﻿GROWTH 
  AND 
  MIGRATION 
  OF 
  FRESH- 
  WATER 
  MUSSELS. 
  21 
  

  

  DISCUSSION 
  OF 
  MIGRATION 
  DATA. 
  

  

  The 
  migration 
  results 
  came 
  as 
  a 
  surprise 
  to 
  me. 
  The 
  very 
  fact 
  

   that 
  I 
  was 
  willing 
  to 
  risk 
  specunens 
  free 
  in 
  the 
  Shoofly 
  would 
  indicate 
  

   that 
  I 
  hoped 
  to 
  make 
  some 
  kind 
  of 
  recovery; 
  but 
  to 
  go 
  back 
  and 
  find 
  

   specimens 
  by 
  the 
  score— 
  apparently 
  in 
  the 
  exact 
  spot 
  where 
  they 
  were 
  

   planted 
  — 
  was 
  not 
  to 
  be 
  expected. 
  The 
  Quadrulse 
  in 
  these 
  plantings 
  

   show 
  little 
  migration; 
  the 
  Shoofly 
  specimens 
  may 
  be 
  said 
  to 
  be 
  nearly 
  

   stationary 
  in 
  water 
  over 
  3 
  feet 
  deep. 
  Those 
  placed 
  in 
  shallow 
  water 
  

   in 
  the 
  Chikaskia 
  always 
  moved 
  until 
  water 
  2 
  to 
  3 
  feet 
  deep 
  was 
  found. 
  

   Specimens 
  found 
  on 
  shoals 
  and 
  bars 
  in 
  nature 
  are 
  there 
  by 
  chance 
  

   distribution, 
  not 
  choice, 
  although 
  breeding 
  reactions 
  may 
  cause 
  migra- 
  

   tion 
  m 
  some 
  species. 
  

  

  ECONOMIC 
  BEARING 
  OF 
  EXPERIMENTS— 
  RELATED 
  PROBLEMS. 
  

  

  Wliile 
  the 
  scientific 
  interest 
  in 
  the 
  growth 
  and 
  migration 
  problems 
  

   was 
  the 
  real 
  motive 
  that 
  prompted 
  this 
  investigation, 
  it 
  was 
  the 
  

   relation 
  of 
  the 
  problem 
  to 
  the 
  practical 
  question 
  of 
  artificial 
  propa- 
  

   gation 
  of 
  mussels 
  for 
  commercial 
  purposes 
  that 
  made 
  funds 
  available 
  

   to 
  carry 
  on 
  the 
  work. 
  That 
  the 
  results 
  will 
  be 
  of 
  service 
  as 
  prelimi- 
  

   nary 
  to 
  further 
  investigation 
  is 
  a 
  matter 
  of 
  satisfaction. 
  The 
  man 
  

   interested 
  in 
  commercial 
  propagation 
  will 
  continue 
  to 
  ask 
  the 
  ques- 
  

   tion. 
  How 
  long 
  will 
  it 
  take 
  to 
  grow 
  a 
  mussel 
  to 
  marketable 
  size? 
  

   Much 
  more 
  work 
  will 
  be 
  needed 
  to 
  get 
  at 
  all 
  the 
  facts 
  in 
  the 
  case 
  of 
  

   the 
  various 
  economic 
  species; 
  and 
  where 
  the 
  work 
  of 
  propagation 
  is 
  

   to 
  be 
  conducted 
  on 
  a 
  large 
  scale, 
  preliminary 
  experiments 
  will 
  be 
  of 
  

   value 
  in 
  testing 
  the 
  fitness 
  of 
  a 
  particular 
  region 
  for 
  commercial 
  opera- 
  

   tions. 
  Some 
  of 
  the 
  methods 
  of 
  procedure 
  have 
  been 
  indicated 
  by 
  the 
  

   series 
  of 
  experiments 
  here 
  outlmed. 
  

  

  I 
  wish 
  to 
  call 
  the 
  attention 
  of 
  the 
  field 
  students 
  of 
  the 
  Unionidse 
  

   to 
  the 
  transplanting 
  of 
  adult 
  mussels 
  from 
  the 
  Chikaskia 
  to 
  the 
  Shoo- 
  

   fly, 
  where 
  young 
  specimens 
  were 
  not 
  to 
  be 
  found, 
  yet 
  these 
  trans- 
  

   planted 
  mussels 
  averaged 
  higher 
  in 
  rate 
  of 
  growth 
  than 
  the 
  regular 
  

   Chikaskia 
  specimens. 
  If 
  the 
  Shoofly 
  is 
  so 
  favorable 
  a 
  habitat 
  for 
  

   mussels, 
  why 
  are 
  young 
  specimens 
  absent 
  from 
  the 
  beds 
  ? 
  

  

  Again, 
  notice 
  the 
  transplanting 
  of 
  over 
  a 
  hundred 
  specimens 
  from 
  

   the 
  vicinity 
  of 
  lot 
  F, 
  where 
  mussels 
  are 
  so 
  abundant, 
  to 
  lot 
  E: 
  The 
  

   transplanted 
  specimens 
  did 
  as 
  well 
  in 
  growth 
  as 
  the 
  specimens 
  that 
  

   were 
  near 
  the 
  region 
  of 
  abundant 
  mussels 
  in 
  the 
  Chikaskia. 
  This 
  

   difference 
  in 
  abundance 
  was 
  by 
  no 
  means 
  slight. 
  It 
  is 
  a 
  fact 
  that 
  in 
  

   the 
  vicmity 
  of 
  lot 
  F 
  one 
  could, 
  in 
  a 
  few 
  hours, 
  collect 
  a 
  wagonload 
  

   of 
  mussels, 
  while 
  for 
  a 
  quarter 
  of 
  a 
  mile 
  above 
  and 
  below 
  the 
  Brewer 
  

   inclosure 
  two 
  of 
  us 
  were 
  able 
  to 
  get 
  only 
  30 
  specimens 
  m 
  several 
  

   hours' 
  careful 
  collecting. 
  

  

  