﻿EPITHELIAL 
  ISLETS 
  OP 
  THE 
  PANCREAS 
  IN 
  TELEOSTEI. 
  391 
  

  

  snrroundiiig 
  zymogenous 
  elements, 
  which 
  were 
  here 
  massed 
  

   and 
  not 
  spread 
  out 
  in 
  a 
  thin 
  sheet 
  as 
  is 
  more 
  common 
  in 
  

   small 
  fishes. 
  Here, 
  again, 
  darkly 
  and 
  lightly 
  staining 
  patches 
  

   of 
  irregular 
  outline 
  were 
  present, 
  whose 
  cells 
  exhibited 
  

   differences 
  in 
  arrangement 
  and 
  structure. 
  No 
  cell-walls 
  

   were 
  seen 
  in 
  the 
  case 
  of 
  the 
  darkly 
  staining 
  elements 
  ; 
  but, 
  

   from 
  the 
  very 
  close 
  arrangement 
  of 
  the 
  nuclei, 
  if 
  walls 
  were 
  

   pi'esent 
  the 
  cells 
  must 
  have 
  been 
  of 
  an 
  elongated 
  fusiform 
  

   type. 
  These 
  cells 
  are 
  arranged 
  in 
  bands 
  between 
  the 
  

   capillaries, 
  and 
  one 
  could 
  count 
  half 
  a 
  dozen 
  nuclei 
  on 
  an 
  

   average 
  in 
  a 
  row 
  across 
  a 
  band 
  between 
  two 
  capillaries. 
  No 
  

   network 
  could 
  be 
  made 
  out 
  in 
  the 
  cytoplasm 
  ; 
  the 
  nuclear 
  

   details 
  were 
  similar 
  to 
  those 
  already 
  given. 
  These 
  bands 
  

   were 
  not 
  so 
  definite 
  in 
  some 
  parts 
  as 
  in 
  others, 
  and 
  the 
  arrange- 
  

   ment 
  resembles 
  more 
  the 
  irregular 
  grouping 
  characteristic 
  

   of 
  the 
  lighter 
  staining 
  areas 
  of 
  the 
  islet. 
  Although 
  this 
  was 
  

   the 
  case, 
  it 
  was 
  noticeable 
  that 
  the 
  nuclei 
  of 
  the 
  irregularly 
  

   arranged 
  dark 
  cells 
  were 
  more 
  numerous 
  than 
  those 
  of 
  the 
  

   light 
  and 
  also 
  more 
  crowded 
  together. 
  The 
  lightly 
  staining 
  

   patches 
  showed 
  a 
  more 
  open 
  appearauce 
  owing 
  to 
  the 
  cells 
  

   being 
  larger 
  ; 
  they 
  were 
  seen 
  to 
  be 
  polyhedral 
  in 
  form. 
  The 
  

   nuclei 
  did 
  not 
  differ 
  much 
  from 
  those 
  of 
  the 
  dark 
  areas 
  (fig. 
  

   13). 
  In 
  Cyclopterus 
  lumpus 
  the 
  tissue 
  of 
  the 
  principal 
  

   islet 
  is 
  in 
  every 
  way 
  similar 
  to 
  that 
  here 
  described. 
  There 
  is, 
  

   however, 
  a 
  capsule 
  around 
  the 
  body, 
  outside 
  of 
  which 
  a 
  slight 
  

   layer 
  of 
  pancreatic 
  tissue 
  is 
  present. 
  

  

  Lophius 
  piscatorius. 
  — 
  The 
  islets 
  are 
  surrounded 
  by 
  a 
  

   capsule 
  of 
  rather 
  open 
  areolar 
  tissue. 
  In 
  those 
  examined 
  I 
  

   observed 
  no 
  indication 
  of 
  an 
  arrangement 
  of 
  the 
  cells 
  in 
  

   bands 
  as 
  is 
  apparent 
  in 
  many 
  species 
  ; 
  the 
  tissue 
  was 
  quite 
  

   uniform. 
  Capillaries 
  appeared 
  abundant, 
  and 
  in 
  the 
  con- 
  

   nective 
  tissue 
  around 
  the 
  islet 
  as 
  well 
  as 
  within 
  it 
  I 
  noted 
  

   the 
  presence 
  of 
  retia 
  mirabilia 
  upon 
  the 
  vessels 
  (fig. 
  10). 
  

   As 
  many 
  as 
  four 
  were 
  seen 
  in 
  a 
  single 
  section; 
  the 
  com- 
  

   ponent 
  vessels 
  had 
  distinct 
  walls, 
  and 
  were 
  united 
  by 
  a 
  

   surrounding 
  and 
  interlacing 
  connective 
  tissue. 
  The 
  cells 
  of 
  

   the 
  islet 
  are 
  of 
  the 
  usual 
  polyhedral 
  type, 
  with 
  cytoplasm 
  

  

  