﻿184 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  fish 
  in 
  an 
  aquarium 
  at 
  Washington 
  deposited 
  a 
  string 
  of 
  eggs 
  88 
  inches 
  

   long, 
  4 
  inches 
  wide 
  at 
  one 
  end 
  and 
  2 
  at 
  the 
  other, 
  whose 
  weight 
  after 
  

   fertilization 
  was 
  41 
  ounces 
  avoirdupois, 
  while 
  the 
  weight 
  of 
  the 
  fish 
  

   before 
  the 
  escape 
  of 
  the 
  eggs 
  was 
  only 
  24 
  ounces. 
  

  

  A 
  cavity 
  extends 
  the 
  whole 
  length 
  of 
  the 
  egg 
  mass, 
  its 
  walls 
  being 
  

   formed 
  by 
  the 
  delicate 
  membrane 
  in 
  which 
  the 
  eggs 
  are 
  imbedded. 
  The 
  

   cavity 
  is 
  almost 
  closed, 
  small 
  apertures 
  occurring 
  irregularly, 
  which 
  

   have 
  the 
  appearance 
  of 
  being 
  accidental, 
  but 
  may 
  be 
  natural, 
  in 
  order 
  

   to 
  permit 
  the 
  circulation 
  of 
  water 
  on 
  the 
  inside 
  of 
  the 
  mass. 
  

  

  The 
  egg- 
  string 
  is 
  quite 
  light 
  and 
  resilient 
  or 
  springy, 
  the 
  least 
  agita- 
  

   tion 
  of 
  the 
  water 
  causing 
  a 
  quivering 
  motion 
  of 
  the 
  whole 
  mass. 
  

  

  The 
  diameter 
  of 
  the 
  egg 
  is 
  -1^3 
  inch. 
  The 
  quantity 
  can 
  not 
  be 
  easily 
  

   measured, 
  but 
  the 
  number 
  is 
  approximately 
  28,000 
  to 
  a 
  quart. 
  

  

  The 
  best 
  method 
  of 
  securing 
  the 
  spawn 
  is 
  to 
  place 
  mature 
  fish 
  of 
  

   both 
  sexes 
  in 
  suitable 
  tanks 
  with 
  running 
  water. 
  The 
  females 
  selected 
  

   should 
  be 
  those 
  whose 
  external 
  appearance 
  indicates 
  that 
  the 
  eggs 
  

   are 
  still 
  undeposited. 
  Spawning 
  takes 
  place 
  at 
  night, 
  and 
  the 
  eggs 
  are 
  

   naturally 
  fertilized. 
  Under 
  proper 
  conditions, 
  it 
  is 
  the 
  exception 
  to 
  

   find 
  unfertilized 
  eggs. 
  In 
  the 
  morning 
  the 
  eggs 
  are 
  transferred 
  to 
  the 
  

   hatching 
  apparatus. 
  

  

  The 
  eggs 
  of 
  this 
  fish 
  have 
  been 
  hatched 
  at 
  different 
  stations 
  of 
  the 
  

   Commission. 
  One 
  season, 
  at 
  Central 
  Statiou, 
  Washington, 
  D. 
  C, 
  130 
  

   ripening 
  females 
  and 
  about 
  an 
  equal 
  number 
  of 
  males 
  taken 
  from 
  the 
  

   Potomac 
  were 
  placed 
  in 
  aquarium 
  tanks 
  supplied 
  with 
  water 
  from 
  the 
  

   city 
  water- 
  works. 
  Spawning 
  began 
  March 
  10 
  and 
  continued 
  till 
  April 
  3, 
  

   and 
  98 
  strings, 
  containing 
  nearly 
  1,000,000 
  eggs, 
  were 
  deposited. 
  

  

  The 
  eggs 
  are 
  hatched 
  in 
  the 
  automatic 
  shad 
  jar, 
  provided 
  with 
  a 
  cap 
  

   of 
  fine 
  -meshed 
  wire 
  netting; 
  the 
  usual 
  inflow 
  tube 
  is 
  retained, 
  but 
  the 
  

   siphon 
  tube 
  is 
  withdrawn, 
  the 
  water 
  escaping 
  over 
  the 
  top 
  of 
  the 
  jar. 
  

   The 
  amount 
  of 
  water 
  circulation 
  is 
  not 
  great 
  enough 
  to 
  force 
  the 
  mass 
  

   of 
  eggs 
  to 
  the 
  upper 
  part 
  of 
  the 
  jar 
  or 
  to 
  give 
  much 
  motion 
  to 
  them. 
  

   They 
  are 
  lighter 
  than 
  shad 
  or 
  whitefish 
  eggs, 
  and 
  when 
  put 
  in 
  rapid 
  

   motion 
  to 
  dislodge 
  adhering 
  sediment 
  they 
  would 
  clog 
  the 
  outlet 
  tube 
  

   if 
  the 
  ordinary 
  method 
  of 
  manipulating 
  this 
  jar 
  were 
  employed. 
  

  

  The 
  eggs 
  from 
  several 
  fish 
  may 
  be 
  placed 
  in 
  one 
  jar. 
  They 
  perhaps 
  

   need 
  as 
  little 
  care 
  as 
  any 
  eggs 
  handled 
  by 
  fish-culturists. 
  When 
  one 
  

   string 
  of 
  eggs 
  or 
  one 
  lobe 
  of 
  a 
  string 
  dies 
  it 
  may 
  be 
  removed 
  with 
  a 
  

   small 
  net, 
  or 
  the 
  entire 
  contents 
  of 
  the 
  jar 
  may 
  be 
  turned 
  into 
  a 
  pan. 
  

  

  The 
  period 
  of 
  hatching 
  varies 
  from 
  two 
  to 
  four 
  weeks, 
  according 
  to 
  

   the 
  temperature. 
  As 
  the 
  fry 
  hatch, 
  they 
  pass 
  over 
  into 
  tanks 
  provided 
  

   with 
  screened 
  overflows, 
  where 
  they 
  are 
  held 
  till 
  planted. 
  The 
  fry 
  are 
  

   very 
  hardy, 
  and 
  may 
  be 
  readily 
  retained 
  in 
  aquaria 
  for 
  several 
  weeks. 
  

   The 
  percentage 
  of 
  eggs 
  hatched 
  is 
  large. 
  From 
  one 
  lot 
  of 
  955^000, 
  

   754,000 
  fry, 
  or 
  79 
  per 
  cent, 
  were 
  produced. 
  

  

  