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  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  [12] 
  

  

  are 
  secured. 
  This 
  leaves 
  a 
  space 
  about 
  5 
  feet 
  6 
  iuches 
  in 
  length 
  between 
  

   the 
  partitions. 
  In 
  this 
  space 
  6 
  or 
  8 
  large 
  glass 
  jars 
  are 
  supported 
  upon 
  

   a 
  frame, 
  with 
  their 
  tops 
  downward. 
  Those 
  used 
  for 
  the 
  purpose 
  at 
  

   Wood's 
  Holl 
  are 
  ordinary 
  cylindrical, 
  four-gallon 
  specimen 
  jars, 
  with 
  a 
  

   half-inch 
  hole 
  drilled 
  in 
  the 
  bottom. 
  The 
  stoppers 
  of 
  the 
  jars 
  are 
  re- 
  

   moved, 
  and 
  a 
  single 
  thickness 
  of 
  coarse 
  cheese-cloth 
  is 
  secured 
  over 
  the 
  

   mouth 
  with 
  strong 
  twine. 
  The 
  jar 
  is 
  then 
  inverted 
  and 
  lowered 
  into 
  

   trough, 
  so 
  that 
  its 
  bottom 
  is 
  about 
  even 
  with 
  the 
  top 
  of 
  the 
  trough. 
  

   Strips 
  nailed 
  across 
  the 
  top 
  of 
  the 
  trough 
  serve 
  to 
  keep 
  the 
  jars 
  upright. 
  

   The 
  accompanying 
  figure, 
  showing 
  the 
  device 
  in 
  longitudinal 
  vertical 
  

  

  section, 
  modified 
  and 
  designed 
  on 
  a 
  somewhat 
  smaller 
  scale 
  than 
  £he 
  de- 
  

   vice 
  now 
  in 
  use 
  and 
  accommodating 
  only 
  four 
  jars 
  (two 
  in 
  a 
  row), 
  will 
  en- 
  

   able 
  the 
  reader 
  to 
  get 
  a 
  clear 
  conception 
  of 
  the 
  way 
  in 
  which 
  the 
  appa- 
  

   ratus 
  is 
  used. 
  The 
  trough 
  A 
  is 
  filled 
  with 
  unfiltered 
  sea-water 
  through 
  

   the 
  faucet 
  i, 
  the 
  water 
  rising 
  to 
  the 
  level 
  of 
  the 
  line 
  a 
  before 
  the 
  capa- 
  

   cious 
  outlet 
  siphon 
  s 
  begins 
  to 
  operate. 
  This 
  siphon, 
  through 
  which 
  

   the 
  water 
  runs 
  out 
  of 
  the 
  trough 
  faster 
  than 
  it 
  comes 
  in 
  at 
  i, 
  soon 
  brings 
  

   the 
  water 
  down 
  to 
  the 
  level 
  of 
  the 
  line 
  &, 
  when 
  the 
  siphon 
  takes 
  in 
  air 
  and 
  

   ceases 
  to 
  operate, 
  after 
  which 
  the 
  trough 
  again 
  slowly 
  fills 
  up 
  with 
  water 
  

   to 
  the 
  level 
  of 
  the 
  line 
  a. 
  This 
  process 
  is 
  repeated 
  automatically, 
  and 
  

   as 
  long 
  as 
  the 
  water 
  is 
  permitted 
  to 
  flow 
  through 
  the 
  device. 
  It 
  requires 
  

   ten 
  minutes 
  for 
  the 
  water 
  to 
  rise 
  or 
  fall 
  from 
  the 
  one 
  level 
  to 
  the 
  other; 
  

   and, 
  since 
  the 
  jars 
  have 
  only 
  a 
  cloth 
  tied 
  over 
  the 
  mouth 
  below, 
  the 
  

   water 
  rises 
  and 
  falls 
  to 
  the 
  same 
  extent 
  in 
  them. 
  This 
  very 
  slow 
  and 
  

   gentle 
  rise 
  and 
  fall 
  of 
  the 
  water 
  in 
  the 
  jars 
  and 
  trough 
  has 
  been 
  found 
  

   sufficient 
  to 
  aerate 
  the 
  eggs 
  and 
  give 
  them 
  all 
  the 
  movement 
  they 
  need. 
  

  

  All 
  of 
  the 
  good 
  eggs 
  in 
  this 
  contrivance 
  float 
  at 
  the 
  surface; 
  some, 
  

   during 
  the 
  latter 
  stages 
  of 
  hatching, 
  will 
  fall 
  below 
  the 
  surface, 
  but 
  if 
  

   such 
  ova 
  are 
  washed, 
  they 
  will 
  again 
  rise 
  to 
  the 
  surface, 
  and 
  an 
  exceed- 
  

   ingly 
  small 
  percentage 
  of 
  the 
  eggs 
  ever 
  sink 
  and 
  die, 
  as 
  in 
  almost 
  all 
  

   of 
  the 
  other 
  forms 
  of 
  apparatus 
  hitherto 
  used. 
  The 
  result 
  is 
  that 
  the 
  

   mortality 
  is 
  probably 
  under 
  5 
  per 
  cent 
  — 
  a 
  percentage 
  of 
  loss 
  not 
  greater 
  

   than 
  that 
  experienced 
  in 
  the 
  most 
  successful 
  treatment 
  of 
  shad 
  ova 
  in 
  - 
  

   the 
  McDonald 
  jar. 
  

  

  The 
  freshly 
  fertilized 
  ova, 
  treated 
  with 
  an 
  abundance 
  of 
  good 
  milt, 
  

   are 
  introduced 
  into 
  the 
  hatching 
  device 
  through 
  the 
  hole 
  in 
  the 
  center 
  

  

  