﻿196 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  While 
  we 
  know 
  in 
  a 
  general 
  way 
  some 
  of 
  the 
  conditions 
  that 
  are 
  

   necessary 
  for 
  the 
  existence 
  of 
  certain 
  animal 
  forms, 
  it 
  is 
  strange 
  that 
  

   they 
  have 
  not 
  been 
  more 
  closely 
  studied 
  in 
  specific 
  cases 
  among 
  animals 
  

   which 
  are 
  not 
  domesticated. 
  We 
  have 
  many 
  reasons 
  for 
  the 
  belief 
  

   that 
  these 
  factors 
  are 
  often 
  excessively 
  complex, 
  and 
  hence 
  difficult 
  

   to 
  discover. 
  No 
  doubt 
  even 
  a 
  superficial 
  study, 
  however, 
  would 
  reveal 
  

   in 
  most 
  cases 
  many 
  facts 
  which 
  would 
  be 
  worth 
  knowing 
  concerning 
  

   the 
  creature's 
  relation 
  to 
  its 
  environment. 
  

  

  There 
  are 
  two 
  reasons 
  for 
  giving 
  here 
  a 
  brief 
  account 
  of 
  some 
  obser- 
  

   vations 
  upon 
  the 
  conditions 
  controlling 
  and 
  determining 
  the 
  clam's 
  

   existence. 
  These 
  few 
  observations 
  relating 
  to 
  the 
  environment, 
  though 
  

   they 
  leave 
  much 
  to 
  1)0 
  learned, 
  may 
  be 
  of 
  some 
  biological 
  interest, 
  and, 
  

   in 
  the 
  second 
  place, 
  they 
  seem 
  sufficient 
  to 
  formulate 
  a 
  plan 
  for 
  clam 
  

   culture, 
  which, 
  in 
  the 
  now 
  depleted 
  condition 
  of 
  our 
  clam 
  shores, 
  is 
  

   certainly 
  needed. 
  They 
  are 
  not 
  all 
  included 
  under 
  one 
  heading, 
  but 
  

   are 
  scattered 
  through 
  the 
  following 
  account, 
  and 
  concern 
  both 
  the 
  

   natural 
  open 
  flats 
  and 
  the 
  isolated 
  localities 
  where 
  the 
  young 
  sometimes 
  

   collect, 
  in 
  enormous 
  numbers, 
  only 
  to 
  be 
  destroyed. 
  The 
  conditions 
  

   determining 
  the 
  possibility 
  of 
  mere 
  existence, 
  as 
  well 
  as 
  those 
  which 
  

   allow 
  the 
  most 
  rapid 
  growth, 
  have 
  been 
  studied 
  more 
  carefully 
  in 
  

   artificially 
  constructed 
  beds. 
  

  

  CONDITIONS 
  OF 
  NATURAL 
  GROWTH 
  ON 
  BEACHES 
  AND 
  FLATS. 
  

  

  <:;iiarai;tp:r 
  of 
  the 
  bottom. 
  

  

  The 
  soil 
  mast 
  he 
  somewhat 
  tenacious. 
  — 
  It 
  is 
  impossible 
  for 
  clams 
  to 
  

   exist 
  where 
  there 
  is 
  much 
  shifting 
  of 
  the 
  bottom. 
  The 
  animal 
  is 
  

   buried 
  deep, 
  and 
  reaches 
  up 
  to 
  the 
  surface 
  onl}'^ 
  by 
  its 
  siphons. 
  

   When 
  foreign 
  bodies, 
  even 
  sand 
  grains 
  in 
  sufficient 
  number, 
  touch 
  the 
  

   sensory 
  tentacles 
  at 
  the 
  opening 
  of 
  the 
  incurrent 
  siphon, 
  the 
  whole 
  

   organ 
  is 
  withdrawn 
  for 
  a 
  greater 
  or 
  less 
  distance 
  into 
  the 
  burrow. 
  It 
  

   is 
  probably 
  true 
  that 
  a 
  few 
  sand 
  grains 
  coming 
  in 
  contact 
  with 
  the 
  

   ends 
  of 
  the 
  siphons 
  will 
  not 
  cause 
  their 
  retraction, 
  for 
  we 
  usually 
  find 
  

   more 
  or 
  less 
  sand 
  in 
  the 
  digestive 
  tracts 
  of 
  clams 
  which 
  live 
  on 
  sandy 
  

   flats. 
  A 
  larger 
  quantity, 
  however, 
  will 
  cause 
  a 
  withdrawal, 
  and 
  into 
  

   the 
  opening 
  thus 
  left 
  sand 
  may 
  collect 
  and, 
  settling 
  closely, 
  so 
  effectu- 
  

   ally 
  close 
  it 
  that 
  the 
  siphons 
  can 
  not 
  again 
  be 
  pushed 
  up 
  to 
  the 
  surface. 
  

   Deprived 
  of 
  the 
  food 
  and 
  oxygen-bearing 
  stream 
  of 
  water, 
  the 
  clam 
  

   (juickly 
  perishes. 
  

  

  Planting 
  experiments 
  will 
  fail 
  unless 
  great 
  care 
  is 
  exercised 
  in 
  

   selecting 
  a 
  bottom 
  which 
  does 
  not 
  shift. 
  A 
  certain 
  bank 
  on 
  a 
  large 
  

   flat 
  is 
  recalled, 
  which 
  is 
  said 
  formerly 
  to 
  have 
  yielded 
  many 
  clams. 
  

   Its 
  surface 
  showed 
  ripple 
  marks, 
  but 
  clams 
  were 
  recently 
  planted 
  on 
  

   it 
  and 
  at 
  once 
  were 
  smothered. 
  This 
  experience 
  also 
  shows 
  that 
  con- 
  

  

  