﻿152 
  REPORT 
  OF 
  COMMISSIONER 
  OP 
  FISH 
  AND 
  FISHERIES. 
  

  

  thus 
  expelling- 
  all 
  the 
  air 
  from 
  the 
  feed-tube 
  ; 
  otherwise 
  it 
  would 
  rise 
  

   in 
  bubbles, 
  throwing 
  a 
  portion 
  of 
  the 
  eggs 
  out 
  through 
  the 
  outlet-tube. 
  

  

  With 
  a 
  proper 
  quantity 
  of 
  semi-buoyant 
  eggs 
  in 
  the 
  jar 
  and 
  the 
  

   water 
  turned 
  on 
  and 
  regulated, 
  the 
  movement 
  of 
  the 
  current 
  estab- 
  

   lishes 
  a 
  regular 
  boiling 
  motion 
  in 
  the 
  mass 
  of 
  eggs, 
  which 
  brings 
  each 
  

   m 
  succession 
  to 
  the 
  surface. 
  This 
  motion 
  may 
  be 
  regulated 
  without 
  

   altering 
  the 
  quantity 
  of 
  water. 
  By 
  loosening 
  the 
  upper 
  binding-screw 
  

   of 
  the 
  central 
  stufiling-box, 
  and 
  pushing 
  the 
  feed-tube 
  down 
  until 
  it 
  

   almost 
  comes 
  in 
  contact 
  with 
  the 
  bottom 
  of 
  the 
  jar, 
  the 
  motion 
  of 
  the 
  

   eggs 
  is 
  increased. 
  If 
  the 
  jar 
  is 
  working 
  properly, 
  the 
  dead 
  eggs 
  when 
  

   brought 
  to 
  the 
  surface 
  remain 
  on 
  top, 
  forming 
  a 
  distinct 
  layer, 
  and 
  by 
  

   [)ushing 
  down 
  the 
  outlet 
  tube 
  a 
  suitable 
  distance 
  they 
  are 
  lifted 
  up 
  

   by 
  the 
  escai)ing 
  current 
  and 
  taken 
  out. 
  

  

  When 
  the 
  water 
  is 
  turned 
  on 
  for 
  the 
  first 
  time 
  the 
  jar 
  should 
  be 
  

   watched 
  closely 
  until 
  a 
  regular 
  motion 
  has 
  been 
  established. 
  When 
  

   eggs 
  have 
  stood 
  15 
  or 
  20 
  minutes 
  in 
  the 
  jar 
  before 
  the 
  water 
  is 
  turned 
  

   on 
  they 
  do 
  not 
  readily 
  yield 
  to 
  the 
  boiling 
  motion, 
  but 
  tend 
  to 
  rise 
  in 
  a 
  

   solid 
  mass 
  to 
  the 
  top 
  of 
  the 
  jar. 
  By 
  quickly 
  starting 
  and 
  stopping 
  the 
  

   current 
  the 
  mass 
  is 
  readily 
  disintegrated. 
  The 
  degree 
  or 
  intensity 
  of 
  

   motion 
  of 
  the 
  eggs 
  varies 
  not 
  only 
  with 
  their 
  age 
  and 
  condition, 
  but 
  also 
  

   with 
  the 
  condition 
  of 
  the 
  water. 
  If 
  the 
  water 
  is 
  muddy, 
  the 
  motion 
  

   should 
  be 
  rapid 
  enough 
  to 
  prevent 
  mud 
  settling 
  either 
  on 
  the 
  eggs 
  or 
  in 
  

   the 
  bottom 
  of 
  the 
  jar. 
  Ordinarily 
  the 
  best 
  motion 
  is 
  that 
  which 
  readily 
  

   brings 
  the 
  dead 
  eggs 
  to 
  the 
  surface. 
  After 
  the 
  hatching 
  has 
  i)rogressed 
  

   far 
  enough 
  to 
  dispose 
  of 
  a 
  portion 
  of 
  the 
  eggs 
  there 
  is 
  less 
  resistance 
  to 
  

   the 
  current, 
  and 
  it 
  should 
  be 
  reduced 
  by 
  shutting 
  off 
  part 
  of 
  the 
  supply 
  

   or 
  by 
  slightly 
  lifting 
  the 
  central 
  tube. 
  If 
  the 
  motion 
  is 
  not 
  reduced 
  

   from 
  time 
  to 
  time 
  as 
  the 
  hatching 
  progresses, 
  shells 
  will 
  be 
  carried 
  over 
  

   into 
  the 
  receiving-tank 
  with 
  the 
  fish 
  and, 
  being 
  very 
  light, 
  will 
  be 
  drawn 
  

   against 
  the 
  outlet 
  screen, 
  causing 
  an 
  overflow. 
  The 
  motion 
  should 
  be 
  

   so 
  gentle 
  at 
  the 
  time 
  of 
  the 
  greatest 
  hatching 
  as 
  barely 
  to 
  induce 
  the 
  fish 
  

   to 
  swim 
  out 
  of 
  the 
  jar 
  and 
  leave 
  their 
  cast-off 
  shells 
  behind. 
  

  

  Very 
  healthy 
  eggs, 
  exjiosed 
  to 
  bright 
  direct 
  sunshine, 
  hatch 
  so 
  rapidly 
  

   that 
  the 
  combined 
  effort 
  of 
  the 
  swarming 
  mass 
  of 
  young 
  fish 
  will 
  

   establish 
  sufficient 
  current 
  to 
  draw 
  some 
  shells 
  over 
  into 
  the 
  receiving- 
  

   tank. 
  This 
  may 
  be 
  modified 
  by 
  placing 
  a 
  screen 
  between 
  the 
  jar 
  and 
  

   the 
  light. 
  The 
  shells 
  under 
  normal 
  conditions 
  remain 
  and 
  form 
  a 
  

   cloud-like 
  layer 
  above 
  the 
  mass 
  of 
  working 
  eggs. 
  As 
  they 
  accumulate 
  

   they 
  should 
  be 
  removed 
  by 
  shoving 
  down 
  the 
  outlet 
  tube 
  until 
  they 
  are 
  

   drawn 
  up 
  with 
  the 
  escaping 
  water. 
  A 
  good 
  j^lan 
  is 
  to 
  draw 
  several 
  

   jars 
  in 
  succession 
  into 
  a 
  large 
  pan, 
  whence 
  any 
  fish 
  coming 
  over 
  with 
  

   the 
  shells 
  may 
  be 
  ladled 
  into 
  the 
  receiving- 
  tank. 
  

  

  A 
  remnant 
  of 
  eggs 
  may 
  be 
  long 
  in 
  hatching, 
  and 
  they 
  should 
  be 
  

   poured 
  into 
  a 
  large, 
  clean, 
  bright 
  pan 
  and 
  exposed 
  to 
  bright 
  sunlight, 
  

   Avhen 
  they 
  will 
  hatch 
  in 
  five 
  or 
  ten 
  minutes. 
  

  

  If 
  the 
  connection 
  of 
  the 
  jar 
  must 
  be 
  broken, 
  it 
  is 
  essential 
  that 
  the 
  

   rubber 
  feed-tube 
  does 
  not 
  drop 
  down 
  and 
  siphon 
  the 
  eggs 
  from 
  the 
  jar. 
  

  

  