﻿14 
  

  

  very 
  rudimentary 
  in 
  the 
  oyster. 
  AVhen 
  oysters 
  are 
  

   removed 
  from 
  salt 
  water 
  to 
  that 
  which 
  is 
  less 
  salt, 
  a 
  

   similar 
  enlargement 
  of 
  the 
  animal 
  takes 
  place, 
  which 
  

   may 
  be 
  entirely 
  attributed 
  to 
  the 
  effect 
  of 
  the 
  action 
  of 
  

   the 
  well-known 
  laws 
  of 
  osmosis, 
  and 
  should 
  not 
  be 
  re- 
  

   garded 
  as 
  a 
  fattening 
  process 
  at 
  all, 
  since 
  the 
  real 
  "fat" 
  

   of 
  the 
  oyster 
  is 
  [something 
  vastly 
  more 
  substantial 
  than 
  

   water, 
  as 
  will 
  be 
  learned 
  in 
  the 
  sequel. 
  Prof. 
  P. 
  Frazer, 
  

   Jr.,* 
  has 
  discussed 
  the 
  subject 
  of 
  fattening 
  oysters 
  by 
  

   means 
  of 
  osmosis. 
  

  

  For 
  my 
  own 
  part 
  I 
  believe 
  that 
  the 
  turgid, 
  translucent 
  

   appearance^of 
  the 
  edges 
  of 
  the 
  mantle 
  in 
  the 
  oyster 
  is 
  

   due 
  to 
  the 
  passage 
  inwards 
  of 
  water 
  through 
  the 
  mouths 
  

   of 
  numerous 
  vessels 
  which 
  ox^en 
  freely 
  on 
  its 
  surface 
  ; 
  

   these 
  from 
  my 
  microscopic 
  examinations 
  seemed 
  to 
  be 
  

   the 
  extremities 
  of 
  the 
  capillaries 
  of 
  the 
  mantle, 
  and 
  I 
  

   find 
  that 
  for 
  this 
  belief 
  I 
  liave 
  the 
  concurrent 
  testimony 
  

   of 
  other 
  writers, 
  (Bronn 
  ; 
  Klass. 
  u. 
  Ord. 
  Ill, 
  384.) 
  

  

  The 
  nervous 
  system 
  of 
  the 
  oyster 
  is 
  very 
  simple, 
  being 
  

   composed 
  of 
  a 
  pair 
  of 
  ganglia 
  or 
  masses 
  of 
  nervous 
  mat- 
  

   ter, 
  which 
  lie 
  just 
  over 
  the 
  gullet, 
  and 
  from 
  which 
  a 
  pair 
  

   of 
  nerve 
  cords 
  pass 
  backwards, 
  one 
  on 
  each 
  side, 
  to 
  join 
  

   the 
  hinder 
  pair 
  which 
  lie 
  just 
  beneath 
  the 
  adductor 
  

   muscle. 
  The 
  mantle 
  receives 
  nerve 
  branches 
  from 
  the 
  

   hindmost 
  ganglia, 
  and 
  these 
  control 
  the 
  contraction 
  and 
  

   elongation 
  of 
  the 
  radiating 
  bundles 
  of 
  muscular 
  fibers 
  as 
  

   well 
  as 
  those 
  which 
  lie 
  lengtlnvise 
  along 
  the 
  margin 
  ; 
  the 
  

   former 
  contract 
  and 
  withdraw 
  the 
  edges 
  of 
  the 
  mantle 
  

   from 
  the 
  margin 
  of 
  the 
  shell, 
  while 
  the 
  latter 
  in 
  con- 
  

   tracting 
  tend 
  to 
  crimp 
  or 
  fold 
  its 
  edges. 
  The 
  tentacles, 
  

   or 
  organs 
  of 
  touch, 
  are 
  also 
  mainly 
  supplied 
  from 
  the 
  

   hindmost 
  ganglia, 
  while 
  the 
  internal 
  organs 
  are 
  inner- 
  

   vated 
  from 
  the 
  head 
  ganglia. 
  

  

  *0n 
  Dialysis 
  in 
  Oyster 
  Culture. 
  Proc. 
  Acad. 
  Nat. 
  Sciences, 
  27. 
  1875, 
  pp. 
  442 
  — 
  43. 
  

  

  