﻿OBSERVATIONS 
  AND 
  EXPERIMENTS 
  ON 
  THE 
  GROWTH 
  

   OF 
  OYSTERS. 
  

  

  BV 
  O. 
  C. 
  GLA8EK. 
  

  

  INTRODUCTION. 
  

  

  One 
  can 
  hardh^ 
  fail 
  to 
  be 
  impressed 
  with 
  the 
  great 
  diversitj^ 
  in 
  the 
  

   shape 
  of 
  oysters 
  on 
  the 
  natural 
  beds. 
  Normal 
  disk-shaped 
  and 
  oval 
  

   individuals 
  lie 
  side 
  bj^ 
  side 
  with 
  those 
  of 
  irregular 
  and 
  even 
  grotesque 
  

   form, 
  while 
  here 
  and 
  there 
  in 
  vertical 
  clusters 
  are 
  narrow 
  shells 
  of 
  

   extreme 
  length. 
  These 
  narrow 
  and 
  elongated 
  shells, 
  which 
  in 
  some 
  

   places 
  predominate 
  to 
  the 
  almost 
  entire 
  exclusion 
  of 
  all 
  other 
  shapes, 
  

   are 
  important 
  agents 
  in 
  the 
  formation 
  of 
  reefs, 
  marshes, 
  and 
  islands. 
  

  

  The 
  elongated 
  condition 
  of 
  these 
  03'sters 
  has 
  been 
  attributed 
  to 
  vari- 
  

   ous 
  causes. 
  According 
  to 
  one 
  view, 
  the 
  complete 
  exposure 
  to 
  the 
  air 
  

   at 
  ever}' 
  low 
  tide 
  accounts 
  for 
  it, 
  but 
  this 
  explanation 
  is 
  entirely 
  inad- 
  

   equate. 
  Not 
  onl}^ 
  is 
  it 
  difficult 
  to 
  understand 
  how 
  such 
  exposure 
  could 
  

   bring 
  about 
  the 
  great 
  increase 
  in 
  length 
  which 
  these 
  oysters 
  have 
  

   experienced 
  without 
  corresponding 
  growth 
  in 
  width, 
  but 
  it 
  completely 
  

   fails 
  to 
  account 
  for 
  the 
  fact 
  that 
  ecjually 
  elongated 
  individuals 
  are 
  

   found 
  on 
  beds 
  that 
  arc 
  alwa3^s 
  below 
  watermark 
  and 
  can 
  not 
  receive 
  

   any 
  periodic 
  exposure 
  to 
  the 
  air. 
  

  

  According 
  to 
  another 
  view, 
  this 
  shape 
  of 
  the 
  oysters 
  is 
  due 
  to 
  the 
  

   fact 
  that 
  they 
  are 
  half 
  buried 
  in 
  mud, 
  because, 
  in 
  order 
  to 
  escape 
  suf- 
  

   focation, 
  they 
  elongate 
  into 
  the 
  clearer 
  strata 
  of 
  water 
  above 
  them. 
  

   This 
  explanation 
  is 
  apparently 
  more 
  credible 
  than 
  the 
  first, 
  but 
  it 
  has 
  

   still 
  greater 
  difficulties 
  to 
  overcome. 
  If 
  the 
  presence 
  of 
  mud 
  were 
  

   the 
  factor 
  determining 
  the 
  elongation 
  of 
  oysters 
  it 
  would 
  be 
  difficult 
  

   to 
  find 
  any 
  that 
  are 
  not 
  elongated, 
  and 
  it 
  would 
  be 
  useless 
  to 
  look 
  for 
  

   well-shaped 
  oysters 
  in 
  many 
  places 
  from 
  which 
  we 
  gather 
  large 
  and 
  

   choice 
  specimens 
  for 
  the 
  market. 
  It 
  would 
  also 
  be 
  useless 
  to 
  look 
  for 
  

   elongated 
  forms 
  on 
  the 
  reefs 
  where 
  they 
  are 
  now 
  most 
  abundant, 
  

   because 
  these 
  reefs 
  are 
  almost 
  entirely 
  composed 
  of 
  shells 
  and 
  calca- 
  

   reous 
  sand. 
  That 
  there 
  is 
  nothing 
  in 
  the 
  general 
  environment 
  which 
  

   effects 
  the 
  elongation 
  of 
  03\sters 
  is 
  shown 
  further 
  by 
  the 
  fact 
  that 
  per- 
  

   fect]}- 
  normal 
  individuals 
  grow 
  on 
  the 
  elongated 
  ones. 
  

  

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