﻿330 
  DR 
  DAVY 
  S 
  OBSERVATIONS 
  ON 
  THE 
  CHARR. 
  

  

  in 
  water 
  ; 
  they 
  were 
  kept 
  part 
  of 
  the 
  time 
  in 
  the 
  open 
  air, 
  and 
  part 
  of 
  it 
  in 
  the 
  room 
  

   of 
  equable 
  temperature 
  : 
  each 
  fish 
  had 
  been 
  hatched 
  about 
  six 
  weeks. 
  The 
  one 
  

   in 
  water, 
  with 
  oxygen, 
  put 
  in 
  on 
  the 
  28th 
  of 
  January, 
  w 
  T 
  as 
  very 
  active 
  till 
  about 
  

   the 
  middle 
  of 
  February 
  ; 
  about 
  the 
  24th 
  of 
  that 
  month 
  it 
  began 
  to 
  appear 
  lan- 
  

   guid, 
  and 
  it 
  was 
  more 
  so 
  on 
  the 
  26th, 
  when 
  it 
  was 
  taken 
  out 
  and 
  transferred 
  to 
  a 
  

   vessel 
  fully 
  exposed 
  to 
  the 
  air, 
  and 
  the 
  water 
  in 
  which 
  was 
  changed 
  daily. 
  

   Though 
  it 
  lived 
  till 
  the 
  18th 
  of 
  March 
  it 
  did 
  not 
  recover 
  its 
  activity. 
  Its 
  growth 
  

   whilst 
  under 
  oxygen 
  was 
  much 
  the 
  same 
  as 
  if 
  it 
  had 
  been 
  kept 
  in 
  water 
  exposed 
  

   to 
  the 
  air 
  and 
  changed 
  daily. 
  The 
  oxygen 
  used 
  was 
  not 
  tested 
  for 
  carbonic 
  acid 
  ; 
  

   by 
  the 
  taper-test 
  its 
  purity 
  did 
  not 
  appear 
  to 
  be 
  impaired. 
  The 
  trial 
  with 
  com- 
  

   mon 
  air 
  was 
  commenced 
  on 
  the 
  7th 
  of 
  February 
  ; 
  on 
  the 
  13th, 
  the 
  young 
  fish 
  was 
  

   found 
  dead. 
  As 
  there 
  was 
  a 
  small 
  spot 
  of 
  stagnant 
  blood 
  in 
  the 
  vitelline 
  mem- 
  

   brane, 
  its 
  death 
  might 
  be 
  owing 
  to 
  disease 
  unconnected 
  with 
  the 
  peculiarity 
  of 
  

   circumstances 
  in 
  which 
  it 
  was 
  placed. 
  On 
  the 
  28th 
  of 
  March 
  I 
  repeated 
  the 
  ex- 
  

   periment 
  with 
  a 
  young 
  fish 
  which 
  was 
  vigorous 
  and 
  active. 
  Taken 
  out 
  on 
  the 
  

   4th 
  of 
  April, 
  its 
  activity 
  seemed 
  unimpaired 
  ; 
  it 
  fed 
  greedily. 
  This 
  fish 
  had 
  been 
  

   hatched 
  about 
  seven 
  weeks. 
  

  

  The 
  only 
  other 
  trials 
  I 
  have 
  made 
  have 
  been 
  on 
  the 
  effects 
  of 
  temperature. 
  — 
  

   an 
  influence 
  that 
  this 
  fish 
  appears 
  to 
  be 
  peculiarly 
  sensitive 
  of, 
  as 
  indicated 
  in 
  all 
  

   its 
  habits, 
  and 
  in 
  the 
  circumstance 
  that 
  it 
  is 
  only 
  found 
  in 
  those 
  lakes 
  in 
  which, 
  

   in 
  consequence 
  of 
  their 
  great 
  depth, 
  it 
  can 
  find 
  a 
  retreat 
  in 
  summer 
  and 
  winter 
  in 
  

   water 
  of 
  about 
  40' 
  Fahr. 
  On 
  the 
  28 
  th 
  of 
  March 
  I 
  transferred 
  into 
  water, 
  of 
  the 
  

   temperature 
  of 
  83°, 
  a 
  young 
  charr 
  that 
  had 
  been 
  hatched 
  not 
  quite 
  seven 
  weeks. 
  

   It 
  rushed 
  about 
  for 
  a 
  second 
  or 
  two, 
  then 
  turned 
  on 
  its 
  back 
  and 
  rose 
  almost 
  in- 
  

   animate 
  to 
  the 
  surface. 
  The 
  heart 
  and 
  gill-covers 
  being 
  still 
  in 
  motion, 
  it 
  was 
  

   instantly 
  put 
  back 
  to 
  the 
  water 
  from 
  which 
  it 
  had 
  been 
  taken 
  of 
  52 
  . 
  It 
  made 
  

   one 
  or 
  two 
  efforts 
  as 
  if 
  reviving, 
  swimming 
  for 
  a 
  few 
  seconds 
  in 
  a 
  natural 
  posi- 
  

   tion 
  ; 
  but 
  in 
  less 
  than 
  a 
  minute 
  it 
  was 
  dead, 
  the 
  heart 
  having 
  ceased 
  to 
  act 
  : 
  thus, 
  

   compared 
  with 
  the 
  effects 
  of 
  a 
  solution 
  of 
  common 
  salt, 
  offering 
  a 
  remarkable 
  con- 
  

   trast. 
  On 
  the 
  29th 
  of 
  the 
  same 
  month, 
  a 
  young 
  charr 
  of 
  about 
  the 
  same 
  age 
  as 
  

   the 
  preceding 
  was 
  put 
  into 
  water 
  of 
  75° 
  : 
  it 
  immediately 
  became 
  very 
  restless 
  ; 
  

   its 
  gill-covers 
  moving 
  rapidly. 
  After 
  a 
  quarter 
  of 
  an 
  hour, 
  when 
  the 
  temperature 
  

   of 
  the 
  water 
  had 
  fallen 
  to 
  70 
  , 
  it 
  lay 
  still 
  at 
  the 
  bottom 
  and 
  not 
  apparently 
  dis- 
  

   tressed, 
  except 
  that 
  the 
  movement 
  of 
  the 
  gill-covers 
  and 
  the 
  action 
  of 
  the 
  heart 
  

   were 
  unduly 
  quick. 
  In 
  an 
  hour 
  and 
  a-half, 
  when 
  the 
  water 
  was 
  60°, 
  it 
  was 
  still 
  

   at 
  rest 
  : 
  some 
  hours 
  later, 
  when 
  the 
  water 
  was 
  54 
  c 
  , 
  it 
  seemed 
  well 
  ; 
  and, 
  on 
  the 
  

   following 
  day, 
  put 
  into 
  fresh 
  water, 
  it 
  appeared 
  as 
  active 
  as 
  before. 
  

  

  I 
  have 
  now 
  to 
  conclude. 
  This 
  I 
  shall 
  do 
  without 
  entering 
  on 
  the 
  embryology 
  

   of 
  the 
  charr, 
  — 
  a 
  vast 
  subject, 
  which, 
  in 
  the 
  instance 
  of 
  one 
  of 
  the 
  family 
  of 
  the 
  

  

  