﻿398 
  JOHN 
  RENNIE. 
  

  

  instances, 
  however, 
  they 
  could 
  be 
  seen 
  in 
  serial 
  sections 
  to 
  

   be 
  continuous 
  with 
  the 
  same 
  tissue 
  outside 
  (figs. 
  5 
  and 
  8). 
  I 
  

   do 
  not 
  consider 
  it 
  a 
  feature 
  of 
  any 
  morphological 
  importance. 
  

   In 
  all 
  the 
  cases 
  where 
  the 
  peculiarity 
  was 
  noted 
  the 
  pancreas 
  

   is 
  of 
  a 
  very 
  diffuse 
  type, 
  and 
  in 
  the 
  spreading 
  of 
  its 
  alveoli 
  

   during 
  development, 
  as 
  is 
  well 
  known, 
  it 
  may 
  invade 
  or 
  

   become 
  attached 
  to 
  other 
  organs 
  of 
  independent 
  function. 
  A 
  

   common 
  feature 
  is 
  the 
  close 
  envelopment 
  of 
  the 
  leading 
  blood- 
  

   vessels 
  throughout 
  the 
  body-cavity 
  by 
  long 
  strands 
  of 
  pan- 
  

   creatic 
  tissue, 
  and 
  in 
  several 
  instances 
  (Syngathus, 
  Pleuro- 
  

   nectes) 
  such 
  tissue 
  accompanies 
  the 
  vessels 
  within 
  the 
  liver, 
  

   ramifying 
  with 
  these 
  throughout 
  the 
  tissue 
  of 
  that 
  organ. 
  

  

  Pancreatic 
  elements 
  penetrating 
  the 
  islets 
  are 
  supported 
  by 
  

   connective 
  tissue, 
  which 
  is 
  continuous 
  with 
  such 
  tissue 
  beyond 
  

   and 
  around 
  the 
  islet. 
  On 
  account 
  of 
  this 
  Diamare 
  has 
  argued 
  

   that 
  the 
  capsule 
  is 
  of 
  the 
  nature 
  of 
  interstitial 
  tissue 
  of 
  the 
  

   pancreas, 
  and 
  that 
  here, 
  owing 
  to 
  the 
  larger 
  development 
  of 
  

   these 
  islets, 
  it 
  has 
  assumed 
  a 
  capsular 
  form 
  ; 
  and 
  he 
  definitely 
  

   opposes 
  the 
  interpretation 
  that 
  the 
  tissue 
  enclosed 
  by 
  the 
  

   capsule 
  is 
  merely 
  joined 
  to 
  the 
  pancreas, 
  and 
  is 
  not 
  an 
  inherent 
  

   portion 
  of 
  it. 
  The 
  capsule, 
  he 
  says, 
  in 
  these 
  cases 
  is 
  a 
  

   " 
  secondary 
  " 
  formation. 
  

  

  The 
  view 
  thus 
  contested 
  is, 
  from 
  evidence 
  ah'eady 
  partly 
  

   submitted 
  and 
  partly 
  to 
  follow, 
  one 
  that 
  I 
  continue 
  to 
  hold. 
  

   In 
  the 
  first 
  instance 
  we 
  may 
  recall 
  the 
  fact 
  just 
  referred 
  to 
  

   that 
  a 
  pancreas, 
  intra-hepatic, 
  exists 
  ; 
  and 
  if 
  it 
  can 
  invade 
  the 
  

   tissue 
  of 
  an 
  organ 
  undoubtedly 
  distinct 
  and 
  having 
  embry- 
  

   onically 
  a 
  separate 
  origin, 
  there 
  is 
  no 
  argument 
  for 
  identity 
  

   in 
  the 
  fact 
  that 
  pancreas 
  is 
  found 
  sometimes 
  within 
  another 
  

   organ 
  which 
  has 
  its 
  rise 
  from 
  the 
  same 
  embryonic 
  tissue,^ 
  and 
  

   which 
  we 
  may 
  assume 
  is 
  from 
  the 
  first 
  in 
  closer 
  proximity. 
  

   Further, 
  I 
  find 
  the 
  capsule 
  is 
  best 
  developed 
  where, 
  owing 
  to 
  

  

  ' 
  According 
  to 
  Laguesse 
  (9) 
  and, 
  more 
  recently, 
  Pearce 
  (14), 
  they 
  Lave 
  the 
  

   same 
  embryonic 
  origin. 
  'I'his 
  does 
  not 
  affect 
  the 
  present 
  argument, 
  for 
  we 
  

   recall 
  such 
  facts 
  as 
  the 
  origin 
  of 
  thymus 
  and 
  thyroid 
  from 
  branchial 
  epithelium, 
  

   and 
  (according 
  to 
  S. 
  Vincent) 
  the 
  medulla 
  of 
  the 
  supra-renal 
  from 
  sympathetic 
  

   elements. 
  — 
  J. 
  11. 
  

  

  