﻿214 
  REPOET 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  on 
  July 
  4, 
  1900. 
  The 
  mean 
  of 
  this 
  series, 
  expressed 
  in 
  eighths 
  of 
  an 
  

   inch, 
  was 
  20.952, 
  or 
  nearly 
  2| 
  inches. 
  The 
  volume 
  of 
  a 
  clam 
  1| 
  inches 
  

   long- 
  is 
  4. 
  5 
  cc. 
  That 
  of 
  an 
  individual 
  2f 
  inches 
  in 
  length 
  is 
  32 
  cc. 
  Hence 
  

   the 
  increase 
  in 
  volume 
  is 
  about 
  688 
  per 
  cent. 
  

  

  RESULTS 
  OF 
  THE 
  EXPERIMENTS. 
  

  

  It 
  should 
  be 
  remembered 
  that 
  on 
  many 
  of 
  the 
  beds, 
  especially 
  upon 
  

   several 
  which 
  were 
  placed 
  near 
  the 
  upper 
  end 
  of 
  the 
  small 
  harbor 
  at 
  

   Woods 
  Hole, 
  conditions 
  of 
  growth 
  were 
  not 
  favorable. 
  About 
  the 
  

   middle 
  of 
  July 
  the 
  pebbles 
  and 
  stones 
  on 
  the 
  surface 
  were 
  coated 
  with 
  

   a 
  dense 
  growth 
  of 
  the 
  seaweed 
  Enter 
  omorpha. 
  Diatoms, 
  which 
  form 
  

   the 
  food 
  of 
  clams, 
  are 
  to 
  be 
  found 
  in 
  great 
  numbers 
  among 
  the 
  threads 
  

   of 
  this 
  alga, 
  but 
  the 
  mat 
  was 
  so 
  dense 
  that 
  it 
  must 
  have 
  interfered 
  

   seriously 
  with 
  the 
  process 
  of 
  obtaining 
  food 
  from 
  the 
  currents. 
  Great 
  

   masses 
  of 
  dead 
  eel 
  grass, 
  which 
  was 
  barely 
  floated 
  at 
  high 
  tide, 
  also 
  

   remained 
  upon 
  the 
  beds 
  for 
  days 
  at 
  a 
  time 
  during 
  the 
  summer, 
  and 
  

   must 
  have 
  interfered 
  greatly 
  with 
  the 
  food-bearing 
  currents. 
  

  

  Increase 
  utith 
  pract'ically 
  no 
  current. 
  — 
  Many 
  thousand 
  clams 
  were 
  

   placed 
  in 
  the 
  beds 
  at 
  the 
  head 
  of 
  the 
  harbor. 
  These, 
  for 
  the 
  reasons 
  

   mentioned, 
  yielded 
  the 
  smallest 
  proportionate 
  increase, 
  and 
  may 
  be 
  

   considered 
  first. 
  The 
  following 
  table 
  illustrates 
  the 
  amount 
  of 
  growth 
  

   of 
  several 
  sizes 
  on 
  the 
  poorer 
  beds: 
  

  

  1\ 
  inches 
  , 
  

   23 
  inches 
  

   2| 
  inches 
  , 
  

   '1% 
  incl 
  

   2| 
  inclies 
  

  

  Figure 
  8 
  presents 
  to 
  the 
  eye 
  the 
  increase 
  of 
  volume 
  in 
  the 
  set 
  If 
  

   inches 
  long. 
  The 
  jar 
  to 
  the 
  left 
  holds 
  75 
  individuals 
  of 
  that 
  length, 
  

   while 
  the 
  other 
  contains 
  an 
  equal 
  number 
  the 
  size 
  of 
  the 
  mean 
  after 
  

   growth 
  — 
  2| 
  inches. 
  The 
  increase 
  in 
  volume 
  is 
  347 
  per 
  cent. 
  

  

  In 
  making 
  these 
  estimates 
  of 
  growth 
  there 
  is 
  in 
  each 
  case 
  a 
  slight 
  

   inaccurac}^, 
  but 
  it 
  is 
  apparent 
  that 
  in 
  comparing 
  relatively 
  small 
  

   series, 
  or 
  even 
  large 
  series, 
  to 
  show 
  the 
  increase, 
  absolute 
  precision 
  

   in 
  all 
  the 
  details 
  of 
  the 
  calculation 
  would 
  be 
  no 
  more 
  to 
  the 
  purpose 
  

   than 
  are 
  these 
  figures. 
  For 
  if 
  a 
  similar 
  experiment 
  were 
  carried 
  on 
  

   with 
  equall}^ 
  exact 
  detail 
  in 
  a 
  region 
  where 
  conditions 
  of 
  food, 
  time 
  

   of 
  exposure, 
  etc. 
  , 
  were 
  slightly 
  different, 
  the 
  results 
  would 
  vary 
  from 
  

   those 
  obtained 
  in 
  the 
  first 
  case, 
  cind 
  we 
  can 
  not 
  determine 
  the 
  varymg 
  

   posslhilities 
  of 
  different 
  conditions 
  or 
  surroundings 
  with 
  any 
  knowledge 
  

  

  