﻿THE 
  BRAIN 
  OF 
  THE 
  LOCUST. 
  235 
  

  

  The 
  antennal 
  or 
  olfactory 
  lobes. 
  — 
  Section 
  19. 
  (PI. 
  XI, 
  Fig. 
  L, 
  ant. 
  I.) 
  

   These 
  are 
  smaller 
  than 
  the 
  optic 
  lobes, 
  though 
  in 
  section 
  19 
  they 
  ap- 
  

   pear 
  larger. 
  They 
  give 
  rise 
  to 
  the 
  antennal 
  nerve, 
  and 
  as 
  the 
  locust 
  

   carries 
  its 
  ears 
  at 
  the 
  base 
  of 
  the 
  abdomen, 
  the 
  auditory 
  nerves 
  entering 
  

   the 
  third 
  thoracic 
  ganglion, 
  reasoning 
  by 
  exclusion 
  the 
  antenna? 
  in 
  

   Orthoptera 
  must 
  be 
  organs 
  of 
  smell, 
  and 
  the 
  lobes 
  and 
  nerves 
  to 
  the 
  an- 
  

   tenna 
  1 
  are 
  consequently 
  olfactory. 
  This 
  is 
  the 
  opinion 
  of 
  some 
  recent 
  

   writers, 
  notably 
  Hanser. 
  389 
  The 
  lobes 
  are, 
  as 
  described 
  by 
  the 
  other 
  

   observers, 
  filled 
  with 
  ball-like 
  yellowish 
  masses, 
  which 
  stain 
  dark 
  by 
  osmic 
  

   acid, 
  much 
  as 
  in 
  the 
  commissural 
  lobes. 
  Xerve 
  fibers 
  are 
  seen 
  in 
  sec- 
  

   tion 
  19 
  to 
  pass 
  from 
  one 
  antennal 
  lobe 
  to 
  the 
  other 
  in 
  the 
  rear 
  of 
  the 
  cen- 
  

   tral 
  body 
  and 
  of 
  the 
  trabecular, 
  while 
  other 
  nerve 
  fibers 
  are 
  seen 
  to 
  pass 
  

   into 
  the 
  optic 
  lobes 
  and 
  the 
  commissural 
  lobes. 
  This 
  system 
  of 
  intra- 
  

   lobal 
  nerves 
  demonstrates 
  that 
  there 
  is 
  a 
  nervous 
  intercommunication 
  

   between 
  these 
  cerebral 
  lobes 
  and 
  the 
  ganglionic 
  chain 
  of 
  the 
  entire 
  body. 
  

  

  The 
  commissural 
  lobes. 
  — 
  From 
  these 
  large 
  bodies 
  proceed 
  the 
  two 
  great 
  

   longitudinal 
  commissural 
  nerves, 
  forming 
  the 
  connecting 
  threads 
  of 
  the 
  

   nervous 
  cord, 
  and 
  which 
  extend 
  from 
  the 
  brain 
  to 
  the 
  last 
  abdominal 
  

   ganglion, 
  passing 
  through 
  the 
  intermediate 
  nerve 
  centers. 
  The 
  lobes 
  

   are 
  filled 
  with 
  ball-like 
  masses, 
  of 
  the 
  same 
  general 
  appearance 
  as 
  in 
  the 
  

   antennal 
  lobes, 
  but 
  more 
  distinct 
  and 
  numerous. 
  

  

  Comparison 
  of 
  the 
  brain 
  of 
  the 
  locust 
  icith 
  that 
  of 
  other 
  insects. 
  — 
  Xewton 
  

   rightly 
  regards 
  the 
  cockroach's 
  brain 
  as 
  a 
  generalized 
  form 
  of 
  brain, 
  

   which 
  may 
  serve 
  as 
  a 
  standard 
  of 
  comparison. 
  The 
  cockroach 
  is 
  geologi- 
  

   cally 
  one 
  of 
  the 
  oldest 
  of 
  insects 
  ; 
  its 
  external 
  and 
  internal 
  structure 
  is 
  

   on 
  a 
  generalized 
  plan, 
  and 
  the 
  brain 
  conforms 
  to 
  this 
  order 
  of 
  things. 
  

   Our 
  knowledge 
  of 
  the 
  cockroach's 
  brain 
  is 
  derived 
  from 
  the 
  photographs 
  

   and 
  account 
  of 
  Flogel, 
  and 
  Xewton's 
  excellent 
  descriptions 
  and 
  figures, 
  

   supplemented 
  by 
  two 
  sets 
  of 
  sections 
  made 
  for 
  us 
  by 
  Mr. 
  Mason, 
  but 
  

   which, 
  unfortunately, 
  are 
  quite 
  defective 
  as 
  regards 
  the 
  trabecular 
  and 
  

   stalk 
  of 
  the' 
  mushroom 
  body. 
  The 
  shape 
  of 
  the 
  calices 
  of 
  the 
  cockroach, 
  

   as 
  already 
  stated, 
  is 
  very 
  different 
  from 
  that 
  of 
  these 
  bodies 
  in 
  the 
  locust, 
  

   and 
  indeed 
  from 
  any 
  other 
  insect, 
  the 
  cup 
  being 
  very 
  deep 
  and 
  the 
  sides 
  

   thin 
  ; 
  but 
  the 
  intimate 
  structure 
  seems 
  nearly 
  the 
  same 
  in 
  the 
  two 
  insects. 
  

  

  In 
  the 
  cockroach 
  the 
  antennal 
  and 
  commissural 
  lobes 
  are 
  of 
  much 
  

   looser 
  texture, 
  with 
  large 
  and 
  numerous 
  ball-like 
  masses 
  (ballensubstanz) 
  : 
  

   these 
  are, 
  when 
  magnified 
  100 
  diameters, 
  not 
  only 
  larger, 
  but 
  more 
  dis- 
  

   tinct 
  from 
  the 
  rest 
  of 
  the 
  nervous 
  matter 
  of 
  the 
  lobe 
  than 
  in 
  the 
  locust. 
  

   When 
  magnified 
  as 
  mentioned, 
  the 
  ball-like 
  masses 
  appear 
  to 
  be 
  simple 
  

   masses 
  of 
  finely 
  granular 
  nervous 
  matter, 
  with 
  darker 
  granules, 
  much 
  

   like 
  the 
  rest 
  of 
  the 
  granular 
  portions 
  of 
  the 
  brain, 
  but 
  with 
  coarser 
  

   granular 
  masses 
  than 
  in 
  the 
  substance 
  of 
  the 
  optic 
  lobes. 
  These 
  ball- 
  

   like 
  masses 
  are 
  surrounded 
  by 
  a 
  loose 
  net-work 
  of 
  anastomosing 
  nerve 
  

   fibers 
  continuous 
  with 
  those 
  of 
  the 
  antennal 
  nerve, 
  and 
  with 
  scattered 
  

  

  s^Physiologische 
  nnd 
  histiologische 
  Untersuchungen 
  iiber 
  das 
  Geruchsorgan 
  der 
  Insekten. 
  Siet>ol<J 
  

   mid 
  Kolliker's 
  Zeitschrift 
  ftir 
  Wissen. 
  Zoologie, 
  Bd. 
  34, 
  Heft. 
  3. 
  

  

  