﻿443 
  Prof. 
  M'Intosh 
  on 
  the 
  

  

  in 
  front 
  of 
  the 
  intestine. 
  In 
  Magelona 
  the 
  buccal 
  and 
  

   pharyngeal 
  regions 
  receive 
  the 
  food, 
  the 
  great 
  development 
  

   of 
  the 
  muscular 
  and 
  glandular 
  tunics 
  in 
  the 
  latter 
  specially 
  

   pointing 
  it 
  out 
  as 
  an 
  important 
  part 
  of 
  the 
  canal. 
  The 
  

   smoother 
  portion 
  behind 
  probably 
  acts 
  both 
  as 
  an 
  oesophageal 
  

   and 
  a 
  ventricular 
  chamber, 
  and 
  thus 
  the 
  food 
  would 
  be 
  partly 
  

   digested 
  before 
  passing 
  the 
  barrier 
  at 
  the 
  ninth 
  body- 
  

   segment. 
  

  

  Intestinal 
  Region 
  Proper. 
  

  

  The 
  anterior 
  border 
  of 
  the 
  tenth 
  body-segment 
  shows 
  in 
  

   transverse 
  section 
  the 
  whole 
  tube 
  greatly 
  enlarged, 
  while 
  

   its 
  glandular 
  lining 
  is 
  in 
  a 
  transition-stage 
  dorsally 
  and 
  

   ventrally. 
  In 
  the 
  latter 
  regions 
  the 
  tissue 
  is 
  composed 
  of 
  

   closely 
  arranged 
  — 
  almost 
  linear 
  — 
  granular 
  glands. 
  Then 
  the 
  

   entire 
  canal 
  assumes 
  the 
  soft 
  greenish 
  glandular 
  condition 
  

   characteristic 
  of 
  the 
  posterior 
  division, 
  its 
  superior 
  arch 
  being 
  

   surmounted 
  by 
  and 
  incorporated 
  with 
  the 
  investment 
  of 
  the 
  

   two 
  great 
  dorsal 
  blood-vessels. 
  Viewed 
  from 
  the 
  dorsum 
  

   in 
  the 
  living 
  animal 
  at 
  the 
  anterior 
  third 
  of 
  the 
  region, 
  the 
  

   centre 
  is 
  occupied 
  by 
  the 
  dorsal 
  vessels 
  and 
  the 
  compressed 
  

   glands, 
  each 
  with 
  its 
  central 
  oil-globules 
  ; 
  and 
  occasionally 
  

   a 
  peculiar 
  ramose 
  or 
  radiated 
  appearance 
  is 
  assumed 
  by 
  the 
  

   contents 
  spreading 
  from 
  the 
  latter 
  as 
  a 
  centre. 
  At 
  the 
  sides 
  

   are 
  large 
  masses 
  of 
  bright 
  orange 
  oil-globules 
  enclosed 
  in 
  a 
  

   limiting 
  membrane, 
  and 
  the 
  presence 
  of 
  these 
  usually 
  gives 
  

   the 
  canal 
  a 
  deep 
  brownish-orange 
  colour 
  by 
  transmitted 
  

   light. 
  Moreover, 
  if 
  the 
  specimen 
  is 
  in 
  good 
  condition 
  the 
  

   blood-vessels 
  of 
  the 
  alimentary 
  wall 
  are 
  seen 
  as 
  little 
  beads 
  

   as 
  they 
  bend 
  over 
  the 
  margin, 
  under 
  pressure. 
  In 
  a 
  lateral 
  

   view 
  the 
  prominent 
  condition 
  of 
  the 
  masses 
  containing 
  the 
  

   oil-globules 
  is 
  still 
  more 
  apparent. 
  When 
  the 
  gland-cells 
  

   are 
  extruded 
  into 
  sea-water 
  they 
  appear 
  as 
  circular 
  bodies 
  

   rilled 
  with 
  minute 
  granules, 
  and 
  generally 
  presenting 
  a 
  pale 
  

   greenish 
  hue. 
  As 
  a 
  rule 
  the 
  glandular 
  mucous 
  tissue 
  forms 
  

   a 
  thinner 
  layer 
  of 
  lobate 
  masses 
  (in 
  section) 
  along 
  the 
  dorsal 
  

   arch, 
  and 
  a 
  thicker 
  and 
  more 
  lax 
  coating 
  of 
  large 
  glands 
  

   laterally 
  ; 
  but, 
  of 
  course, 
  much 
  depends 
  on 
  the 
  degree 
  of 
  

   contraction 
  and 
  the 
  quantity 
  of 
  alimentary 
  matter. 
  In 
  

   longitudinal 
  sections 
  of 
  the 
  canal 
  the 
  soft 
  glandular 
  lining 
  

   is 
  thrown 
  at 
  somewhat 
  regular 
  intervals 
  into 
  very 
  sym- 
  

   metrical 
  dendritic 
  masses. 
  Circular 
  fibres 
  occur 
  all 
  the 
  way 
  

   backward, 
  though 
  they 
  are 
  so 
  thin 
  as 
  hardly 
  to 
  merit 
  the 
  

   name 
  of 
  a 
  special 
  tunic, 
  and 
  their 
  feebleness 
  is 
  shown 
  by 
  

   the 
  marked 
  constrictions 
  at 
  the 
  dissepiments, 
  which 
  cause 
  

   the 
  canal 
  to 
  assume 
  a 
  moniliform 
  appearance 
  — 
  well 
  seen 
  in 
  

  

  