﻿778 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [20] 
  

  

  If 
  we 
  dow 
  recollect 
  that 
  the 
  most 
  important 
  elements 
  of 
  the 
  organic 
  

   deposits 
  have 
  descended 
  from 
  the 
  superficial 
  waters, 
  and 
  that 
  the 
  vari- 
  

   ations 
  in 
  contour 
  of 
  the 
  bottom 
  of 
  the 
  sea 
  cannot 
  of 
  themselves 
  prevent 
  

   the 
  debris 
  of 
  animals 
  and 
  plants 
  from 
  accumulating 
  upon 
  the 
  bottom, 
  

   their 
  absence 
  in 
  the 
  red 
  clay 
  areas 
  can 
  only 
  be 
  explained 
  by 
  a 
  decom- 
  

   position 
  under 
  the 
  action 
  of 
  a 
  cause 
  which 
  we 
  must 
  seek 
  to 
  discover. 
  

  

  Pteropod 
  ooze, 
  it 
  will 
  be 
  remembered, 
  is 
  a 
  calcareous 
  organic 
  deposit, 
  

   iu 
  which 
  the 
  remains 
  of 
  Pteropods 
  and 
  other 
  pelagic 
  Mollusca 
  are 
  pres- 
  

   ent, 
  though 
  they 
  do 
  not 
  always 
  form 
  a 
  preponderating 
  constituent, 
  and 
  

   it 
  has 
  been 
  found 
  that 
  their 
  presence 
  is 
  in 
  correlation 
  with 
  the 
  bathy- 
  

   metrical 
  distribution. 
  

  

  In 
  studying 
  the 
  nature 
  of 
  the 
  calcareous 
  elements 
  which 
  are 
  deposited 
  

   in 
  the 
  pelagic 
  areas 
  it 
  has 
  been 
  noticed 
  that, 
  like 
  the 
  shells 
  gf 
  the 
  Fo- 
  

   ramiuifera, 
  those 
  of 
  the 
  Thecosomatous 
  Pteropoda, 
  which 
  live 
  everywhere 
  

   in 
  the 
  superficial 
  waters, 
  especially 
  in 
  the 
  tropics, 
  become 
  fewer 
  in 
  num- 
  

   ber 
  as 
  the 
  depth 
  from 
  which 
  the 
  sediments 
  are 
  derived 
  increases. 
  We 
  

   have 
  just 
  observed 
  that 
  the 
  shells 
  of 
  Foraminifera 
  disappear 
  gradually 
  as 
  

   we 
  descend 
  along 
  a 
  series 
  of 
  soundings 
  from 
  a 
  point 
  where 
  the 
  Globi- 
  

   gerina 
  ooze 
  has 
  abundance 
  of 
  carbonate 
  of 
  lime 
  towards 
  deeper 
  regions; 
  

   but 
  we 
  notice 
  also 
  that 
  when 
  the 
  sounding-rod 
  brings 
  up 
  a 
  graduated 
  

   series 
  of 
  sediments 
  from 
  a 
  declivity 
  descending 
  into 
  deep 
  water, 
  among 
  

   the 
  calcareous 
  shells, 
  those 
  of 
  the 
  Pteropods 
  and 
  Heteropods 
  disappear 
  

   first 
  in 
  proportion 
  as 
  the 
  depth 
  increases. 
  At 
  depths 
  less 
  than 
  1,400 
  

   fathoms 
  in 
  the 
  tropics 
  a 
  Pteropod 
  ooze 
  is 
  found 
  with 
  abundant 
  remains 
  

   of 
  Heteropods 
  and 
  Pteropods; 
  deeper 
  soundings 
  then 
  give 
  a 
  Globigerina 
  

   ooze 
  without 
  these 
  molluscan 
  remains 
  ; 
  and 
  in 
  the 
  still 
  greater 
  depths, 
  

   as 
  before 
  mentioned, 
  there 
  is 
  a 
  red 
  clay 
  in 
  which 
  calcareous 
  organisms 
  

   are 
  nearly 
  if 
  not 
  quite 
  absent. 
  

  

  In 
  this 
  manner, 
  then, 
  it 
  is 
  shown 
  that 
  the 
  remains 
  of 
  calcareous 
  or- 
  

   ganisms 
  are 
  completely 
  eliminated 
  in 
  the 
  greatest 
  depths 
  of 
  the 
  ocean. 
  

   For 
  if 
  such 
  be 
  not 
  the 
  case 
  why 
  do 
  we 
  find 
  all 
  these 
  shells 
  at 
  the 
  

   bottom 
  of 
  the 
  shallower 
  depths 
  and 
  not 
  at 
  all 
  in 
  the 
  greater 
  depths, 
  

   although 
  they 
  are 
  equally 
  abundant 
  on 
  the 
  surface 
  at 
  both 
  places? 
  

   There 
  is 
  reason 
  to 
  think 
  that 
  this 
  solution 
  of 
  calcareous 
  shells 
  is 
  due 
  

   to 
  the 
  presence 
  of 
  carbonic 
  acid 
  throughout 
  all 
  depths 
  of 
  ocean 
  water. 
  

   It 
  is 
  well 
  known 
  that 
  this 
  substance 
  dissolved 
  in 
  water 
  is 
  an 
  energetic 
  

   solvent 
  of 
  calcareous 
  matter. 
  The 
  investigations 
  of 
  Buchanan 
  and 
  

   Dittmar 
  have 
  shown 
  that 
  carbonic 
  acid 
  exists 
  in 
  a 
  free 
  state 
  in 
  sea 
  

   water, 
  and, 
  in 
  the 
  second 
  place, 
  Dittmar's 
  analyses 
  show 
  that 
  deep- 
  sea 
  

   water 
  contains 
  more 
  lime 
  than 
  surface 
  water. 
  This 
  is 
  a 
  confirmation 
  

   of 
  the 
  theory 
  which 
  regards 
  carbonic 
  acid 
  as 
  the 
  agent 
  concerned 
  in 
  

   the 
  total 
  or 
  partial 
  solution 
  of 
  the 
  surface 
  shells 
  before 
  or 
  immediately 
  

   after 
  they 
  reach 
  the 
  bottom 
  of 
  the 
  ocean, 
  and 
  is 
  likewise 
  in 
  relation 
  

   with 
  the 
  fact 
  that 
  in 
  high 
  latitudes, 
  where 
  fewer 
  calcareous 
  organisms 
  

   are 
  found 
  at 
  the 
  surface, 
  their 
  remains 
  are 
  removed 
  at 
  lesser 
  depths 
  

   than 
  where 
  these 
  organisms 
  are 
  in 
  greater 
  abundance. 
  It 
  is 
  not 
  im- 
  

  

  