﻿382 
  JOHN 
  RENNir-l. 
  

  

  L 
  o 
  p 
  h 
  o 
  b 
  r 
  a 
  11 
  c 
  h 
  i 
  i 
  : 
  

  

  Syngiiatlius 
  acns, 
  Neropliis 
  sequorcus, 
  

   Siphonostoiiia 
  typlile. 
  

  

  General 
  Relations 
  of 
  the 
  Islets. 
  

  

  The 
  following 
  account 
  indicates 
  the 
  general 
  relations 
  and 
  

   macroscopic 
  appearance 
  of 
  the 
  bodies 
  observed. 
  In 
  most 
  

   instances, 
  particularly 
  in 
  those 
  cases 
  where 
  a 
  " 
  principal 
  

   islet" 
  is 
  stated 
  to 
  exist, 
  numerous 
  specimens 
  were 
  examined. 
  

  

  Cyprinus 
  carpio. 
  — 
  The 
  islets 
  observed 
  in 
  this 
  species 
  

   are 
  among 
  the 
  smallest 
  found. 
  The 
  pancreas 
  is 
  diffuse, 
  and 
  

   they 
  appear 
  in 
  sections 
  of 
  it 
  in 
  different 
  regions 
  of 
  the 
  body- 
  

   cavity. 
  In 
  some 
  instances 
  they 
  lie 
  alongside 
  the 
  zymogenous 
  

   tissue, 
  but 
  in 
  most 
  instances 
  they 
  are 
  surrounded 
  by 
  it, 
  and 
  do 
  

   not 
  possess 
  a 
  limiting 
  capsule. 
  

  

  Zeus 
  faber. 
  — 
  Here 
  there 
  exists 
  a 
  " 
  principal 
  islet/' 
  which, 
  

   in 
  specimens 
  of 
  about 
  25 
  cm., 
  is 
  as 
  large 
  as 
  5 
  mm. 
  in 
  length. 
  

   There 
  are 
  also 
  smaller 
  forms 
  in 
  the 
  neighbourhood 
  of 
  the 
  

   pyloric 
  cseca 
  which 
  may 
  be 
  dissected 
  out, 
  and 
  also 
  numerous 
  

   microscopic 
  ones 
  within 
  the 
  intercaecal 
  pancreatic 
  masses. 
  

   The 
  principal 
  islet 
  lies 
  within 
  a 
  small 
  mass 
  of 
  zymogenous 
  

   tissue, 
  which 
  is 
  attached 
  to 
  the 
  base 
  of 
  the 
  gall-bladder 
  (see 
  

   PI. 
  26, 
  fig. 
  1). 
  It 
  and 
  the 
  smaller 
  ones 
  near 
  the 
  cteca 
  were 
  found 
  

   ovoid 
  in 
  form. 
  The 
  intercEecal 
  examples 
  which 
  are 
  invested 
  

   by 
  more 
  compact 
  masses 
  of 
  zymogenous 
  tissue, 
  are 
  rounded, 
  

   oval, 
  or 
  irregular 
  in 
  outline. 
  In 
  serial 
  sections 
  they 
  are 
  seen 
  

   to 
  vary 
  a 
  good 
  deal 
  in 
  this 
  respect, 
  owing 
  to 
  their 
  being 
  

   closely 
  surrounded 
  by 
  the 
  irregularly 
  arranged 
  pancreatic 
  

   alveoli. 
  The 
  large 
  forms 
  have 
  a 
  more 
  or 
  less 
  distinct 
  limiting 
  

   capsule 
  ; 
  such 
  a 
  structure 
  is 
  not 
  present 
  in 
  the 
  smaller 
  ones 
  

   within 
  the 
  compact 
  masses 
  of 
  the 
  pancreas. 
  

  

  Agonus 
  cataphractus. 
  — 
  In 
  this 
  species, 
  occupying 
  a 
  

   position 
  between 
  the 
  gall-bladder 
  and 
  the 
  spleen, 
  within 
  a 
  

   small 
  mass 
  of 
  pancreatic 
  tissue, 
  is 
  the 
  principal 
  islet. 
  A 
  

   similar 
  body 
  occurs 
  close 
  to 
  the 
  pyloric 
  caeca. 
  Both 
  are 
  

   contained 
  within 
  a 
  firm 
  connective-tissue 
  capsule. 
  

  

  