﻿EPITHELIAL 
  ISLETS 
  OF 
  THE 
  PANCREAS 
  IN 
  TELEOSTET. 
  389 
  

  

  Although 
  some 
  of 
  the 
  material 
  examined 
  by 
  me 
  might 
  be 
  

   interpreted 
  similarly 
  (e.g.iu 
  Zeus 
  faber) 
  in 
  several 
  instances, 
  

   of 
  which 
  I 
  give 
  a 
  detailed 
  account, 
  the 
  contrast 
  in 
  size, 
  

   form, 
  structure, 
  arrangement, 
  and 
  relation 
  to 
  the 
  capillaries 
  

   of 
  the 
  cells 
  of 
  the 
  two 
  regions 
  o£ 
  the 
  islet, 
  as 
  well 
  as 
  their 
  

   different 
  staiuing 
  capacities, 
  appear 
  to 
  me 
  so 
  marked 
  that 
  

   I 
  am 
  not 
  prepared 
  to 
  accept 
  Diamare's 
  explanation 
  as 
  

   satisfactory. 
  

  

  In 
  the 
  descriptions 
  which 
  follow 
  I 
  have 
  not 
  considered 
  it 
  

   necessary 
  to 
  detail 
  the 
  appearances 
  in 
  each 
  of 
  the 
  species 
  

   already 
  enumerated 
  ; 
  I 
  have 
  selected 
  such 
  as 
  together 
  illus- 
  

   trate 
  fully 
  the 
  essential 
  structure 
  of 
  these 
  bodies 
  as 
  a 
  whole, 
  

  

  Zeus 
  faber. 
  — 
  In 
  this 
  species, 
  apart 
  from 
  a 
  slightly 
  less 
  

   intimate 
  relation 
  of 
  islet 
  and 
  acini 
  in 
  the 
  case 
  of 
  the 
  principal 
  

   as 
  compared 
  with 
  the 
  others, 
  the 
  histological 
  structure 
  of 
  

   these 
  bodies 
  is 
  similar 
  in 
  every 
  respect. 
  They 
  are 
  fairly 
  

   numerous 
  in 
  the 
  intercoecal 
  pancreatic 
  masses, 
  where 
  they 
  lie 
  

   close 
  to 
  the 
  zymogenous 
  tissue, 
  and 
  are 
  without 
  any 
  special 
  

   capsule. 
  Some 
  are 
  of 
  distinctly 
  irregular 
  outline. 
  They 
  

   consist 
  of 
  polyhedral 
  cells, 
  smaller 
  than 
  the 
  cells 
  of 
  the 
  

   pancreas 
  ; 
  their 
  walls 
  are 
  well 
  defined, 
  and 
  the 
  cytoplasm 
  

   exhibits 
  a 
  delicate 
  meshwork 
  of 
  fibrils. 
  The 
  nuclei 
  are 
  

   irregularly 
  circular 
  or 
  oval, 
  and 
  show 
  a 
  large 
  nucleolus 
  

   which 
  always 
  stained 
  a 
  dark 
  red. 
  Chromatin 
  net-knots 
  were 
  

   always 
  observed, 
  as 
  also 
  the 
  nuclear 
  membrane. 
  Apart 
  from 
  

   size 
  and 
  the 
  possession 
  of 
  a 
  capsule 
  of 
  areolar 
  tissue 
  which 
  

   may 
  send 
  in 
  supporting 
  partitions, 
  the 
  principal 
  islet 
  exhibits 
  

   the 
  same 
  structure 
  as 
  the 
  others. 
  The 
  pancreatic 
  acini, 
  

   however, 
  in 
  the 
  examples 
  sectioned, 
  did 
  not 
  completely 
  en- 
  

   velop 
  the 
  islet. 
  

  

  The 
  differently 
  staining 
  patches 
  already 
  spoken 
  of 
  were 
  

   usually 
  observable 
  in 
  preparations 
  of 
  islets 
  from 
  this 
  species. 
  

   Examination 
  with 
  high 
  powers 
  showed 
  that 
  this 
  difference 
  is 
  

   due 
  mainly, 
  though 
  not 
  altogether, 
  to 
  the 
  staining* 
  capacity 
  

   of 
  the 
  nuclei 
  in 
  the 
  respective 
  areas. 
  The 
  chromatin 
  is 
  

   more 
  abundant 
  in 
  the 
  nuclei 
  which 
  stain 
  more 
  darkly. 
  At 
  

   the 
  same 
  time, 
  the 
  cytoplasm 
  of 
  these 
  cells 
  appears 
  to 
  take 
  

  

  