﻿THE 
  DIGESTIVE 
  CANAL 
  AS 
  A 
  WHOLE. 
  221 
  

  

  six 
  diverticula 
  arising 
  from 
  the 
  stomach, 
  and 
  twelve 
  longitudinal 
  folds 
  

   in 
  each 
  diverticulum. 
  There 
  are 
  twelve 
  (twice 
  six) 
  gastroileal 
  folds, 
  ar- 
  

   ranged 
  in 
  twos, 
  each 
  pair 
  appearing 
  as 
  the 
  double 
  anterior 
  termination 
  

   of 
  one 
  of 
  the 
  six 
  ileal 
  folds, 
  which, 
  changing 
  their 
  character, 
  extend 
  

   backwards 
  through 
  the 
  colon 
  ; 
  finally, 
  in 
  the 
  rectum 
  there 
  are 
  six 
  rectal 
  

   glands. 
  

  

  The 
  three 
  divisions 
  of 
  the 
  digestive 
  canal 
  are 
  perfectly 
  natural; 
  their 
  

   existence 
  of 
  itself 
  suggests 
  that 
  they 
  represent 
  the 
  three 
  segments 
  which 
  

   are 
  usually 
  distinguished 
  upon 
  embryological 
  grounds, 
  namely, 
  the 
  fore- 
  

   gut, 
  midgut, 
  hindgut 
  (Vorderdarm, 
  Mitteldarm, 
  and 
  Hinterdarm). 
  This 
  

   supposition 
  is 
  strengthened 
  by 
  Bobretzky's 
  319 
  observation 
  that 
  in 
  dec- 
  

   apods 
  the 
  embryological 
  foregut 
  forms 
  the 
  oesophagus 
  and 
  Kaumagen, 
  

   while 
  the 
  midgut 
  forms 
  the 
  follicular 
  stomach 
  and 
  diverticula 
  (liver). 
  

   This 
  is 
  a 
  strong 
  confirmation 
  of 
  the 
  conclusion 
  that 
  I 
  have 
  been 
  induced 
  

   to 
  consider 
  probable 
  upon 
  purely 
  anatomical 
  grounds. 
  It 
  seems 
  to 
  me, 
  

   moreover, 
  that 
  Hatsckek's 
  320 
  observations 
  also 
  point 
  to 
  the 
  same 
  conclu- 
  

   sion, 
  viz, 
  that 
  the 
  ventriculus 
  (Chylusmagen), 
  together 
  with 
  its 
  append- 
  

   ages, 
  represents 
  the 
  midgut, 
  all 
  in 
  front 
  being 
  foregut, 
  and 
  all 
  posterior 
  

   to 
  it 
  arising 
  from 
  the 
  hindgut. 
  

  

  The 
  principal 
  respects 
  in 
  which 
  the 
  middle 
  division 
  differs 
  from 
  the 
  

   other 
  two 
  is 
  by, 
  1, 
  its 
  glandular 
  character; 
  2, 
  the 
  presence 
  of 
  a 
  delicate 
  

   cuticula, 
  probably 
  not 
  chitinous; 
  and, 
  3, 
  of 
  unstriated 
  muscles. 
  It 
  seems 
  

   to 
  me 
  now 
  a 
  legitimate 
  problem 
  in 
  insect 
  anatomy 
  to 
  determine 
  whether 
  

   these 
  characteristics 
  are 
  applicable 
  to 
  the 
  midgut 
  of 
  all 
  insects. 
  

  

  In 
  all 
  parts 
  of 
  the 
  digestive 
  tract 
  the 
  succession 
  of 
  the 
  layers 
  is 
  the 
  

   same: 
  1st, 
  a 
  cuticula; 
  2d, 
  an 
  epithelium; 
  3d, 
  connective 
  tissue; 
  4th, 
  

   muscles. 
  Besides 
  which 
  there 
  is 
  stated 
  to 
  be 
  a 
  pavement 
  epithelium 
  

   (serosa) 
  outside 
  the 
  muscles 
  in 
  some 
  insects. 
  This 
  I 
  have 
  not 
  observed 
  

   in 
  the 
  grasshoppers, 
  though 
  it 
  may 
  be 
  present. 
  

  

  Of 
  the 
  physiological 
  functions 
  of 
  the 
  single 
  parts 
  of 
  the 
  digestive 
  

   canal 
  little 
  is 
  really 
  known, 
  though 
  some 
  observations 
  have 
  been 
  pub- 
  

   lished 
  by 
  Sirodot 
  and 
  Plateaux. 
  

  

  I 
  should 
  like 
  to 
  interpolate 
  here 
  a 
  comparison, 
  which 
  is 
  curious 
  and 
  

   odd 
  rather 
  than 
  of 
  scientific 
  value. 
  After 
  Malpighi 
  had 
  shown 
  that 
  the 
  

   grasshopper 
  had 
  several 
  stomachs, 
  some 
  of 
  the 
  older 
  authors, 
  according 
  

   to 
  Colin, 
  considered 
  these 
  insects 
  to 
  be 
  ruminants, 
  comparing 
  the 
  vari- 
  

   ous 
  parts 
  of 
  their 
  digestive 
  canal 
  with 
  the 
  divisions 
  of 
  the 
  stomach 
  in 
  

   the 
  true 
  ruminants. 
  Of 
  course 
  this 
  idea 
  is 
  now 
  entirely 
  rejected, 
  but 
  it 
  

   is 
  nevertheless 
  curious 
  to 
  notice 
  that 
  with 
  our 
  present 
  knowledge 
  we 
  

   can 
  trace 
  an 
  analogy 
  between 
  the 
  crop 
  and 
  the 
  rumen, 
  the 
  ventricle 
  of 
  

   the 
  grasshopper 
  and 
  the 
  sheep, 
  while 
  the 
  diverticula 
  with 
  their 
  leaf 
  -like 
  

   folds 
  singularly 
  imitate 
  the 
  structure 
  of 
  the 
  psalter. 
  Those 
  who 
  are 
  not 
  

   familiar 
  with 
  the 
  anatomy 
  of 
  ruminants, 
  will 
  find 
  a 
  clear 
  and 
  excellent 
  

   account 
  in 
  Huxley's 
  Anatomy 
  of 
  Yertebrated 
  Animals. 
  

  

  319 
  Bobretzky 
  : 
  Zux 
  Embryologie 
  der 
  Arthropoden 
  (in 
  Russian) 
  as 
  abstracted 
  by 
  Hoyer 
  in 
  Hoffmann 
  und 
  

   Schwalbe. 
  Jahresbericht 
  der 
  Physiol, 
  n. 
  Anat. 
  fur 
  1873, 
  p. 
  314. 
  

  

  3*> 
  B. 
  Hatschek: 
  Beitrage 
  zur 
  Entro. 
  Lepidopteren. 
  Jena 
  Zeitschr. 
  Bd. 
  XL 
  (1877), 
  (p. 
  17 
  des 
  Separatab- 
  

   druckes.) 
  

  

  