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  REPOET 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

  

  Further 
  experiments 
  were 
  not 
  tried 
  at 
  Woods 
  Hole, 
  but 
  at 
  Wick- 
  

   ford 
  some 
  observations 
  were 
  made 
  bearing 
  on 
  this 
  point. 
  During 
  the 
  

   summer 
  of 
  1901 
  an 
  awning 
  shaded 
  all 
  the 
  bags 
  in 
  which 
  the 
  lobster 
  

   fry 
  were 
  reared. 
  This 
  awning 
  was 
  about 
  9 
  feet 
  above 
  the 
  water, 
  so 
  

   that 
  while 
  the 
  direct 
  sunlight 
  was 
  excluded 
  there 
  was 
  a 
  consideral)le 
  

   amount 
  of 
  diffused 
  light. 
  During 
  this 
  summer 
  there 
  was 
  very 
  little 
  

   trouble 
  from 
  diatoms. 
  In 
  1902 
  the 
  awning 
  was 
  not 
  used 
  and 
  there 
  

   was 
  a 
  very 
  abundant 
  growth 
  of 
  diatoms. 
  It 
  ma}^ 
  be 
  that 
  some 
  other 
  

   condition 
  had 
  something 
  to 
  do 
  with 
  this 
  result, 
  but 
  it 
  seems 
  very 
  cer- 
  

   tain 
  that, 
  although 
  the 
  exclusion 
  of 
  the 
  greater 
  part 
  of 
  the 
  light 
  may 
  

   be 
  injurious 
  to 
  the 
  fry 
  as 
  well 
  as 
  to 
  the 
  diatoms, 
  a 
  cutting 
  off 
  of 
  the 
  

   direct 
  sunlight, 
  without 
  excessive 
  shading, 
  is 
  an 
  important 
  factor 
  to 
  

   be 
  considered 
  in 
  all 
  attempts 
  to 
  get 
  rid 
  of 
  the 
  great 
  abundance 
  of 
  

   diatomaceous 
  growth 
  that 
  ordinarily 
  occurs. 
  

  

  Hastening 
  the 
  development 
  of 
  the 
  fry. 
  — 
  The 
  last 
  and 
  perhaps 
  the 
  

   most 
  promising 
  remedy 
  that 
  suggests 
  itself 
  is 
  to 
  hasten 
  the 
  develop- 
  

   ment 
  of 
  the 
  fry. 
  A 
  rapid 
  series 
  of 
  molts 
  prevents 
  the 
  excessive 
  

   growth 
  of 
  the 
  diatoms. 
  If 
  by 
  means 
  of 
  proper 
  care 
  and 
  proper 
  feed- 
  

   ing 
  the 
  fry 
  can 
  be 
  so 
  hastened 
  through 
  their 
  early 
  stages 
  that 
  the 
  

   diatoms 
  have 
  no 
  chance 
  to 
  develop 
  to 
  an 
  injurious 
  extent, 
  the 
  problem 
  

   is 
  solved 
  in 
  the 
  most 
  advantageous 
  way. 
  This 
  economy 
  of 
  time 
  will 
  

   be 
  felt 
  not 
  only 
  because 
  of 
  its 
  influence 
  on 
  the 
  growth 
  of 
  diatoms 
  but 
  

   also 
  in 
  the 
  running 
  of 
  the 
  apparatus 
  and 
  in 
  the 
  attention 
  of 
  those 
  

   employed 
  to 
  care 
  for 
  the 
  fry. 
  

  

  The 
  principal 
  factors 
  on 
  which 
  depend 
  the 
  rapidity 
  of 
  growth 
  and 
  the 
  

   freqency 
  of 
  molting 
  are 
  temperature 
  and 
  food. 
  Dr. 
  A. 
  D. 
  Mead, 
  of 
  

   the 
  Rhode 
  Island 
  tish 
  commission, 
  seems 
  to 
  think 
  that 
  the 
  temperature 
  

   is 
  the 
  most 
  important 
  factor, 
  as 
  will 
  be 
  seen 
  from 
  the 
  following 
  state- 
  

   ment 
  by 
  him 
  in 
  the 
  Report 
  of 
  the 
  Rhode 
  Island 
  Fish 
  Commission 
  for 
  

   1901: 
  

  

  The 
  average 
  period 
  between 
  hatching 
  and 
  reaching 
  tiie 
  fourth 
  stage 
  for 
  the 
  entire 
  

   eleven 
  experiments 
  at 
  Wickford 
  was 
  a 
  little 
  over 
  12 
  days. 
  In 
  each 
  experiment 
  

   the 
  average 
  duration 
  of 
  the 
  first 
  three 
  stages 
  varied 
  from 
  9 
  to 
  16 
  days. 
  In 
  

   experiments 
  conducted 
  at 
  Woods 
  Hole 
  the 
  time 
  required 
  for 
  these 
  molts 
  was 
  con- 
  

   siderably 
  greater; 
  of 
  the 
  first 
  lot, 
  hatched 
  May 
  23, 
  the 
  fourth 
  stage 
  was 
  reached 
  by 
  a 
  

   few 
  only 
  on 
  June 
  12, 
  after 
  an 
  interval 
  of 
  20 
  days. 
  Indeed, 
  on 
  the 
  twelfth 
  day 
  

   (the 
  average 
  time 
  of 
  reaching 
  the 
  fourth 
  stage 
  at 
  Wickford) 
  none 
  had 
  reached 
  even 
  

   the 
  third 
  stage 
  at 
  Woods 
  Hole. 
  The 
  explanation 
  of 
  the 
  variations 
  in 
  the 
  length 
  of 
  

   time 
  required 
  for 
  the 
  first 
  three 
  stages 
  probably 
  lies 
  in 
  the 
  differences 
  of 
  temperature 
  

   of 
  the 
  water 
  — 
  the 
  colder 
  the 
  water 
  the 
  slower 
  the 
  development. 
  

  

  It 
  is 
  not 
  possible 
  to 
  say 
  at 
  present 
  that 
  the 
  variations 
  in 
  the 
  length 
  of 
  the 
  early 
  

   stages 
  are 
  due 
  entirely 
  to 
  the 
  differences 
  in 
  temperature, 
  and 
  it 
  may 
  be 
  that 
  other 
  

   factors 
  have 
  more 
  or 
  less 
  influence: 
  but 
  it 
  is 
  extremely 
  probable 
  that 
  temperature 
  is 
  

   the 
  main 
  factor. 
  

  

  