﻿[9 
  I 
  A 
  SYSTEM 
  OF 
  OYSTER 
  CULTURE. 
  389 
  

  

  point 
  of 
  the 
  shore, 
  and 
  if, 
  under 
  these 
  circumstances, 
  the 
  water 
  be 
  well 
  

   charged 
  with 
  floating 
  fry 
  from 
  adult 
  oysters 
  in 
  the 
  vicinity, 
  the 
  set 
  of 
  

   sp;it 
  will 
  often 
  be 
  very 
  abundant. 
  This 
  is 
  especially 
  the 
  case 
  where 
  the 
  

   tidal 
  currents 
  are 
  strong 
  enough 
  to 
  make 
  such 
  points 
  act 
  as 
  jetties 
  

   and 
  keep 
  the 
  sediment 
  and 
  debris 
  from 
  lodging 
  on 
  the 
  cultch 
  so 
  as 
  to 
  

   cover 
  it 
  up. 
  Such 
  natural 
  conditions 
  are 
  presented 
  by 
  projecting 
  grav- 
  

   elly 
  points 
  along 
  the 
  shore 
  and 
  on 
  the 
  buoys 
  in 
  the 
  channel 
  near 
  Co- 
  

   hasset, 
  Mass. 
  So 
  constantly 
  has 
  it 
  been 
  found 
  that 
  oyster-spat 
  catches 
  

   or 
  falls 
  in 
  abundance 
  on 
  the 
  gravel 
  at 
  that 
  place 
  that 
  oystermen 
  

   were 
  formerly 
  in 
  the 
  habit 
  of 
  going 
  there 
  to 
  obtain 
  the 
  gravel 
  after 
  it 
  

   was 
  covered 
  with 
  spat 
  for 
  seeding 
  purposes. 
  We 
  actually 
  behold 
  here 
  

   in 
  operation, 
  under 
  natural 
  conditions, 
  processes 
  which 
  can 
  be 
  imitated 
  

   on 
  a 
  large 
  scale 
  by 
  artificial 
  means, 
  with 
  such 
  success 
  as 
  to 
  make 
  us 
  

   wonder 
  why 
  some 
  such 
  method 
  as 
  the 
  one 
  presently 
  to 
  be 
  proposed 
  

   was 
  never 
  applied 
  before. 
  

  

  16. 
  Effect 
  of 
  currents 
  on 
  fixation. 
  — 
  It 
  may 
  be 
  asked, 
  however, 
  will 
  the 
  

   young 
  fry 
  attach 
  itself 
  to 
  a 
  fixed 
  collecting 
  apparatus 
  where 
  the 
  current 
  

   of 
  water 
  is 
  running 
  rapidly 
  through 
  the 
  latter 
  ? 
  it 
  might 
  be 
  supposed 
  

   that 
  where 
  a 
  rapid 
  current 
  was 
  sweeping 
  over 
  the 
  cultch 
  it 
  would 
  

   have 
  no 
  chance 
  to 
  become 
  affixed, 
  but 
  this 
  is 
  a 
  mistake, 
  for 
  I 
  have 
  found 
  

   that 
  spat 
  will 
  become 
  affixed 
  to 
  a 
  stationary 
  object 
  just 
  as 
  abundantly 
  

   in 
  a 
  current 
  running 
  several 
  miles 
  an 
  hour 
  as 
  when 
  the 
  water 
  is 
  com- 
  

   paratively 
  quiescent. 
  This 
  was 
  also 
  verified 
  in 
  the 
  closed-circuit 
  experi- 
  

   ments 
  made 
  in 
  1882, 
  when 
  the 
  artificially 
  fertilized 
  embryos 
  were 
  kept 
  

   in 
  constant 
  motion. 
  Similar 
  results 
  were, 
  1 
  believe, 
  obtained 
  by 
  Brooks 
  

   and 
  Winslow 
  in 
  another 
  apparatus, 
  in 
  which 
  the 
  water 
  charged 
  with 
  

   embryos 
  was 
  kept 
  continually 
  moving. 
  All 
  of 
  the 
  facts, 
  therefore, 
  which 
  

   have 
  been 
  observed 
  both 
  under 
  natural 
  and 
  under 
  artificial 
  conditions, 
  

   indicate 
  that 
  rapid 
  movement 
  of 
  the 
  water 
  which 
  is 
  charged 
  with 
  em- 
  

   bryos 
  does 
  actually 
  in 
  no 
  way 
  interfere 
  with 
  the 
  fixation 
  of 
  the 
  fry 
  ; 
  on 
  

   the 
  contrary, 
  it 
  rather 
  seems 
  to 
  favor 
  fixation. 
  

  

  Currents 
  of 
  comparative 
  rapidity 
  and 
  force 
  do 
  not 
  detach 
  the 
  quite 
  

   recently 
  affixed 
  fry, 
  as 
  has 
  been 
  shown 
  by 
  me 
  as 
  the 
  result 
  of 
  other 
  di- 
  ' 
  

   reet 
  experiments 
  and 
  observations. 
  

  

  17. 
  Utility 
  of 
  artificial 
  fertilization. 
  — 
  The 
  artificial 
  fertilization 
  of 
  the 
  

   eggs 
  may 
  also 
  be 
  expeditiously 
  accomplished 
  with 
  certainty 
  to 
  the 
  num- 
  

   ber 
  of 
  billions 
  at 
  a 
  time, 
  so 
  that, 
  besides 
  the 
  chances 
  for 
  obtaining 
  spat 
  

   from 
  water 
  charged 
  with 
  embryos 
  by 
  natural 
  means, 
  we 
  are 
  enabled 
  to 
  

   add 
  greatly 
  in 
  favorable 
  weather 
  to 
  the 
  number 
  already 
  in 
  the 
  water. 
  

   The 
  chances 
  to 
  obtain 
  spat 
  may 
  thus 
  be 
  doubled 
  or 
  even 
  quadrupled 
  by 
  

   the 
  aid 
  of 
  artificial 
  methods. 
  

  

  18. 
  Causes 
  destructive 
  of 
  embryos. 
  — 
  Great 
  losses 
  of 
  embryos 
  are 
  d 
  oubtless 
  

   sustained 
  under 
  natural 
  conditions 
  from 
  the 
  circumstance 
  that 
  millions 
  

   of 
  billions 
  of 
  eggs 
  and 
  embryos 
  either 
  sink 
  into 
  the 
  mud 
  to 
  be 
  irrecov- 
  

   erably 
  lost, 
  or 
  many 
  ova 
  are 
  never 
  even 
  impregnated. 
  Under 
  artificial 
  

   conditions 
  these 
  embryos 
  may 
  be 
  reared 
  to 
  the 
  swimming 
  stage 
  and 
  

  

  