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  REPORT 
  OF 
  COMMISSIONER 
  OB^ 
  FISH 
  AND 
  FISHERIES. 
  

   DIATOMS 
  ON 
  OTHER 
  SUBMERGED 
  OBJECTS. 
  

  

  Any 
  submerged 
  object 
  is 
  capable 
  of 
  and 
  usually 
  does 
  support 
  a 
  

   growth 
  of 
  diatoms 
  after 
  it 
  has 
  been 
  in 
  the 
  water 
  a 
  short 
  time. 
  The 
  

   spiles 
  of 
  the 
  Fish 
  Commission 
  wharf 
  show 
  numerous 
  species, 
  among 
  

   them 
  Lionophora 
  tincta^ 
  the 
  one 
  so 
  abundant 
  on 
  the 
  lobsters. 
  The 
  

   eel 
  grass 
  in 
  all 
  localities 
  is 
  covered 
  with 
  them. 
  Collections 
  from 
  the 
  

   eel 
  grass 
  show 
  the 
  following 
  .species, 
  named 
  approximately 
  in 
  the 
  

   order 
  of 
  abundance: 
  

  

  August 
  5, 
  1902. 
  

  

  Licmophora 
  flabellata 
  (Carmichael) 
  Agardh. 
  

  

  Licmophora 
  tincta 
  Grunow. 
  

  

  Rhabdonema 
  arcuatum 
  (Lyngby) 
  Kiitzing. 
  

  

  Rhabdonema 
  adriaticum 
  Kiitzing. 
  

   August 
  30, 
  1902. 
  

  

  Pleurosigma 
  sp. 
  

  

  Cocconeis 
  scutellum 
  Ehrenberg. 
  • 
  

  

  Melosira 
  sp. 
  

  

  Nitzschia 
  longissima 
  (Brebisson) 
  Ralfs. 
  

  

  Rhabdonema 
  arcuatum 
  (Lyngby) 
  Kiitzing. 
  

  

  Rha])donema 
  adriaticum 
  Kiitzing. 
  

   September 
  10, 
  1902. 
  

  

  Licmophora 
  flabellata 
  (Carmichael) 
  Agardh. 
  

  

  Rhabdonema 
  adriaticum 
  Kiitzing. 
  

  

  Rhabdonema 
  arcuatum 
  (Lyngby) 
  Kiitzing. 
  

  

  Nitzschia 
  longissima 
  (Brebisson) 
  Ralfs. 
  

  

  Synedra 
  affinis 
  Kiitzing. 
  

  

  Pleurosigma 
  sp. 
  

  

  Amphora 
  sp. 
  

  

  Podocystis 
  sp. 
  

  

  The 
  nets 
  of 
  the 
  fish 
  traps, 
  soon 
  after 
  being 
  set, 
  bear 
  a 
  great 
  abun- 
  

   dance 
  of 
  individuals 
  and 
  species, 
  and 
  the 
  bags 
  of 
  the 
  lobster-rearing 
  

   apparatus 
  are 
  particularly 
  well 
  adapted 
  for 
  the 
  attachment 
  and 
  growth 
  

   of 
  many 
  species. 
  The 
  water 
  set 
  in 
  motion 
  by 
  the 
  fans 
  is 
  continually 
  

   passing 
  through 
  the 
  scrim 
  of 
  which 
  the 
  l)ags 
  are 
  composed, 
  and 
  the 
  

   diatoms 
  are 
  filtered 
  out. 
  They 
  become 
  entangled 
  in 
  the 
  fibrous 
  material, 
  

   and 
  begin 
  to 
  grow 
  rapidl}-. 
  It 
  is 
  this 
  growth 
  that 
  is 
  the 
  principal 
  

   cause 
  of 
  the 
  rapid 
  fouling 
  of 
  the 
  bags. 
  At 
  least 
  once 
  in 
  every 
  two 
  or 
  

   three 
  days 
  it 
  was 
  necessary 
  to 
  replace 
  the 
  bags 
  in 
  order 
  to 
  keep 
  up 
  the 
  

   circulation 
  of 
  the 
  water. 
  The 
  following 
  species 
  were 
  found 
  growing 
  

   on 
  the 
  bags 
  between 
  May 
  29, 
  1902, 
  and 
  July 
  1, 
  1902: 
  

  

  Nitzschia 
  longissima 
  (Brebisson) 
  Ralfs. 
  

  

  Licmophora 
  tincta 
  Grunow. 
  

  

  Chaetoceros 
  sp. 
  

  

  Grammatophora 
  marina 
  (Lyngby) 
  Kiitzing. 
  

  

  Licmophora 
  flabellata 
  (Carmichael) 
  Agardh. 
  

  

  Rhabdonema 
  arcuatum 
  Kiitzing. 
  

  

  Pleurosigma 
  sp. 
  

  

  Pleurosigma 
  fascicola 
  AV. 
  Smith. 
  

  

  