﻿EEPORT 
  OF 
  COMMISSIONEK 
  OF 
  FISH 
  AND 
  FISHERIES. 
  95 
  

  

  not 
  very 
  marked. 
  When 
  nearly 
  all 
  the 
  filaments 
  were 
  well 
  filled 
  with 
  

   gas 
  the 
  condition 
  modified 
  somewhat 
  the 
  microscopic 
  appearance 
  of 
  

   the 
  gill, 
  and 
  the 
  individual 
  emboli 
  were 
  seen 
  on 
  a 
  careful 
  inspection 
  

   by 
  the 
  naked 
  eye. 
  Gas 
  emboli 
  were 
  the 
  usual 
  immediate 
  cause 
  of 
  

   death 
  by 
  asphyxiation. 
  

  

  On 
  the 
  exterior 
  of 
  the 
  fish, 
  besides 
  the 
  minute 
  bubbles 
  that 
  appear 
  

   almost 
  immediatel}^ 
  after 
  immersion 
  in 
  the 
  water, 
  blebs 
  appear 
  after 
  

   some 
  lapse 
  of 
  time 
  which 
  are 
  made 
  by 
  an 
  accumulation 
  of 
  gas 
  beneath 
  

   the 
  membranous 
  portions 
  of 
  the 
  epithelium. 
  They 
  may 
  hold 
  several 
  

   centimeters 
  of 
  gas, 
  and 
  occur 
  chiefly 
  in 
  the 
  fins 
  in 
  nearly 
  all 
  species, 
  

   also 
  on 
  the 
  belly 
  of 
  the 
  small 
  sculpin, 
  and 
  rarely 
  on 
  the 
  cornea. 
  

   "Pop-eye" 
  was 
  not 
  observed 
  at 
  this 
  time. 
  

  

  The 
  agent 
  that 
  produces 
  this 
  fatal 
  evolution 
  of 
  gas 
  is 
  evidently 
  

   present 
  in 
  the 
  water 
  and 
  is 
  introduced 
  into 
  it 
  somewhere 
  between 
  the 
  

   suction 
  intake 
  and 
  the 
  taps 
  that 
  deliver 
  the 
  water 
  at 
  the 
  points 
  where 
  

   it 
  is 
  used 
  — 
  in 
  aquaria 
  and 
  hatchery; 
  for 
  neither 
  in 
  the 
  f3^ke 
  net, 
  8 
  feet 
  

   beneath 
  the 
  surface 
  of 
  the 
  water 
  in 
  the 
  harbor, 
  nor 
  in 
  live 
  boxes 
  at 
  the 
  

   surface 
  of 
  the 
  basin 
  in 
  close 
  proximity 
  to 
  the 
  intake, 
  do 
  fish 
  die 
  or 
  

   exhibit 
  any 
  of 
  the 
  symptoms 
  described. 
  After 
  this 
  water 
  has 
  passed 
  

   from 
  the 
  basin 
  through 
  the 
  system 
  of 
  pipes, 
  including 
  the 
  steam 
  pump 
  

   and 
  the 
  supply 
  tanks, 
  it 
  possesses 
  the 
  power 
  to 
  produce 
  such 
  symptoms, 
  

   ending 
  invariably 
  in 
  the 
  death 
  of 
  the 
  fish. 
  This 
  pathologic 
  agent 
  is 
  

   volatile, 
  for 
  if 
  one 
  of 
  the 
  large 
  stationary 
  aquaria 
  be 
  filled 
  and 
  allowed 
  

   to 
  stand 
  for 
  seven 
  days 
  with 
  the 
  flow 
  cut 
  off, 
  the 
  water 
  has 
  lost 
  mark- 
  

   edly 
  its 
  lethal 
  power; 
  it 
  will 
  produce 
  external 
  bubbles 
  on 
  fishes, 
  but 
  

   will 
  not 
  kill. 
  About 
  2^ 
  gallons 
  of 
  the 
  freshly 
  drawn 
  water 
  held 
  in 
  the 
  

   cylindrical 
  glass 
  hatchery 
  jars 
  cease 
  entirely 
  to 
  produce 
  the 
  external 
  

   bubbles 
  after 
  standing 
  from 
  two 
  to 
  three 
  daj^s. 
  In 
  proportion 
  as 
  the 
  

   water 
  is 
  exposed 
  to 
  the 
  air 
  it 
  loses 
  this 
  quality, 
  and 
  an 
  aeration 
  appa- 
  

   ratus 
  which 
  divides 
  the 
  water 
  into 
  fine 
  streams 
  immediately 
  dissipates 
  

   this 
  power 
  to 
  such 
  an 
  extent 
  that 
  the 
  fish 
  do 
  not 
  die 
  in 
  it. 
  Thus 
  an 
  

   aquarium 
  that 
  received 
  several 
  capillary 
  jets 
  spurting 
  into 
  it 
  from 
  

   a 
  distance 
  of 
  several 
  feet 
  held 
  its 
  fish 
  successfully, 
  while 
  the 
  fish 
  in 
  a 
  

   control 
  aquarium 
  which 
  received 
  the 
  same 
  amount 
  of 
  capillary 
  flow, 
  

   and 
  which 
  differed 
  only 
  in 
  the 
  fact 
  that 
  the 
  capillary 
  jets 
  were 
  sub- 
  

   merged 
  within 
  the 
  aquarium, 
  died 
  after 
  one 
  day. 
  The 
  agent 
  evidently 
  

   passes 
  off 
  into 
  the 
  air. 
  

  

  In 
  the 
  course 
  of 
  some 
  aquarium 
  experiments, 
  using 
  water 
  directly 
  

   from 
  the 
  pump, 
  it 
  became 
  evident 
  that 
  the 
  water 
  passing 
  through 
  the 
  

   pump 
  constantly 
  contained 
  a 
  considerable 
  quantity 
  of 
  air 
  in 
  small 
  bub- 
  

   bles. 
  This 
  air 
  must 
  have 
  entered 
  the 
  suction 
  area, 
  and 
  a 
  wooden 
  sup- 
  

   ply 
  pipe 
  between 
  basin 
  and 
  pump, 
  several 
  feet 
  beneath 
  the 
  ground, 
  

   was 
  subsequently 
  found 
  to 
  leak 
  in 
  a 
  number 
  of 
  places. 
  The 
  pressure 
  

   of 
  this 
  air 
  in 
  the 
  water 
  suggests 
  immediately 
  an 
  explanation 
  which 
  is 
  in 
  

   accord 
  with 
  all 
  the 
  facts 
  observed. 
  Water 
  absorbs 
  air 
  in 
  proportion 
  

  

  