﻿[7] 
  A 
  SYSTEM 
  OF 
  OYSTER 
  CULTURE. 
  387 
  

  

  bility 
  has 
  been 
  so 
  . 
  thoroughly 
  tested 
  by 
  Mr. 
  Eowe. 
  Where 
  the 
  tide 
  

   rises 
  and 
  recedes 
  from 
  natural 
  banks, 
  thousands 
  of 
  the 
  animals 
  are 
  

   often 
  exposed 
  for 
  several 
  hours 
  during 
  low 
  tide 
  without 
  apparent 
  in- 
  

   jury. 
  The 
  animals, 
  under 
  such 
  circumstances, 
  when 
  the 
  tide 
  recedes 
  

   apparently 
  retain 
  sufficient 
  sea-water 
  between 
  their 
  valves 
  to 
  meet 
  the 
  

   demands 
  of 
  respiration 
  during 
  the 
  time 
  they 
  are 
  uncovered. 
  

  

  9. 
  Horizontal 
  distribution. 
  — 
  Their 
  range 
  of 
  distribution 
  along 
  the 
  east- 
  

   ern 
  coast 
  of 
  the 
  United 
  States 
  is 
  from 
  Damariscotta 
  Bay 
  in 
  Maine 
  south 
  

   to 
  Florida 
  and 
  the 
  Gulf 
  of 
  Mexico. 
  The 
  most 
  important 
  beds 
  indus- 
  

   trially 
  are 
  those 
  of 
  Long 
  Island 
  Sound, 
  Ghincoteague, 
  Delaware, 
  and 
  

   Chesapeake 
  Bays, 
  and 
  their 
  tributaries. 
  The 
  States 
  of 
  Maryland 
  and 
  

   Virginia 
  possess 
  the 
  greatest 
  area 
  of 
  natural 
  beds, 
  though 
  the 
  impor- 
  

   tance 
  of 
  the 
  still 
  more 
  southern 
  beds 
  is 
  probably 
  not 
  yet 
  fully 
  appre- 
  

   ciated. 
  

  

  10. 
  Influence 
  of 
  temperature. 
  — 
  The 
  temperature 
  of 
  the 
  water 
  in 
  which 
  

   the 
  oyster 
  ordinarily 
  exists 
  throughout 
  the 
  year 
  ranges 
  from 
  something 
  

   under 
  32° 
  to 
  90° 
  Fahrenheit. 
  On 
  the 
  exposed 
  banks 
  in 
  shallow 
  water 
  

   many 
  are 
  frozen 
  during 
  the 
  winter, 
  and 
  it 
  appears 
  that 
  if 
  they 
  thaw 
  out 
  

   slowly, 
  freezing 
  does 
  not 
  usually 
  injure 
  them. 
  

  

  In 
  summer, 
  or 
  during 
  the 
  spawniug 
  season, 
  the 
  temperature 
  of 
  the 
  

   water 
  ranges 
  from 
  about 
  60° 
  Fahrenheit 
  to 
  90° 
  Fahrenheit. 
  The 
  usual 
  

   temperature, 
  however, 
  is 
  from 
  60° 
  to 
  81° 
  Fahrenheit. 
  When 
  the 
  tem- 
  

   perature 
  falls 
  below 
  65° 
  Fahrenheit 
  the 
  development 
  of 
  the 
  embryos 
  is 
  

   greatly 
  impeded, 
  in 
  fact, 
  it 
  almost 
  ceases; 
  whereas, 
  at 
  a 
  temperature 
  

   ranging 
  from 
  74° 
  Fahrenheit 
  to 
  80° 
  Fahrenheit 
  it 
  is 
  very 
  rapid, 
  so 
  that 
  

   in 
  three 
  to 
  ten 
  hours 
  from 
  the 
  time 
  of 
  the 
  fertilization 
  of 
  the 
  eggs 
  they 
  

   have 
  advanced 
  as 
  far 
  as 
  the 
  swimming 
  or 
  veliger 
  stage, 
  and 
  have 
  ac- 
  

   quired 
  a 
  larval 
  shell. 
  Cold 
  rains 
  frequently 
  kill 
  a 
  great 
  deal 
  of 
  fry 
  dur- 
  

   ing 
  the 
  summer. 
  Other 
  meteorological 
  disturbances, 
  such 
  as 
  violent 
  

   thunder-storms, 
  have 
  also 
  been 
  found 
  to 
  be 
  injurious 
  or 
  fatal 
  to 
  young 
  

   oyster 
  embryos. 
  The 
  fifth 
  principle 
  to 
  be 
  borne 
  in 
  mind 
  in 
  successful 
  

   oyster 
  culture 
  is, 
  therefore, 
  the 
  following 
  : 
  That 
  the 
  prevalent 
  temperature 
  

   of 
  the 
  water 
  during 
  the 
  spawning 
  season 
  shall 
  range 
  from 
  about 
  68° 
  to 
  80° 
  

   Fahrenheit. 
  

  

  11. 
  Food 
  of 
  the 
  fry 
  and 
  spat.— 
  The 
  food 
  of 
  the 
  fry, 
  £pat, 
  and 
  adult 
  

   stages 
  of 
  the 
  oyster 
  is 
  also 
  au 
  important 
  matter. 
  That 
  of 
  the 
  fry 
  con- 
  

   sists 
  of 
  the 
  most 
  minute 
  organic 
  life 
  to 
  be 
  found 
  in 
  sea-water, 
  such 
  as 
  

   Bacteria 
  and 
  Monads. 
  Many 
  of 
  the 
  food 
  balls 
  found 
  in 
  the 
  intestine 
  of 
  

   the 
  recently 
  attached 
  spat 
  will 
  measure 
  under 
  T 
  oTrooth 
  of 
  an 
  inch 
  in 
  

   diameter. 
  The 
  cavity 
  of 
  the 
  little 
  creature's 
  stomach 
  measures 
  only 
  

   asV^th 
  of 
  an 
  inch. 
  Yet 
  in 
  this 
  minute 
  digestive 
  cavity 
  the 
  food 
  is 
  ac- 
  

   tually 
  found 
  rotating 
  in 
  the 
  form 
  of 
  minute 
  rounded 
  and 
  oval 
  bodies, 
  

   which 
  are 
  kept 
  in 
  motion 
  by 
  the 
  action 
  of 
  the 
  cilia 
  which 
  line 
  the 
  stom- 
  

   ach. 
  That 
  these 
  bodies 
  must 
  have 
  been 
  of 
  about 
  the 
  size 
  noted 
  when 
  

   they 
  were 
  originally 
  swallowed 
  and 
  as 
  seen 
  rotating 
  in 
  the 
  stomach, 
  is 
  

  

  