﻿394 
  JOHN 
  RENNIE. 
  

  

  certain 
  structural 
  differences 
  were 
  made 
  out 
  with 
  high 
  

   powers. 
  

  

  1. 
  The 
  form 
  of 
  the 
  cell. 
  In 
  the 
  darkly 
  staining 
  strands 
  

   this 
  was 
  seen 
  to 
  be 
  always 
  more 
  or 
  less 
  columnar, 
  and 
  was 
  

   probably 
  due 
  to 
  their 
  position 
  and 
  arrangement 
  between 
  the 
  

   capillaries. 
  The 
  cell-walls 
  could 
  not 
  be 
  made 
  out 
  clearly. 
  

   The 
  lightly 
  staining 
  cells 
  are 
  irregularly 
  polyhedral, 
  their 
  

   walls 
  could 
  usually 
  be 
  traced 
  with 
  distinctness, 
  and 
  they 
  are 
  

   evidently 
  larger 
  than 
  the 
  columnar 
  types. 
  

  

  2. 
  The 
  appearance 
  of 
  the 
  cytoplasm. 
  In 
  the 
  columnar 
  

   types 
  this 
  appeared 
  diffusely 
  and 
  finely 
  granular. 
  The 
  light 
  

   cells 
  showed 
  a 
  fairly 
  open 
  network 
  of 
  fibrils. 
  

  

  3. 
  The 
  nuclei. 
  In 
  the 
  columnar 
  cells 
  these 
  appeared 
  

   regularly 
  ovoid 
  or 
  spherical, 
  and 
  smaller 
  than 
  those 
  of 
  the 
  

   polyhedral 
  type. 
  These 
  latter 
  were 
  very 
  variable 
  and 
  very 
  

   irregular 
  in 
  outline. 
  Both 
  kinds 
  showed 
  nucleoli 
  and 
  net- 
  

   knots, 
  the 
  polyhedral 
  cells 
  showing 
  these 
  very 
  clearly. 
  

   Regarding 
  those 
  nuclear 
  differences, 
  I 
  do 
  not 
  think 
  they 
  can 
  

   be 
  attributed 
  to 
  fixatives, 
  since 
  the 
  irregular 
  forms 
  were 
  found 
  

   only 
  among 
  the 
  polyhedral 
  cells. 
  

  

  In 
  Hippoglossus 
  vulgaris 
  the 
  conditions 
  are 
  similar 
  to 
  

   those 
  described 
  for 
  Pleuronectes. 
  

  

  In 
  the 
  Gadidse 
  only 
  small 
  islets 
  were 
  examined, 
  and 
  in 
  

   these 
  no 
  special 
  features 
  were 
  observed. 
  The 
  cells 
  were 
  all 
  

   of 
  one 
  type, 
  and 
  similar 
  to 
  those 
  of 
  the 
  lightly 
  staining 
  areas 
  

   of 
  those 
  forms 
  exhibiting 
  two 
  types. 
  The 
  islets 
  were 
  com- 
  

   pletely 
  surrounded 
  by 
  pancreatic 
  tissue, 
  and 
  no 
  capsule 
  was 
  

   present. 
  

  

  Lophobranchii. 
  — 
  Examples 
  of 
  three 
  different 
  genera 
  of 
  

   this 
  group 
  were 
  examined. 
  A 
  principal 
  islet 
  only 
  was 
  found, 
  

   and 
  this 
  was 
  sectioned 
  in 
  each 
  case. 
  There 
  is 
  a 
  distinct 
  

   limiting 
  capsule, 
  which 
  may 
  be 
  pigmented, 
  of 
  a 
  different 
  

   tissue 
  from 
  that 
  supporting 
  the 
  pancreatic 
  acini. 
  These 
  latter 
  

   are 
  quite 
  apart 
  from 
  the 
  islet, 
  and 
  in 
  fact 
  are 
  more 
  closely 
  

   associated 
  with 
  the 
  mesenteric 
  blood-vessels 
  than 
  with 
  this 
  

   body. 
  Capillaries 
  are 
  numerous, 
  but 
  I 
  did 
  not 
  find 
  the 
  cells 
  

   arranged 
  in 
  columns 
  around 
  these, 
  nor 
  did 
  I 
  find 
  two 
  types 
  of 
  

  

  