﻿68 
  

  

  season 
  of 
  188(), 
  were 
  iiiiioh 
  more 
  satisfactory 
  with 
  lialf- 
  

   round 
  tiles. 
  Using 
  hurdles 
  or 
  nests 
  nimihering 
  8 
  to 
  16 
  

   tiles, 
  the 
  results 
  obtained 
  from 
  one 
  placed 
  in 
  the 
  Big 
  

   Annemessex 
  were 
  very 
  flattering. 
  After 
  it 
  had 
  been 
  im- 
  

   mersed 
  24 
  days 
  1506 
  oysters 
  were 
  counted 
  ; 
  after 
  4o 
  days 
  

   1334 
  ; 
  and 
  after 
  93 
  days 
  had 
  elapsed 
  the 
  number 
  still 
  

   adherent 
  was 
  o39. 
  In 
  size 
  and 
  at 
  corresponding 
  ages 
  

   these 
  were 
  similar 
  to 
  those 
  which 
  fixed 
  themselves 
  to 
  the 
  

   slates 
  used 
  at 
  St. 
  Jerome's. 
  From 
  what 
  we 
  know 
  of 
  the 
  

   numlier 
  which 
  sometimes 
  fix 
  themselves 
  to 
  a 
  single 
  (.)bject 
  

   we 
  may 
  yet 
  look 
  for 
  great 
  successes 
  in 
  tlie 
  use 
  of 
  collect- 
  

   ing 
  apparatus. 
  In 
  one 
  instance, 
  the 
  inner 
  face 
  of 
  one 
  

   valve 
  of 
  a 
  dead 
  oyster 
  furnished 
  attachment 
  for 
  over 
  40 
  

   spat 
  from 
  h 
  to 
  I 
  of 
  an 
  inch 
  in 
  diameter. 
  

  

  CHANCxES 
  OF 
  FORM 
  BUKINCi 
  THE 
  GKOAVTII 
  (»F 
  THE 
  SHELL. 
  

  

  N^D---A* 
  

  

  Figure 
  15. 
  

  

  In 
  Fig. 
  15 
  we 
  liave 
  attempted 
  to 
  represent 
  the 
  changes 
  

   of 
  shape 
  and 
  character 
  of 
  the 
  shell 
  of 
  the 
  oyster 
  in 
  pass- 
  

   ing 
  from 
  the 
  free-swimming 
  larval 
  condition 
  to 
  that 
  of 
  

   the 
  adult. 
  There 
  are 
  three 
  well 
  marked 
  stages 
  of 
  sliell- 
  

   growth. 
  viz. 
  : 
  (1) 
  the 
  perfectly 
  synmieti-ical 
  stage 
  attained 
  

   by 
  the 
  valves 
  of 
  the 
  "fry 
  ;'" 
  (2) 
  ^he 
  asymmetrical 
  stage 
  

   of 
  the 
  "spat,"" 
  and 
  (3) 
  tlie 
  asymmetrical 
  form 
  assumed 
  

   l)y 
  the 
  valves 
  of 
  the 
  adult. 
  In 
  the 
  figin-e, 
  wliich 
  is 
  sup- 
  

   posed 
  to 
  be 
  a 
  section 
  of 
  the 
  shell 
  with 
  all 
  its 
  parts 
  j>re- 
  

   served, 
  cut 
  through 
  lengthwise 
  from 
  the 
  hinge 
  end 
  to 
  the 
  

   free 
  edges 
  of 
  the 
  valves, 
  we 
  note 
  first, 
  that 
  the 
  shells 
  of 
  

   the 
  larva 
  or 
  "fry"" 
  In. 
  are 
  alike 
  in 
  cross-section 
  ; 
  that 
  the 
  

   section 
  of 
  the 
  "spat," 
  which 
  has 
  affixed 
  itself 
  to 
  a 
  sta- 
  

  

  