pearl- 
  

   oyster, 
  and 
  by 
  its 
  means 
  to 
  accomplish 
  their 
  production 
  in 
  the 
  lagoons 
  

   of 
  Tuamotu. 
  

  

  NATURAL 
  HISTORY. 
  

  

  Reproduction. 
  — 
  Although 
  of 
  a 
  different 
  kind, 
  the 
  pearl-oyster 
  is 
  not 
  

   excelled 
  in 
  fecundity 
  by 
  the 
  edible 
  oysters 
  raised 
  in 
  the 
  oyster-pares 
  on 
  

   the 
  coast 
  of 
  France, 
  and 
  not 
  even 
  by 
  the 
  Portuguese 
  oyster, 
  which 
  every 
  

   year 
  ejects 
  several 
  millions 
  of 
  eggs. 
  The 
  mode 
  of 
  reproduction 
  of 
  the 
  

   pearl-oyster 
  resembles 
  that 
  of 
  the 
  Portuguese 
  oyster. 
  The 
  sexual 
  pro- 
  

   ducts 
  are, 
  at 
  the 
  period 
  of 
  maturity, 
  ejected 
  from 
  the 
  genital 
  glands, 
  

   and 
  meet 
  in 
  the 
  water. 
  I 
  have 
  never 
  succeeded 
  in 
  finding 
  spawn 
  iu 
  

   the 
  valves 
  of 
  the 
  pearl-oyster, 
  although 
  I 
  have 
  opened 
  them 
  at 
  every 
  

   stage 
  of 
  the 
  reproductive 
  period. 
  

  

  Eesembling 
  the 
  trees 
  of 
  this 
  climate, 
  which 
  never 
  cease 
  to 
  bear 
  fruit 
  

   from 
  one 
  end 
  of 
  the 
  year 
  to 
  the 
  other, 
  the 
  pearl-oysters 
  seem 
  capable 
  of 
  

   performing 
  the 
  generative 
  functions 
  at 
  every 
  season 
  of 
  the 
  year. 
  I 
  have 
  

   not 
  been 
  able 
  to 
  ascertain 
  the 
  number 
  of 
  times 
  which 
  the 
  pearl-oyster 
  

   spawned 
  within 
  the 
  period 
  of 
  one 
  year, 
  but 
  they 
  certainly 
  must 
  be 
  very 
  

   numerous. 
  It 
  is 
  very 
  rare 
  to 
  find 
  the 
  sexual 
  glands 
  completely 
  empty 
  

   during 
  several 
  consecutive 
  weeks, 
  and 
  it 
  is 
  probable 
  that 
  there 
  are 
  pe- 
  

   riods 
  during 
  which 
  the 
  emissions 
  are 
  more 
  abundant 
  than 
  at 
  other 
  times. 
  

   Spawning 
  does 
  not 
  take 
  place 
  at 
  one 
  and 
  the 
  same 
  time 
  in 
  all 
  the 
  islands 
  

   of 
  the 
  archipelago, 
  nor 
  even 
  in 
  islands 
  of 
  one 
  and 
  the 
  same 
  neighbor- 
  

   hood. 
  About 
  the 
  middle 
  of 
  July 
  of 
  last 
  year 
  the 
  oysters 
  of 
  Aratica 
  

   were 
  not 
  in 
  a 
  fit 
  condition 
  for 
  reproduction, 
  while 
  at 
  this 
  very 
  time 
  the 
  

   oysters 
  of 
  Fakarava 
  ejected 
  their 
  eggs, 
  and 
  it 
  should 
  be 
  remembered 
  

   that 
  the 
  islands 
  of 
  Fakarava 
  and 
  Aratica 
  are 
  not 
  very 
  distant 
  from 
  each 
  

   other. 
  The 
  climatic 
  conditions 
  are 
  the 
  same, 
  and 
  the 
  density 
  and 
  tern- 
  

  

  