﻿UG 
  Prof. 
  M'lntosh 
  on 
  the 
  

  

  muscular 
  anterior 
  region 
  of 
  the 
  body, 
  and 
  the 
  relaxation 
  of 
  

   its 
  retractor 
  muscles, 
  cause 
  the 
  proboscis 
  to 
  yield 
  readily 
  to 
  

   the 
  powerful 
  stream 
  of 
  blood 
  that 
  is 
  sent 
  against 
  it 
  from 
  

   behind, 
  and 
  it 
  smoothly 
  unrolls 
  outward 
  from 
  the 
  transverse 
  

   margin 
  of 
  the 
  lower 
  lip 
  like 
  a 
  very 
  supple 
  membrane, 
  the 
  

   pinkish 
  colour 
  of 
  the 
  blood 
  shining 
  through 
  the 
  translucent 
  

   tissue. 
  The 
  extrusion 
  goes 
  on 
  until 
  the 
  brownish 
  mass 
  of 
  

   the 
  pharyngeal 
  region 
  of 
  the 
  digestive 
  canal 
  approaches 
  the 
  

   front 
  of 
  the 
  first 
  body-segment, 
  and 
  sends 
  the 
  muscular 
  coil 
  

   into 
  the 
  base 
  of 
  the 
  proboscis, 
  and 
  partly 
  under 
  the 
  long 
  

   retractor 
  on 
  its 
  way 
  to 
  the 
  tip 
  — 
  like 
  a 
  plug, 
  — 
  assisting 
  to 
  

   retain 
  the 
  blood 
  therein 
  and 
  giving 
  solidity 
  to 
  the 
  whole 
  

   organ. 
  Thus, 
  in 
  its 
  progress 
  forward, 
  the 
  flattened 
  snout 
  is 
  

   thrust 
  amongst 
  the 
  sand 
  with 
  an 
  undulating 
  and 
  insinuating 
  

   motion 
  till 
  it 
  has 
  advanced 
  about 
  its 
  own 
  length 
  ; 
  then 
  the 
  

   proboscis 
  is 
  ejected 
  to 
  its 
  full 
  extent, 
  like 
  an 
  indiarubber 
  

   dilator, 
  so 
  as 
  to 
  make 
  a 
  suitable 
  channel 
  for 
  the 
  occupation 
  

   of 
  the 
  body 
  while 
  again 
  pressing 
  onward 
  the 
  exploratory 
  

   snout. 
  Then 
  all 
  the 
  retractile 
  arrangements 
  are 
  brought 
  

   into 
  play 
  — 
  the 
  fan-shaped 
  vertical 
  fibres 
  pull 
  in 
  the 
  basal 
  

   (anterior) 
  region, 
  the 
  short 
  and 
  long 
  retractors 
  act 
  on 
  the 
  

   entire 
  organ, 
  and 
  the 
  withdrawal 
  of 
  the 
  pharyngeal 
  pro- 
  

   trusion 
  makes 
  an 
  open 
  channel 
  for 
  the 
  backward 
  stream 
  of 
  

   blcod, 
  which 
  rushes 
  into 
  the 
  vessels 
  of 
  the 
  anterior 
  region 
  

   out 
  of 
  the 
  returning 
  organ, 
  further, 
  constricted 
  by 
  its 
  own 
  

   circular 
  muscular 
  coat. 
  These 
  alternate 
  protrusions 
  and 
  

   retractions 
  are 
  repeated 
  at 
  somewhat 
  regular 
  intervals, 
  and 
  

   continued 
  for 
  a 
  long 
  time. 
  Moreover, 
  an 
  explanation 
  is 
  

   perhaps 
  afforded 
  of 
  the 
  fact 
  that 
  the 
  animal 
  is 
  partial 
  to 
  fine 
  

   sand, 
  seeing 
  that 
  the 
  larger 
  sharp 
  fragments 
  of 
  coarse 
  gravel 
  

   and 
  sand 
  might 
  injure 
  either 
  snout 
  or 
  proboscis, 
  though 
  the 
  

   latter 
  is 
  specially 
  protected 
  by 
  its 
  chitinous 
  investment. 
  

  

  Puncture 
  of 
  the 
  anterior 
  region 
  of 
  the 
  body, 
  so 
  as 
  to 
  

   give 
  exit 
  to 
  the 
  blood, 
  interferes 
  with 
  the 
  extrusion 
  of 
  the 
  

   proboscis; 
  indeed, 
  it 
  is 
  not 
  generally 
  thrust 
  out 
  after 
  such 
  

   an 
  injury. 
  

  

  The 
  exsertile 
  pharyngeal 
  region 
  is 
  followed 
  by 
  a 
  mobile 
  

   part 
  of 
  the 
  alimentary 
  canal 
  that 
  undergoes 
  considerable 
  

   elongation 
  when 
  the 
  former 
  is 
  thrust 
  forward, 
  but 
  which 
  is 
  

   variously 
  coiled 
  in 
  retraction. 
  In 
  transverse 
  section 
  it 
  is 
  

   firm, 
  often 
  somewhat 
  quadrangular, 
  and 
  consists, 
  from 
  within 
  

   outward, 
  of 
  the 
  chitinous-like 
  inner 
  tunic, 
  the 
  glandular 
  

   layer 
  (of 
  less 
  depth 
  than 
  in 
  front), 
  the 
  basement-tissue, 
  and, 
  

   lastly, 
  of 
  an 
  external 
  coat 
  of 
  circular 
  muscular 
  fibres. 
  After 
  

   a 
  short 
  course 
  backward 
  the 
  calibre 
  of 
  the 
  canal 
  diminishes, 
  

   and 
  a 
  distinct 
  sheath 
  from 
  the 
  vascular 
  system 
  envelops 
  it 
  

  

  