﻿OYSTEK 
  mDUSTBY 
  OF 
  NORTH 
  CAKOHNA. 
  338 
  

  

  probable 
  that 
  many 
  of 
  them, 
  whether 
  underfed 
  or 
  not, 
  succumb. 
  In 
  

   the 
  winter, 
  also, 
  exposure 
  to 
  too 
  low 
  a 
  temperature 
  may 
  freeze 
  them 
  to 
  

   death. 
  These 
  unfavorable 
  temperatures 
  surely 
  occur 
  with 
  sufficient 
  

   frequency 
  to 
  account 
  in 
  part 
  for 
  the 
  g-reat 
  quantities 
  of 
  empty 
  shells. 
  

  

  EXPERIMENTS. 
  

  

  I. 
  To 
  ascertain 
  tvhetJter 
  normal 
  oyster's 
  can 
  he 
  converted 
  into 
  elongated 
  

   ones 
  l)y 
  p'ressiire. 
  

  

  Thirty 
  round, 
  well-shaped 
  young 
  03'sters 
  were 
  removed 
  from 
  cultch 
  

   taken 
  from 
  the 
  experimental 
  bed 
  in 
  Newport 
  River. 
  These 
  oysters 
  

   were 
  fastened 
  by 
  means 
  of 
  Portland 
  cement 
  to 
  slabs 
  of 
  slate 
  and 
  the 
  

   cement 
  was 
  so 
  piled 
  up 
  around 
  them 
  that 
  each 
  oyster 
  was 
  subject 
  to 
  

   pressure 
  on 
  two 
  of 
  its 
  edges, 
  the 
  marg-in 
  opposite 
  the 
  hinge 
  being 
  free. 
  

   After 
  the 
  cement 
  had 
  hardened, 
  the 
  slabs 
  were 
  put 
  in 
  the 
  water 
  near 
  

   the 
  laboratory 
  and 
  left 
  undisturbed 
  for 
  one 
  month. 
  At 
  the 
  end 
  of 
  

   this 
  time 
  they 
  were 
  removed 
  and 
  the 
  oj^sters 
  examined. 
  

  

  None 
  had 
  died, 
  indicating 
  that 
  the 
  abnormal 
  conditions 
  under 
  which 
  

   they 
  had 
  been 
  placed 
  were 
  not 
  unfavorable 
  to 
  life. 
  None 
  had 
  grown 
  

   in 
  width, 
  but 
  all 
  were 
  longer 
  than 
  at 
  the 
  beginning. 
  Some 
  had 
  the 
  

   scolloped 
  anterior 
  edges 
  characteristic 
  of 
  elongated 
  oysters, 
  and 
  due 
  

   probably 
  to 
  the 
  fact 
  that 
  the 
  laterally 
  oppressed 
  mantles, 
  instead 
  of 
  

   spreading 
  out 
  flat 
  and 
  evenly, 
  are 
  thrown 
  into 
  folds. 
  These 
  results 
  

   indicate 
  that 
  mechanical 
  pressure 
  may 
  be 
  an 
  important 
  factor 
  in 
  deter- 
  

   mining 
  the 
  shape 
  of 
  the 
  shell. 
  

  

  II. 
  To 
  ascertain 
  vjJiether 
  elongated 
  oysters 
  liherated 
  from 
  an 
  oj)2)res- 
  

   sive 
  environment 
  will 
  change 
  in 
  shajye. 
  

  

  Thirty-five 
  elongated 
  and 
  narrow 
  young 
  03'sters 
  were 
  removed 
  from 
  

   their 
  crowded 
  condition, 
  cleaned, 
  and 
  carefully 
  measured. 
  Their 
  

   length 
  was 
  taken 
  from 
  the 
  tip 
  of 
  the 
  umbo 
  of 
  the 
  upper 
  valve 
  to 
  the 
  

   middle 
  of 
  the 
  anterior 
  edge, 
  and 
  their 
  width 
  at 
  a 
  point 
  on 
  the 
  same 
  

   valve 
  halfway 
  between 
  the 
  two 
  extremities 
  of 
  the 
  first 
  measurement. 
  

   They 
  were 
  then 
  placed 
  in 
  a 
  cage 
  made 
  of 
  galvanized 
  iron 
  wire, 
  and 
  

   this 
  was 
  suspended 
  horizontally 
  in 
  the 
  water 
  under 
  the 
  laboratory 
  

   wharf, 
  where 
  an 
  especially 
  strong 
  tidal 
  current 
  prevails. 
  Aft6r 
  

   thirty, 
  and 
  again 
  after 
  fortj^-eight, 
  days 
  the 
  above 
  measurements 
  were 
  

   taken 
  in 
  the 
  same 
  way 
  and 
  compared 
  with 
  the 
  initial 
  figures. 
  The 
  

   results 
  are 
  given 
  in 
  the 
  table 
  following. 
  

  

  