﻿OYSTER 
  INDUSTRY 
  OF 
  NORTH 
  CAROLINA. 
  291 
  

  

  RATE 
  OF 
  FEEDING. 
  

  

  Some 
  experimonts 
  were 
  made 
  during 
  the 
  summers 
  of 
  1000 
  and 
  1902, 
  

   in 
  order 
  to 
  ascertain 
  the 
  rapidity 
  witli 
  which 
  a 
  Newport 
  River 
  03^ster 
  is 
  

   able 
  to 
  collect 
  the 
  amount 
  of 
  food 
  usually 
  found 
  in 
  its 
  stomach, 
  and 
  the 
  

   methods 
  and 
  results 
  of 
  these 
  experiments 
  are 
  given 
  in 
  the 
  text 
  and 
  

   tables 
  following. 
  

  

  A 
  number 
  of 
  oysters 
  were 
  tonged 
  from 
  one 
  of 
  the 
  Newport 
  River 
  

   natural 
  oyster 
  beds, 
  awd 
  individuals 
  of 
  about 
  equal 
  size 
  (about 
  3i 
  

   inches 
  in 
  length) 
  were 
  selected 
  for 
  the 
  experiments. 
  Three 
  of 
  them 
  

   were 
  immediately 
  opened 
  and 
  their 
  stomach 
  contents 
  removed 
  and 
  

   preserved. 
  The 
  others 
  were 
  taken 
  to 
  the 
  laboratory, 
  scrubbed 
  clean, 
  

   and 
  put 
  to 
  fast 
  for 
  three 
  days, 
  in 
  order 
  to 
  rid 
  them, 
  without 
  injuiy, 
  of 
  

   the 
  food 
  already 
  in 
  their 
  stomachs. 
  Twice 
  each 
  day 
  they 
  were 
  put 
  

   into 
  a 
  tub 
  tilled 
  with 
  filtered 
  sea 
  water, 
  so 
  they 
  might 
  throw 
  out 
  an}- 
  

   refuse 
  matter 
  which 
  had 
  collected 
  and 
  be 
  kept 
  in 
  a 
  healthy 
  condition. 
  

   It 
  had 
  previously 
  been 
  noted 
  that 
  digestion 
  is 
  not 
  carried 
  on 
  normally- 
  

   while 
  the 
  animals 
  are 
  out 
  of 
  the 
  water, 
  and 
  the 
  object 
  of 
  these 
  baths 
  

   was 
  mainly 
  to 
  stimulate 
  the 
  normal 
  process 
  of 
  digestion 
  and 
  to 
  rid 
  the 
  

   stomachs 
  of 
  diatoms 
  as 
  quickly 
  as 
  possible. 
  On 
  the 
  fourth 
  dav 
  three 
  

   of 
  the 
  03'sters 
  were 
  opened 
  and 
  the 
  stomach 
  contents 
  then 
  remaining 
  

   were 
  removed. 
  This 
  amount 
  was 
  made 
  the 
  l)asis 
  for 
  the 
  calculations 
  

   of 
  the 
  rate 
  of 
  feeding*. 
  The 
  remaining 
  03'sters 
  were 
  taken 
  back 
  to 
  

   their 
  home 
  feeding 
  ground 
  and 
  placed 
  in 
  the 
  water 
  near 
  a 
  stake. 
  At 
  

   convenient 
  intervals 
  they 
  were 
  taken 
  up 
  (three 
  each 
  time), 
  opened, 
  

   and 
  the 
  contents 
  of 
  their 
  stomachs 
  removed. 
  The 
  tables 
  show 
  the 
  

   dates 
  when 
  the 
  experiments 
  were 
  made 
  and 
  the 
  amount 
  of 
  food 
  found 
  

   at 
  each 
  examination 
  of 
  the 
  stomach 
  contents. 
  A 
  table 
  is 
  also 
  given 
  

   showing 
  the 
  averages 
  calculated 
  from 
  the 
  results 
  of 
  all 
  the 
  experi- 
  

   ments. 
  From 
  these 
  figures 
  it 
  appears 
  that 
  each 
  oyster 
  collected 
  385 
  

   diatoms 
  during 
  the 
  first 
  hour, 
  550 
  during 
  the 
  second, 
  1,1:06 
  during 
  the 
  

   third, 
  and 
  4,301 
  during 
  the 
  fourth. 
  This 
  increasing 
  rate 
  of 
  feeding- 
  

   is 
  probabh' 
  to 
  be 
  explained 
  as 
  due 
  to 
  gradual 
  recover}' 
  on 
  the 
  part 
  of 
  

   the 
  03'sters 
  from 
  the 
  shock 
  of 
  their 
  unusual 
  treatment 
  in 
  the 
  labora- 
  

   tory. 
  The 
  rate 
  at 
  which 
  feeding 
  took 
  place 
  during 
  the 
  fourth 
  hour 
  is 
  

   probably 
  much 
  nearer 
  the 
  rate 
  at 
  which 
  it 
  occurs 
  with 
  oysters 
  living 
  

   undisturbed 
  on 
  the 
  beds. 
  

  

  The 
  work 
  on 
  the 
  food 
  resources 
  of 
  Newport 
  River 
  shows 
  the 
  average 
  

   number 
  of 
  diatoms 
  per 
  liter 
  (or 
  about 
  a 
  quart) 
  available 
  to 
  the 
  oysters 
  

   on 
  the 
  natui-al 
  beds 
  during 
  the 
  summers 
  of 
  1900, 
  1901, 
  and 
  1902 
  to 
  be 
  . 
  

   23,432, 
  and 
  that 
  the 
  oysters 
  of 
  salable 
  size 
  examined 
  during 
  this 
  time 
  

   contained, 
  on 
  an 
  average, 
  il,453 
  diatoms. 
  If 
  the 
  usual 
  rate 
  of 
  feed- 
  

   ing 
  under 
  natural 
  conditions 
  is 
  near 
  the 
  figures 
  obtained 
  from 
  the 
  

   above 
  experiments, 
  4,301 
  diatoms 
  per 
  hour, 
  then 
  three 
  hours 
  is 
  ample 
  

   feeding 
  time 
  for 
  an 
  ovster; 
  and 
  taking 
  23,432 
  as 
  the 
  average 
  amount 
  

  

  