﻿REPOET 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  97 
  

  

  and 
  before 
  they 
  had 
  cast 
  their 
  spawn. 
  Thus 
  it 
  appeared 
  impossible 
  to 
  

   carry 
  on 
  the 
  flat-fish 
  worlv 
  in 
  this 
  water. 
  In 
  order 
  to 
  liold 
  these 
  fish 
  

   until 
  the 
  radical 
  remedy 
  of 
  repairing- 
  the 
  intake 
  pipes 
  could 
  be 
  applied, 
  

   a 
  simple 
  apparatus 
  was 
  suggested 
  for 
  the 
  speedy 
  dissipation 
  of 
  the 
  

   excess 
  of 
  dissolved 
  air. 
  The 
  superintendent 
  suspended 
  high 
  above 
  

   the 
  upper 
  tank 
  of 
  each 
  series 
  of 
  three 
  a 
  dish 
  pan 
  with 
  the 
  bottom 
  per- 
  

   forated 
  with 
  many 
  small 
  holes. 
  The 
  water 
  was 
  piped 
  up 
  from 
  the 
  

   taps 
  to 
  these 
  pans, 
  entering 
  them 
  in 
  several 
  jets 
  from 
  a 
  metal 
  delivery 
  

   head, 
  the 
  jets 
  impinging 
  against 
  the 
  side 
  of 
  the 
  pan, 
  to 
  flow 
  down 
  

   through 
  the 
  perforations 
  and 
  drop 
  several 
  feet 
  in 
  a 
  shower 
  of 
  sepa- 
  

   rate 
  streams 
  to 
  the 
  surface 
  of 
  the 
  water 
  in 
  the 
  flat-fish 
  tanks. 
  This 
  

   device, 
  which 
  could 
  aerate 
  water 
  at 
  all 
  deficient 
  in 
  dissolved 
  air, 
  

   accomplishes 
  a 
  de-aeration 
  for 
  supersaturated 
  water. 
  The 
  de-aerating 
  

   process 
  removed 
  sufiicient 
  of 
  the 
  excess 
  of 
  air 
  to 
  hold 
  the 
  flat 
  fish 
  with- 
  

   out 
  loss, 
  and 
  flat-fish 
  operations 
  were 
  carried 
  on 
  in 
  this 
  way 
  during 
  

   the 
  season. 
  

  

  Plates 
  made 
  from 
  the 
  blood 
  of 
  the 
  dead 
  and 
  dying 
  fish 
  indicate 
  the 
  

   absence 
  of 
  bacteria 
  from 
  the 
  blood, 
  and 
  indeed 
  the 
  explanation 
  given 
  

   above, 
  ascribing 
  the 
  mortality 
  to 
  purely 
  ph3\sical 
  causes, 
  excludes 
  

   bacteria 
  from 
  any 
  part 
  in 
  it. 
  Moreover, 
  the 
  immediate 
  appearance 
  of 
  

   gas 
  renders 
  it 
  practically 
  impossible 
  that 
  it 
  should 
  be 
  the 
  product 
  of 
  a 
  

   gas-producing 
  organism, 
  for 
  the 
  reaction 
  occurs 
  too 
  quickly. 
  It 
  is 
  

   evident 
  that 
  this 
  particular 
  epidemic 
  or 
  mortality 
  is 
  not 
  an 
  infection, 
  

   and 
  that 
  contamination 
  of 
  the 
  water 
  is 
  not 
  related 
  in 
  any 
  way 
  to 
  this 
  

   disease 
  of 
  fishes. 
  

  

  The 
  immunit}^ 
  of 
  the 
  cod 
  fry 
  and 
  eggs 
  from 
  the 
  gas 
  disease 
  is 
  to 
  be 
  

   commented 
  upon. 
  These 
  are 
  incubated 
  and 
  hatched 
  in 
  the 
  same 
  sta- 
  

   tion 
  water 
  that 
  is 
  fatal 
  to 
  adults 
  of 
  all 
  species 
  experimented 
  with, 
  

   including 
  the 
  adult 
  cod. 
  In 
  no 
  case 
  have 
  they 
  been 
  seen 
  to 
  exhibit 
  the 
  

   gaseous 
  symptoms, 
  and 
  hatching 
  operations 
  have 
  gone 
  on 
  as 
  usual. 
  

   The 
  egg 
  and 
  the 
  fry 
  are 
  of 
  course 
  very 
  differently 
  organized 
  from 
  the 
  

   adult, 
  their 
  tissues 
  are 
  not 
  yet 
  so 
  differentiated 
  and 
  specialized, 
  and 
  the 
  

   gaseous 
  interchange 
  not 
  to 
  be 
  compared, 
  in 
  degree 
  at 
  least, 
  with 
  that 
  

   of 
  the 
  adult. 
  Were 
  the 
  fry 
  to 
  ])e 
  held 
  for 
  a 
  time, 
  it 
  is 
  to 
  be 
  expected 
  

   that 
  the}' 
  would 
  fall 
  victims 
  to 
  the 
  disease, 
  but 
  the}^ 
  are 
  planted 
  almost 
  

   as 
  soon 
  as 
  hatched. 
  

  

  Of 
  any 
  factors 
  that 
  readil}^ 
  occur 
  to 
  mind 
  as 
  playing 
  a 
  part 
  in 
  the 
  

   immunity, 
  that 
  of 
  temperature 
  is 
  probably 
  the 
  most 
  important. 
  The 
  

   fry 
  can 
  scarcel}^ 
  be 
  conceived 
  to 
  maintain 
  a 
  temperature 
  appreciably 
  

   above 
  that 
  of 
  the 
  surrounding 
  water. 
  There 
  must 
  be 
  some 
  combustion 
  

   taking 
  place, 
  nevertheless, 
  and 
  theoretically 
  there 
  should 
  be 
  a 
  differ- 
  

   ence 
  in 
  temperature. 
  It 
  is 
  to 
  be 
  remembered, 
  however, 
  that 
  it 
  is 
  not 
  

   the 
  difference 
  in 
  temperature 
  between 
  blood 
  and 
  water, 
  but 
  between 
  

   the 
  systemic 
  blood 
  and 
  the 
  gill 
  blood 
  that 
  throws 
  the 
  gas 
  from 
  solution. 
  

   The 
  gill 
  blood 
  is 
  cooled 
  by 
  its 
  intimate 
  contact 
  with 
  the 
  water, 
  and 
  the 
  

  

  F. 
  C. 
  1903 
  7 
  

  

  