﻿STRUCTURE 
  OF 
  THE 
  DIGESTIVE 
  CANAL. 
  209 
  

  

  are 
  not 
  quite 
  sufficient. 
  The 
  descriptions, 
  both 
  general 
  and 
  histological, 
  

   refer 
  to 
  the 
  locusts 
  unless 
  expressly 
  stated 
  to 
  refer 
  to 
  the 
  cricket. 
  

  

  The 
  best 
  method 
  with 
  which 
  I 
  am 
  acquainted 
  for 
  readily 
  obtaining 
  

   a 
  general 
  view 
  of 
  the 
  course 
  and 
  divisions 
  of 
  the 
  digestive 
  tract 
  is 
  the 
  

   following 
  : 
  Place 
  a 
  female 
  (a 
  male 
  will 
  do, 
  but 
  is 
  not 
  quite 
  so 
  good) 
  in 
  

   alcohol 
  of 
  about 
  50 
  to 
  60 
  per 
  cent, 
  for 
  from 
  12 
  to 
  24 
  hours; 
  then 
  

   put 
  it 
  in 
  strong 
  alcohol 
  (96 
  per 
  cent.) 
  for 
  a 
  day 
  or 
  longer; 
  then, 
  with 
  a 
  

   sharp 
  razor, 
  cut 
  it 
  carefully 
  into 
  halves 
  along 
  the 
  median 
  line, 
  so 
  as 
  to 
  

   have 
  the 
  right 
  and 
  left 
  sides 
  separately. 
  Lay 
  the 
  pieces 
  under 
  alcohol, 
  

   and 
  carefully 
  remove 
  the 
  contents 
  of 
  the 
  digestive 
  canal, 
  which 
  will 
  

   then 
  appear 
  very 
  plainly, 
  its 
  course, 
  being 
  as 
  represented 
  in 
  Fig. 
  45. 
  

   The 
  cavity 
  of 
  the 
  mouth, 
  Jf, 
  ascends 
  obliquely 
  forward, 
  and 
  is 
  generally 
  

   found 
  filled 
  with 
  a 
  black 
  mass, 
  the 
  coagulated 
  " 
  molasses 
  n 
  which 
  grass- 
  

   hoppers 
  pour 
  out 
  when 
  caught 
  or 
  irritated. 
  The 
  oesophagus, 
  00., 
  is 
  nar- 
  

   rower, 
  of 
  uniform 
  diameter, 
  it 
  curves 
  upwards 
  and 
  backwards, 
  terminat- 
  

   ing 
  very 
  nearly 
  in 
  the 
  center 
  of 
  the 
  head, 
  where 
  it 
  opens 
  into 
  the 
  very 
  

   large 
  crop, 
  Or. 
  The 
  crop 
  extends 
  through 
  the 
  posterior 
  half 
  of 
  the 
  

   head 
  and 
  the 
  whole 
  of 
  the 
  thorax 
  ; 
  it 
  attains 
  its 
  greatest 
  diameter 
  in 
  

   the 
  prothorax, 
  behind 
  which 
  it 
  descends, 
  tapering 
  off 
  slightly, 
  and 
  end- 
  

   ing 
  in 
  the 
  proventiculus, 
  P. 
  The 
  crop 
  itself 
  is 
  divisible 
  into 
  two 
  dis- 
  

   tinct 
  portions 
  : 
  1, 
  the 
  anterior 
  (O. 
  1 
  ) 
  lies 
  in 
  the 
  head 
  and 
  prothorax, 
  and 
  

   is 
  characterized 
  by 
  the 
  somewhat 
  irregular 
  transverse 
  ridges 
  on 
  its 
  

   inner 
  surface 
  ; 
  in 
  Galoptenus 
  spretus, 
  the 
  Eocky 
  Mountain 
  locust, 
  these 
  

   ridges 
  are 
  somewhat 
  less 
  numerous 
  and 
  powerful 
  than 
  in 
  0. 
  femur- 
  

   rubrum; 
  2, 
  the 
  posterior 
  (Or. 
  2 
  ), 
  in 
  which 
  the 
  ridges 
  are 
  longitudinal 
  and 
  

   much 
  smaller 
  and 
  closer 
  together 
  than 
  in 
  the 
  front 
  segment 
  ; 
  the 
  shape 
  

   of 
  the 
  posterior 
  division 
  is 
  that 
  of 
  a 
  truncated 
  cone. 
  The 
  proventriculus 
  

   (Kaumageri) 
  P, 
  is 
  so 
  much 
  reduced 
  in 
  the 
  grasshopper 
  that 
  it 
  appears 
  

   as 
  hardly 
  more 
  than 
  the 
  terminal 
  portion 
  of 
  the 
  crop, 
  instead 
  of 
  being 
  

   a 
  large 
  and 
  distinct 
  segment 
  of 
  the 
  digestive 
  canal 
  as 
  in 
  other 
  Or- 
  

   thoptera. 
  The 
  Kaumagen 
  opens 
  into 
  the 
  large 
  " 
  chylific 
  stomach 
  " 
  or 
  

   ventricle, 
  ven., 
  which 
  extends 
  along 
  the 
  ventral 
  surface 
  about 
  half 
  the 
  

   length 
  of 
  the 
  abdomen. 
  At 
  its 
  anterior 
  end 
  it 
  gives 
  off 
  the 
  six 
  blind 
  

   pouches, 
  so 
  long 
  known 
  and 
  so 
  frequently 
  described 
  ; 
  in 
  a 
  longitudinal 
  

   section 
  only 
  one 
  of 
  these 
  can 
  be 
  seen 
  (Div.) 
  extending 
  forwards 
  under- 
  

   neath 
  the 
  crop. 
  The 
  first 
  part 
  of 
  the 
  intestine 
  I 
  propose 
  to 
  call 
  the 
  

   Ileum, 
  II. 
  It 
  appears 
  at 
  first 
  sight 
  as 
  the 
  direct 
  continuation, 
  or 
  rather 
  

   as 
  the 
  posterior 
  division, 
  of 
  the 
  stomach, 
  from 
  which, 
  however, 
  it 
  is 
  in 
  

   reality 
  perfectly 
  distinct, 
  both 
  by 
  its 
  structure 
  and 
  by 
  its 
  separation 
  

   through 
  a 
  peculiar 
  valve, 
  which 
  I 
  shall 
  describe 
  later. 
  The 
  Malpighian 
  

   vessels 
  open 
  just 
  underneath 
  and 
  in 
  front 
  of 
  this 
  valve. 
  The 
  second 
  

   division 
  of 
  the 
  intestine 
  I 
  call 
  the 
  colon, 
  col., 
  a 
  name 
  sometimes 
  applied 
  

   by 
  older 
  authors 
  to 
  the 
  rectum. 
  The 
  colon 
  is 
  smaller 
  in 
  diameter 
  than 
  

   any 
  other 
  part 
  of 
  the 
  digestive 
  tube 
  ; 
  it 
  ascends 
  and 
  opens 
  into 
  the 
  

   rectum, 
  R. 
  The 
  rectum 
  extends 
  horizontally 
  directly 
  underneath 
  the 
  

   dorsum 
  ; 
  its 
  diameter 
  is 
  about 
  two-thirds 
  that 
  of 
  the 
  stomach 
  ; 
  its 
  inner 
  

   14 
  L 
  

  

  