﻿EPITHELIAL 
  ISLETS 
  OF 
  THE 
  PANCREAS 
  IN 
  TELEOSTEI. 
  383 
  

  

  Lopliius 
  piscatorius. 
  — 
  lu 
  this 
  species 
  the 
  uumber 
  of 
  

   islets 
  which 
  can 
  be 
  seen 
  in 
  a 
  naked-eye 
  examiuation 
  is 
  rehi- 
  

   tively 
  large. 
  The 
  pancreas 
  is 
  diffuse, 
  Iji^g 
  foi' 
  the 
  most 
  part 
  

   iu 
  the 
  mesenteric 
  area 
  between 
  the 
  intestine 
  anteriorly 
  and 
  

   the 
  spleen. 
  When 
  this 
  area 
  is 
  spread 
  out 
  (see 
  PI. 
  27, 
  fig. 
  2), 
  the 
  

   islets, 
  being 
  opaque, 
  may 
  be 
  easily 
  observed. 
  The 
  " 
  principal" 
  

   lies 
  a 
  short 
  distance 
  in 
  front 
  of 
  the 
  spleen, 
  several 
  others 
  are 
  

   scattered 
  between 
  the 
  cystic 
  duct 
  and 
  the 
  intestine. 
  About 
  

   half-way 
  along 
  this 
  duct, 
  between 
  it 
  and 
  the 
  intestine, 
  there 
  

   occurs 
  with 
  great 
  frequency 
  a 
  fairly 
  large 
  islet, 
  and, 
  as 
  

   already 
  noted 
  (15), 
  several 
  near 
  the 
  pylorus, 
  amongst 
  which 
  

   is 
  the 
  second 
  largest 
  in 
  size 
  in 
  this 
  species. 
  In 
  appearance 
  

   they 
  are 
  most 
  frequently 
  quite 
  white, 
  sometimes 
  the 
  minute 
  

   vessels 
  on 
  their 
  surface 
  show 
  as 
  fine 
  red 
  streaks, 
  and 
  at 
  

   others 
  they 
  are 
  so 
  distended 
  with 
  blood 
  as 
  to 
  give 
  the 
  organ 
  a 
  

   dark 
  ruddy 
  hue. 
  This 
  variable 
  appearance 
  doubtless 
  has 
  

   some 
  relation 
  to 
  the 
  fact 
  that 
  retia 
  mirabilia 
  are 
  numerous 
  

   in 
  and 
  around 
  the 
  organ. 
  The 
  principal 
  islet 
  is 
  in 
  large 
  

   specimens 
  frequently 
  of 
  relatively 
  great 
  size. 
  It 
  is 
  flattened, 
  

   circular 
  as 
  a 
  rule 
  iu 
  outline, 
  and 
  ellipsoid 
  in 
  vertical 
  section. 
  

   In 
  one 
  case 
  it 
  measured 
  14 
  mm. 
  iu 
  diameter, 
  and 
  about 
  5 
  mm. 
  

   across 
  its 
  thickest 
  part. 
  It 
  not 
  infrequently 
  in 
  adults 
  is 
  as 
  

   large 
  as 
  the 
  supra-renal 
  of 
  a 
  rabbit. 
  The 
  islet 
  near 
  the 
  

   pylorus 
  I 
  have 
  found 
  8 
  mm. 
  in 
  diameter. 
  They 
  are 
  sur- 
  

   rounded 
  by 
  a 
  loose 
  capsule 
  of 
  areolar 
  tissue. 
  

  

  Cottus 
  scorpius. 
  — 
  The 
  pancreas 
  in 
  this 
  species 
  is 
  in 
  the 
  

   form 
  of 
  narrow 
  bands 
  adhering 
  to 
  the 
  intestine, 
  and 
  

   occupying 
  the 
  intercsecal 
  spaces. 
  One 
  of 
  these 
  bands 
  lies 
  

   near 
  the 
  spleen. 
  Immediately 
  above 
  this 
  organ 
  the 
  principal 
  

   islet 
  may 
  be 
  seen 
  with 
  great 
  distinctness 
  even 
  in 
  small 
  

   specimens 
  as 
  a 
  pale, 
  somewhat 
  angular 
  mass 
  faintly 
  streaked 
  

   with 
  blood-vessels. 
  The 
  portal 
  vein 
  passes 
  close 
  to 
  it, 
  and 
  

   the 
  main 
  branches 
  of 
  the 
  coeliaco-mesenteric 
  artery 
  pass 
  

   ventralwards 
  a 
  little 
  distance 
  in 
  front. 
  In 
  a 
  specimen 
  22 
  cm. 
  

   long 
  the 
  islet 
  measured 
  3 
  mm. 
  in 
  diameter. 
  

  

  Cyclopterus 
  lump 
  us. 
  — 
  Here 
  there 
  is 
  a 
  principal 
  islet 
  

   situated 
  slightly 
  anterior 
  to 
  the 
  spleen. 
  Its 
  position 
  and 
  

  

  VOL. 
  48, 
  PART 
  3. 
  NEW 
  SERIES. 
  28 
  

  

  