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  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  ARTIFICIAL 
  PROPAGATION. 
  

  

  Artificial 
  propagation 
  iu 
  the 
  fish-culturist's 
  sense, 
  the 
  raising 
  of 
  

   oyster 
  fry 
  from 
  artificially 
  fertilized 
  eggs, 
  has, 
  at 
  the 
  present 
  time, 
  no 
  

   place 
  in 
  practical 
  oyster- 
  culture. 
  It 
  may 
  perhaps 
  sometime 
  demon- 
  

   strate 
  its 
  applicability 
  to 
  a 
  system 
  of 
  spat 
  production 
  in 
  small 
  closed 
  

   ponds, 
  but 
  it 
  can 
  have 
  absolutely 
  no 
  use 
  in 
  the 
  present 
  methods 
  of 
  

   oyster- 
  growing. 
  It 
  is 
  futile 
  to 
  expect 
  any 
  results 
  from 
  deposits 
  of 
  the 
  

   swimming 
  fry 
  uj^on 
  beds 
  planted 
  in 
  the 
  open 
  waters 
  of 
  the 
  bays 
  and 
  

   sounds 
  where 
  the 
  conditions 
  are 
  usually 
  such 
  as 
  would 
  bring 
  about 
  a 
  

   wide 
  distribution. 
  Fry 
  so 
  deposited 
  would 
  be, 
  no 
  doubt, 
  largely 
  carried 
  

   to 
  other 
  beds, 
  and 
  be 
  lost 
  to 
  the 
  man 
  who 
  planted 
  them, 
  or 
  else 
  would 
  

   fall 
  upon 
  unsuitable 
  bottom. 
  Their 
  fate 
  after 
  being 
  deposited 
  in 
  the 
  

   water 
  is 
  so 
  uncertain 
  that, 
  in 
  our 
  present 
  state 
  of 
  knowledge, 
  it 
  

   would 
  be 
  a 
  waste 
  of 
  eftbrt 
  for 
  either 
  Government 
  hatcheries 
  or 
  private 
  

   individuals 
  to 
  attempt 
  to 
  increase 
  the 
  oyster 
  by 
  such 
  means. 
  

  

  If, 
  however, 
  there 
  can 
  be 
  devised 
  some 
  successful 
  method 
  of 
  closed- 
  

   pond 
  production, 
  then 
  artificial 
  propagation 
  may 
  find 
  a 
  field 
  of 
  useful- 
  

   ness. 
  Dr. 
  Eyder 
  suggested 
  that 
  the 
  available 
  amount 
  of 
  fry 
  in 
  his 
  

   method 
  of 
  spat-culture 
  might 
  be 
  increased 
  by 
  adding 
  embryonized 
  

   water 
  to 
  the 
  inlet 
  to 
  the 
  sluice 
  at 
  the 
  beginning 
  of 
  flood 
  tide, 
  the 
  

   embryos 
  being 
  carried 
  up 
  through 
  the 
  cultch 
  upon 
  tlie 
  flood 
  and 
  back 
  

   again 
  ujwn 
  the 
  ebb, 
  thus 
  giving 
  a 
  double 
  chance 
  for 
  fixation. 
  There 
  

   is 
  no 
  doubt 
  but 
  that 
  the 
  proportion 
  of 
  eggs 
  successfully 
  fertilized 
  can 
  

   be 
  increased 
  by 
  the 
  artificial 
  mixture 
  of 
  the 
  ova 
  and 
  spermatozoa 
  

   according 
  to 
  methods 
  which 
  science 
  has 
  demonstrated. 
  

  

  Another 
  experiment 
  by 
  the 
  same 
  investigator 
  showed 
  that 
  spat 
  could 
  

   be 
  raised 
  in 
  a 
  practically 
  closed 
  pond 
  from 
  artificially 
  fertilized 
  eggs. 
  

   The 
  experiment 
  was 
  briefly 
  as 
  follows 
  : 
  The 
  pond 
  was 
  excavated 
  in 
  the 
  

   salt 
  marsh 
  on 
  the 
  shore 
  of 
  Chiucoteague 
  Bay. 
  It 
  was 
  about 
  20 
  feet 
  

   square 
  and 
  3J 
  feet 
  deep, 
  and 
  communicated 
  with 
  the 
  bay 
  by 
  a 
  canal 
  10 
  

   feet 
  long, 
  2 
  feet 
  wide, 
  and 
  the 
  same 
  depth 
  as 
  the 
  pond. 
  The 
  mouth 
  of 
  

   the 
  canal 
  was 
  closed 
  with 
  a 
  filter 
  composed 
  of 
  boards 
  perforated 
  with 
  

   auger-holes 
  and 
  lined 
  inside 
  with 
  gunny-cloth 
  or 
  bagging. 
  The 
  boards 
  

   constituted 
  two 
  diaphragms, 
  an 
  inner 
  and 
  outer, 
  the 
  interval 
  of 
  2 
  inches 
  

   between 
  being 
  filled 
  with 
  clean 
  sharp 
  sand. 
  Through 
  this 
  the 
  tide 
  

   ebbed 
  and 
  flowed, 
  giving 
  a 
  rise 
  and 
  fall 
  of 
  from 
  4 
  to 
  6 
  inches 
  during 
  

   the 
  interval 
  between 
  successive 
  tides. 
  

  

  This 
  filter, 
  like 
  most 
  structures 
  of 
  its 
  class, 
  showed 
  a 
  tendency 
  to 
  

   clog 
  after 
  it 
  had 
  been 
  in 
  use 
  for 
  some 
  time, 
  and 
  as, 
  from 
  its 
  shape, 
  it 
  

   was 
  difficult 
  to 
  cleanse. 
  Dr. 
  Ryder 
  devised 
  the 
  following 
  arrangement, 
  

   which 
  is 
  accessible 
  at 
  all 
  times 
  and 
  in 
  which 
  the 
  sand 
  may 
  be 
  renewed 
  

   at 
  will: 
  

  

  My 
  improved 
  permeable 
  diaphragm 
  is 
  placed 
  horizontally 
  within 
  an 
  oblong 
  

   trunk 
  or 
  box, 
  A, 
  fig. 
  1^ 
  of 
  plate 
  IV. 
  The 
  box 
  is 
  made 
  of 
  inch 
  planks, 
  to 
  which 
  strong 
  

   horizontal 
  sidepieces, 
  a, 
  figs. 
  2 
  and 
  3, 
  are 
  secured, 
  and 
  to 
  which 
  are 
  fastened 
  the 
  

  

  