﻿EPITHELIAL 
  ISLETS 
  OF 
  THE 
  PANCREAS 
  IN 
  TELEOSTEI. 
  393 
  

  

  contrast 
  between 
  the 
  two 
  was 
  in 
  fact 
  marked. 
  The 
  darkly 
  

   staining 
  cells 
  were 
  columnar, 
  with 
  finely 
  granular 
  cytoplasm 
  ; 
  

   imclei 
  almost 
  uniformly 
  oval 
  with 
  a 
  distinct 
  nucleolus 
  and 
  

   granular 
  chromatin. 
  The 
  lighter 
  staining 
  cells 
  were 
  irregu- 
  

   larly 
  polygonal, 
  their 
  cytoplasm 
  not 
  so 
  granular, 
  and 
  their 
  

   nuclei 
  of 
  very 
  irregular 
  outline. 
  A 
  few 
  of 
  these 
  are 
  given 
  

   in 
  fig. 
  7. 
  A 
  frequent 
  form 
  is 
  that 
  with 
  a 
  deep 
  cleft 
  

   between 
  two 
  portions. 
  There 
  are 
  fine 
  fibrils 
  of 
  chromatin 
  

   with 
  net-knots 
  and 
  also 
  distinct 
  nucleolus 
  visible. 
  The 
  

   contrast 
  here 
  is 
  very 
  different 
  from 
  the 
  appearance 
  in 
  Zeus, 
  

   and 
  I 
  do 
  not 
  think 
  can 
  reasonably 
  be 
  attributed 
  to 
  differences 
  

   in 
  functional 
  state 
  of 
  the 
  same 
  kind 
  o£ 
  cell. 
  They 
  appear 
  to 
  

   me 
  to 
  constitute 
  two 
  interlacing 
  tissues. 
  

  

  Pleuronectes 
  platessa 
  (figs. 
  8 
  and 
  9). 
  — 
  The 
  principal 
  

   islet 
  lies 
  within 
  a 
  small 
  mass 
  of 
  pancreas 
  which 
  is 
  attached 
  to 
  

   the 
  gall-bladder. 
  The 
  greater 
  part 
  of 
  this 
  mass, 
  which 
  is 
  that 
  

   spoken 
  of 
  by 
  Cole 
  and 
  Johnstone 
  (1) 
  as 
  a 
  " 
  little 
  nodular 
  

   swelling,'' 
  consists 
  of 
  islet 
  ; 
  the 
  zymogenous 
  tissue 
  forms 
  a 
  

   small 
  envelope 
  around 
  it. 
  There 
  is 
  a 
  definite 
  capsule, 
  but 
  I 
  

   did 
  not 
  see 
  any 
  supporting 
  trabeculte. 
  It 
  is 
  usually 
  pene- 
  

   trated 
  by 
  zj'-mogenous 
  elements, 
  and 
  where 
  this 
  is 
  so, 
  con- 
  

   nective 
  tissue 
  surrounds 
  these 
  and 
  separates 
  them 
  from 
  the 
  

   islet 
  tissue. 
  This 
  penetration 
  by 
  pancreatic 
  tissue 
  is 
  a 
  feature 
  

   which 
  has 
  already 
  been 
  noted 
  in 
  other 
  instances, 
  and, 
  as 
  in 
  

   those 
  cases, 
  it 
  was 
  here 
  traceable 
  as 
  continuous 
  with 
  the 
  same 
  

   elements 
  around 
  the 
  capsule. 
  The 
  components 
  of 
  the 
  islet 
  are 
  

   very 
  small 
  cells 
  richly 
  supplied 
  with 
  capillaries. 
  The 
  capil- 
  

   laries 
  are 
  not 
  equally 
  distributed 
  throughout, 
  but 
  are 
  more 
  

   abundant 
  in 
  the 
  inner 
  regions. 
  In 
  these 
  parts 
  the 
  cells 
  

   occur 
  in 
  columns 
  or 
  strands 
  having 
  a 
  somewhat 
  sinuous 
  

   arrangement; 
  they 
  evidently 
  in 
  many 
  instances 
  surround 
  and 
  

   follow 
  the 
  course 
  of 
  the 
  capillaries. 
  These 
  cells 
  stain 
  darkly. 
  

   In 
  the 
  spaces 
  between 
  these 
  winding 
  strands, 
  and 
  also 
  in 
  

   other 
  parts 
  of 
  the 
  islet, 
  where, 
  as 
  already 
  indicated, 
  the 
  

   capillaries 
  are 
  not 
  so 
  numerous, 
  cells, 
  lightly 
  staining, 
  are 
  

   massed. 
  The 
  arrangement 
  is 
  quite 
  different, 
  but 
  besides 
  a 
  

   difference 
  in 
  staining 
  capacity 
  and 
  relation 
  to 
  the 
  capillaries, 
  

  

  