﻿178 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  dislodged 
  in 
  the 
  process 
  of 
  extracting 
  the 
  appendages, 
  particularly 
  if 
  

   the 
  struggle 
  is 
  prolonged, 
  and 
  become 
  attached 
  to 
  the 
  bristles 
  or 
  hairs 
  

   of 
  the 
  clean 
  appendages. 
  Frequently 
  the 
  number 
  thus 
  attached 
  is 
  

   large. 
  

  

  RATE 
  OF 
  GROWTH 
  OF 
  THE 
  DIATOMS 
  ON 
  THE 
  FRY. 
  

  

  As 
  soon 
  as 
  a 
  lodgment 
  is 
  obtained 
  upon 
  the 
  lobster 
  the 
  diatoms 
  

   begin 
  their 
  active 
  growth 
  and 
  soon 
  spread 
  over 
  the 
  whole 
  body. 
  Even 
  

   a 
  few 
  hours 
  after 
  molting 
  the 
  fry 
  may 
  be 
  badly 
  infested 
  and 
  within 
  

   two 
  days 
  are 
  so 
  covered 
  with 
  diatoms 
  that 
  they 
  appear 
  shaggy 
  to 
  the 
  

   naked 
  eye. 
  Fry 
  that 
  molt 
  become 
  covered 
  again 
  within 
  the 
  same 
  

   length 
  of 
  time. 
  Figures 
  3 
  and 
  4 
  of 
  plate 
  y 
  show 
  the 
  amount 
  of 
  growth 
  

   that 
  may 
  take 
  place 
  in 
  48 
  hours. 
  

  

  SOURCE 
  OF 
  THE 
  DIATOMS 
  — 
  THEIR 
  NATURAL 
  HABITAT. 
  

  

  From 
  the 
  fact 
  that 
  the 
  diatoms 
  are 
  not 
  present 
  on 
  the 
  eggs 
  while 
  

   still 
  attached 
  to 
  the 
  female 
  and 
  that 
  they 
  appear 
  immediately 
  in 
  the 
  

   hatching 
  jars, 
  we 
  are 
  led 
  to 
  suppose 
  that 
  they 
  are 
  present 
  in 
  the 
  water 
  

   when 
  pumped 
  through 
  the 
  pipes 
  to 
  the 
  hatchery, 
  and 
  that 
  perhaps 
  they 
  

   grow 
  on 
  the 
  inside 
  of 
  the 
  pipes 
  or 
  hatching 
  jars. 
  

  

  Diatoms 
  in 
  the 
  water 
  jMmped 
  to 
  the 
  hatchery. 
  — 
  A 
  quantity 
  of 
  water 
  

   as 
  it 
  flowed 
  from 
  the 
  supply 
  pipe 
  leading 
  to 
  the 
  hatching 
  jars 
  was 
  fil- 
  

   tered 
  and 
  an 
  examination 
  made 
  of 
  the 
  material 
  collected 
  by 
  the 
  filter. 
  

   The 
  diatom 
  Licmophora 
  tincta 
  was 
  pi'esent 
  in 
  considerable 
  numbers 
  

   and 
  with 
  it 
  were 
  the 
  following 
  species, 
  though 
  much 
  less 
  abundant:. 
  

   Tabellaria 
  {Striatella) 
  xinipunGtata., 
  Licmophora 
  flahellata^ 
  Navicida^ 
  

   (two 
  species), 
  Pleurosigma 
  sp. 
  There 
  were 
  present, 
  also, 
  some 
  algal 
  

   filaments, 
  Vorticella, 
  and 
  fragments 
  of 
  copepods, 
  isopods, 
  and 
  amphi- 
  

   pods 
  {CapreUa 
  geoinetrica). 
  

  

  The 
  spores 
  of 
  these 
  diatoms 
  are 
  so 
  small 
  that 
  they 
  can 
  not 
  be 
  detected 
  

   by 
  direct 
  microscopic 
  examination, 
  and 
  the 
  sessile 
  varieties 
  of 
  diatoms, 
  

   those 
  present 
  on 
  the 
  lobsters, 
  do 
  not 
  grow 
  in 
  ordinary 
  water 
  cultures. 
  

   It 
  was 
  therefore 
  difficult 
  to 
  demonstrate 
  the 
  presence 
  of 
  spores 
  in 
  

   the 
  water, 
  but 
  the 
  fact 
  that 
  they 
  are 
  given 
  off 
  in 
  large 
  numbers 
  during 
  

   certain 
  stages 
  of 
  the 
  growth 
  of 
  diatoms 
  makes 
  their 
  presence 
  highly 
  

   probable. 
  

  

  On 
  the 
  inside 
  of 
  the 
  hatching 
  jars 
  and 
  on 
  the 
  glass 
  tubes 
  that 
  carry 
  

   water 
  to 
  the 
  bottoms 
  of 
  the 
  jars, 
  there 
  is 
  almost 
  always 
  a 
  growth 
  

   of 
  alg», 
  and 
  on 
  the 
  filaments 
  of 
  the 
  algje 
  there 
  is 
  usually 
  a 
  growth 
  of 
  

   diatoms. 
  As 
  far 
  as 
  observed 
  these 
  diatoms 
  were 
  all 
  of 
  one 
  species, 
  

   Diatoma 
  hyalinum. 
  Licmophora 
  tincta 
  was 
  never 
  found 
  growing 
  

   there. 
  

  

  Diatoms 
  in 
  water 
  outside 
  of 
  hatchery.— 
  During 
  September, 
  1902, 
  a 
  

   series 
  of 
  observations 
  was 
  made 
  to 
  determine 
  the 
  presence 
  of 
  diatoms 
  

   in 
  the 
  water 
  outside 
  of 
  the 
  hatcher}'. 
  In 
  the 
  tow 
  collected 
  on 
  several 
  

  

  