﻿[41] 
  A 
  SYSTEM 
  OF 
  OYSTER 
  CULTURE. 
  421 
  

  

  no 
  objection 
  to 
  naming 
  the 
  coloring 
  principle 
  absorbed 
  by 
  the 
  oyster 
  

   marennin; 
  and, 
  so 
  far 
  as 
  the 
  writer 
  can 
  discover, 
  this 
  is 
  Professor 
  Lan- 
  

   kester's 
  principal 
  contribution 
  to 
  the 
  subject, 
  aside 
  from 
  the 
  claim 
  made 
  

   for 
  the 
  existence 
  of 
  " 
  secretion 
  cells 
  " 
  in 
  the 
  epithelium 
  of 
  the 
  gills 
  and 
  

   palps. 
  The 
  existence 
  of 
  cells 
  with 
  the 
  function 
  ascribed 
  to 
  them 
  in 
  his 
  

   paper 
  is, 
  however, 
  rendered 
  even 
  more 
  doubtful 
  by 
  the 
  fact 
  that 
  some- 
  

   times 
  a 
  uniform 
  deep, 
  bluish-green 
  tint 
  becomes 
  apparent 
  not 
  only 
  in 
  the 
  

   epithelium 
  of 
  the 
  gills, 
  but 
  also 
  in 
  the 
  mantle, 
  throughout 
  which 
  the 
  

   color 
  may 
  be 
  nearly 
  uniform 
  or 
  irregularly 
  distributed 
  in 
  patches, 
  which 
  

   shade 
  off 
  imperceptibly 
  into 
  areas 
  not 
  affected. 
  

  

  The 
  fact 
  that 
  the 
  green 
  cells 
  found 
  by 
  me 
  in 
  the 
  ventricle 
  are 
  blood- 
  

   cells 
  admits 
  of 
  no 
  doubt, 
  as 
  I 
  was 
  careful 
  to 
  compare 
  them 
  with 
  the 
  

   colorless 
  blood-cells 
  of 
  uncolored 
  individuals. 
  That 
  they 
  are 
  quite 
  free 
  

   is 
  also 
  unquestionable, 
  as 
  they 
  would 
  immediately 
  separate 
  when 
  the 
  

   cysts 
  or 
  the 
  heart 
  in 
  which 
  they 
  were 
  contained 
  was 
  opened. 
  The 
  view 
  

   which 
  I 
  have 
  published 
  in 
  my 
  fourth 
  paper 
  on 
  the 
  clam 
  has 
  therefore 
  

   not 
  been 
  in 
  the 
  least 
  weakened 
  by 
  what 
  Professor 
  Lankester 
  has 
  pub- 
  

   lished; 
  and, 
  while 
  it 
  anticipates 
  him 
  by 
  several 
  months, 
  it 
  likewise, 
  I 
  

   think, 
  gives 
  a 
  far 
  more 
  probable 
  explanation 
  of 
  the 
  phenomenon. 
  

  

  I 
  might 
  also 
  add 
  that 
  Professor 
  Lankester's 
  spectroscopic 
  investiga- 
  

   tions 
  brought 
  him 
  to 
  about 
  the 
  same 
  results 
  as 
  were 
  reached 
  by 
  me 
  with 
  

   a 
  microspectroscope 
  in 
  1881. 
  

  

  Finally, 
  I 
  must 
  not 
  forget 
  to 
  mention 
  the 
  crucial 
  tests 
  made 
  by 
  MM. 
  

   Puysegur 
  and 
  Decaisne, 
  as 
  they 
  showed 
  that 
  the 
  coloration 
  could 
  be 
  

   imparted 
  to 
  oysters 
  at 
  will 
  by 
  simply 
  feeding 
  them 
  with 
  Navicula 
  os- 
  

   trearia. 
  They 
  also 
  proved 
  that 
  when 
  oysters 
  colored 
  in 
  that 
  way 
  were 
  

   deprived 
  of 
  the 
  kind 
  of 
  food 
  whence 
  the 
  color 
  was 
  derived, 
  in 
  a 
  short 
  

   time 
  Yliey 
  again 
  became 
  white-fleshed. 
  

  

  