﻿LOBSTER 
  AND 
  CLAM 
  INVESTIGATIONS. 
  205 
  

  

  stream 
  entering 
  the 
  mouth 
  of 
  this 
  ba}- 
  . 
  It 
  carries 
  embryos 
  which 
  it 
  

   has 
  received 
  from 
  beds 
  outside. 
  At 
  high 
  water 
  embrj^os 
  are 
  added^ 
  

   also, 
  from 
  beds 
  of 
  mature 
  clams 
  inside. 
  The 
  incoming- 
  stream 
  is 
  

   checked 
  by 
  the 
  eelgrass 
  in 
  the 
  center 
  of 
  the 
  bay. 
  Much 
  of 
  the 
  water 
  

   is 
  deflected 
  to 
  the 
  sides, 
  and 
  a 
  much 
  larger 
  quantity 
  of 
  it 
  passes 
  over 
  

   the 
  bottom 
  there 
  than 
  elsewhere. 
  That 
  is 
  to 
  say, 
  ver}- 
  many 
  more 
  

   embryos 
  are 
  borne 
  over 
  this 
  line 
  parallel 
  to 
  the 
  beach 
  than 
  anywhere 
  

   else. 
  When 
  the 
  tide 
  runs 
  out 
  it 
  takes 
  the 
  same 
  course 
  as 
  on 
  entering, 
  

   and 
  for 
  the 
  same 
  reason. 
  

  

  We 
  ma}' 
  suppose 
  that 
  for 
  several 
  weeks 
  embryos 
  are 
  continually 
  

   dropping 
  to 
  the 
  bottom, 
  losing 
  their 
  cilia, 
  and 
  attaching 
  themselves 
  

   by 
  the 
  byssus. 
  That 
  this 
  strip 
  receives 
  accessions 
  of 
  small 
  clams 
  for 
  

   several 
  weeks 
  will 
  be 
  demonstrated. 
  Evidently, 
  then, 
  many 
  more 
  

   would 
  reach 
  the 
  bottom 
  here 
  than 
  elsewhere. 
  At 
  the 
  same 
  time 
  a 
  few 
  

   would 
  fall 
  upon 
  the 
  eelgrass 
  or 
  on 
  the 
  bottom 
  on 
  which 
  it 
  grows, 
  and 
  

   some 
  would 
  also 
  find 
  lodgment 
  between 
  the 
  tide 
  lines 
  at 
  the 
  end 
  of 
  a 
  

   flood 
  and 
  the 
  beginning 
  of 
  an 
  ebb 
  tide. 
  This 
  may 
  account 
  for 
  the 
  

   distribution 
  in 
  this 
  bay, 
  and 
  in 
  similar 
  cases 
  observed 
  there 
  is 
  also 
  a 
  

   swift, 
  narrow 
  current. 
  

  

  In 
  the 
  summer 
  of 
  1899 
  this 
  set 
  of 
  small 
  clams 
  maintained 
  itself 
  for 
  

   some 
  little 
  time, 
  the 
  reason 
  being 
  that 
  sediment 
  was 
  not 
  deposited 
  

   over 
  this 
  area. 
  No 
  doubt 
  great 
  numbers 
  of 
  embryos 
  carried 
  into 
  the 
  

   wide 
  upper 
  part 
  of 
  the 
  bay 
  also 
  settled 
  to 
  the 
  bottom 
  there. 
  But 
  

   the}' 
  were 
  unable 
  to 
  establish 
  themselves 
  and 
  undoubtedly 
  perished, 
  

   because 
  the 
  slacking 
  current 
  deposited 
  silt, 
  and 
  quickly 
  smothered 
  them. 
  

   None 
  were 
  found 
  along 
  the 
  shores 
  of 
  this 
  part 
  of 
  the 
  bay. 
  This 
  soft 
  

   deposit 
  was 
  probably 
  often 
  agitated 
  by 
  unusual 
  tides, 
  or 
  even 
  by 
  rains 
  

   or 
  strong 
  winds. 
  It 
  is 
  possible 
  for 
  the 
  clams 
  to 
  live 
  only 
  where 
  a 
  

   current 
  is 
  running 
  with 
  a 
  velocit}^ 
  great 
  enough 
  to 
  prevent 
  a 
  deposit. 
  

  

  These 
  facts 
  seem 
  to 
  be 
  sufficient 
  to 
  account 
  for 
  the 
  distribution 
  and 
  

   maintenance 
  of 
  young 
  clams, 
  but 
  it 
  may 
  seem 
  strange 
  that 
  similarly 
  

   crowded 
  areas 
  were 
  not 
  found 
  more 
  often 
  when 
  a 
  search 
  was 
  made 
  for 
  

   them 
  near 
  many 
  other 
  clam 
  beds. 
  But 
  even 
  when 
  the 
  currents 
  were 
  

   favorable, 
  the 
  embryos 
  in 
  the 
  water, 
  although 
  deposited 
  in 
  the 
  same 
  

   manner, 
  may 
  have 
  been 
  so 
  few 
  in 
  number 
  as 
  to 
  escape 
  observation. 
  

  

  The 
  conditions 
  governing 
  clam 
  distribution 
  are 
  in 
  some 
  respects 
  

   similar 
  to 
  those 
  determining 
  the 
  set 
  of 
  oyster 
  spat. 
  The 
  swimming 
  

   young 
  of 
  the 
  oyster 
  fixes 
  firmly 
  to 
  foreign 
  objects. 
  Its 
  distribution 
  

   is 
  often 
  perplexing. 
  Sometimes, 
  as 
  in 
  parts 
  of 
  Long 
  Island 
  Sound, 
  

   the 
  attachment 
  takes 
  place 
  in 
  deep 
  water. 
  On 
  the 
  "coon" 
  oyster 
  

   banks 
  of 
  the 
  South 
  Carolina 
  sounds, 
  attachment 
  rarely 
  occurs 
  below 
  

   low-tide 
  mark. 
  In 
  some 
  regions 
  the 
  set 
  is 
  at 
  one 
  time 
  high, 
  at 
  another 
  

   time 
  low. 
  

  

  Several 
  suggestions 
  have 
  been 
  made 
  in 
  an 
  attempt 
  to 
  explain 
  these 
  

   peculiarities 
  of 
  distribution. 
  They 
  include 
  the 
  influence 
  of 
  varying 
  

  

  