﻿EXPERIMENTS 
  IN 
  PROPAGATION 
  OF 
  FRESH-WATER 
  MUSSELS 
  OF 
  

   THE 
  QUADRULA 
  GROUP* 
  

  

  By 
  Arthur 
  Day 
  Howard, 
  

   Scientific 
  Assistant, 
  United 
  States 
  Bureau 
  of 
  Fisheries. 
  

  

  INTRODUCTION. 
  

  

  The 
  fresh-water 
  mussels 
  of 
  central 
  North 
  America 
  with 
  their 
  heavy 
  

   shells 
  of 
  beautiful 
  pearl 
  are 
  a 
  natural 
  resource 
  the 
  value 
  of 
  which 
  

   probably 
  has 
  not 
  begun 
  to 
  be 
  realized. 
  The 
  extensive 
  development 
  

   of 
  the 
  pearl-button 
  industry 
  in 
  a 
  brief 
  period 
  of 
  20 
  years 
  is 
  evidence 
  

   of 
  the 
  wealth 
  of 
  the 
  original 
  natural 
  supply; 
  but 
  a 
  very 
  evident 
  

   decrease 
  of 
  readily 
  obtainable 
  shells, 
  along 
  with 
  the 
  increasing 
  necessity 
  

   tor 
  extension 
  of 
  clamming 
  operations 
  to 
  more 
  and 
  more 
  distant 
  

   sources 
  of 
  supply, 
  has 
  made 
  it 
  evident 
  that 
  this 
  resource 
  is 
  not 
  

   unlimited. 
  

  

  Within 
  the 
  first 
  10 
  years 
  of 
  the 
  growth 
  of 
  the 
  industry, 
  interested 
  

   manufacturers 
  requested 
  an 
  investigation 
  of 
  conditions 
  by 
  the 
  

   United 
  States 
  Bureau 
  of 
  Fisheries. 
  The 
  purposes 
  of 
  this 
  first 
  investi- 
  

   gation 
  (Smith, 
  1899, 
  Simpson, 
  1899) 
  were 
  to 
  discover 
  whether 
  

   indiscriminate 
  and 
  wasteful 
  methods 
  were 
  being 
  employed 
  that 
  

   might 
  be 
  corrected 
  by 
  supervision 
  or 
  restrictive 
  legislation. 
  Later 
  

   there 
  were 
  carried 
  on 
  for 
  a 
  number 
  of 
  years 
  investigations 
  to 
  determine 
  

   if 
  methods 
  could 
  be 
  found 
  for 
  artificially 
  supplementing 
  the 
  natural 
  

   production 
  of 
  young 
  mussels, 
  i 
  e., 
  methods 
  similar 
  to 
  those 
  so 
  suc- 
  

   cessfully 
  employed 
  by 
  the 
  Bureau 
  in 
  the 
  culture 
  of 
  oysters, 
  trout, 
  

   lobsters, 
  and 
  other 
  water 
  forms 
  of 
  economic 
  importance. 
  

  

  The 
  essential 
  facts 
  in 
  the 
  hfe 
  history 
  of 
  the 
  fresh-water 
  pearl 
  

   mussels 
  (Unionidse 
  or 
  Naiades) 
  have 
  been 
  known 
  since 
  the 
  discovery 
  

   by 
  Leydig 
  in 
  1866 
  that 
  at 
  one 
  stage 
  they 
  are 
  parasitic 
  upon 
  fishes. 
  

   An 
  historical 
  account 
  of 
  these 
  discoveries 
  and 
  the 
  life 
  history 
  of 
  

   fresh-water 
  mussels, 
  together 
  with 
  methods 
  which 
  have 
  been 
  adopted 
  

   for 
  their 
  propagation, 
  have 
  been 
  described 
  in 
  pubhcations 
  by 
  the 
  

   Bureau 
  of 
  Fisheries 
  (Simpson, 
  1899, 
  Lefevre 
  and 
  Curtis, 
  1912). 
  

   The 
  work 
  in 
  propagation, 
  however, 
  has 
  been 
  limited 
  to 
  a 
  few 
  species 
  

  

  