﻿228 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  and 
  ocellar 
  nerves 
  and 
  posterior 
  commissures 
  originate 
  from 
  the- 
  large 
  

   ganglion 
  cells 
  which 
  in 
  this 
  animal 
  are 
  situated 
  in 
  or 
  near 
  the 
  center 
  of 
  

   the 
  brain. 
  In 
  the 
  last 
  abdominal 
  ganglion 
  also 
  the 
  fibers 
  arising 
  from 
  

   the 
  peripheral 
  ganglion 
  cells 
  can 
  very 
  plainly 
  be 
  seen 
  passing 
  in 
  towards 
  

   the 
  center 
  of 
  the 
  ganglion 
  and 
  mingling 
  with 
  the 
  fibers 
  forming 
  it. 
  Hence 
  

   in 
  all 
  probability 
  the 
  fibrous 
  mass 
  of 
  the 
  central 
  part 
  of 
  the 
  brain 
  mostly 
  

   originates 
  from 
  the 
  peripheral 
  or 
  cortical 
  ganglion 
  cells. 
  

  

  To 
  briefly 
  describe 
  the 
  brain 
  of 
  the 
  locust, 
  it 
  is 
  a 
  modified 
  ganglion, 
  

   but 
  structurally 
  entirely 
  different 
  from 
  and 
  far 
  more 
  complicated 
  than 
  

   the 
  other 
  ganglia 
  of 
  the 
  nervous 
  system. 
  It 
  possesses 
  a 
  " 
  central 
  body," 
  

   and 
  in 
  each 
  hemisphere 
  a 
  " 
  mushroom 
  body," 
  optic 
  lobe, 
  and 
  optic 
  gan- 
  

   glion, 
  and 
  olfactory 
  lobe, 
  with 
  their 
  connecting 
  and 
  commissural 
  nerve 
  

   fibers, 
  not 
  found 
  in 
  the 
  other 
  ganglia. 
  In 
  the 
  succeeding 
  ganglia 
  the 
  

   lobes 
  are 
  in 
  general 
  motor; 
  the 
  fibers 
  composing 
  the 
  oesophageal 
  commis- 
  

   sures, 
  and 
  which 
  arise 
  from 
  the 
  oesophageal 
  commissural 
  lobes, 
  extend 
  

   not 
  only 
  to 
  the 
  subcesophageal 
  ganglion, 
  but 
  pass 
  along 
  through 
  the 
  suc- 
  

   ceeding 
  ganglia 
  to 
  the 
  last 
  pair 
  of 
  abdominal 
  nerve 
  centers. 
  326 
  Since, 
  

   then, 
  there 
  is 
  a 
  direct 
  continuity 
  in 
  the 
  fibers 
  forming 
  the 
  two 
  main 
  lon- 
  

   gitudinal 
  commissures 
  of 
  the 
  nervous 
  cord, 
  and 
  which 
  originate 
  in 
  the 
  

   brain, 
  it 
  seems 
  to 
  follow 
  that 
  the 
  movements 
  of 
  the 
  body 
  are 
  in 
  large 
  

   part 
  directed 
  or 
  co-ordinated 
  by 
  the 
  brain. 
  327 
  Still, 
  however, 
  a 
  second 
  

   brain, 
  so 
  to 
  speak, 
  is 
  found 
  in 
  the 
  third 
  thoracic 
  ganglion 
  of 
  the 
  locust, 
  

   which 
  receives 
  the 
  auditory 
  nerves 
  from 
  the 
  ears 
  situated 
  in 
  the 
  base 
  of 
  

   the 
  abdomen 
  ; 
  or 
  in 
  the 
  first 
  thoracic 
  ganglion 
  of 
  the 
  green 
  grasshoppers 
  

   (katydids, 
  &c), 
  whose 
  ears 
  are 
  in 
  their 
  fore 
  legs 
  ; 
  while 
  even 
  the 
  last 
  ab- 
  

   dominal 
  ganglion 
  in 
  the 
  cockroach 
  and 
  mole 
  cricket 
  is, 
  so 
  to 
  speak, 
  a 
  sec- 
  

   ondary 
  brain, 
  since 
  it 
  receives 
  sensory 
  nerves 
  from 
  the 
  caudal 
  stylets 
  

   which 
  are 
  provided 
  with 
  sense 
  organs. 
  

  

  Description 
  of 
  the 
  sections 
  of 
  the 
  brain. 
  — 
  We 
  will 
  now 
  describe 
  the 
  sec- 
  

   tions 
  upon 
  which 
  the 
  subsequent 
  account 
  of 
  the 
  brain 
  is 
  founded. 
  The 
  

   sections, 
  unless 
  otherwise 
  stated, 
  are 
  frontal, 
  i. 
  e., 
  cut 
  transversely 
  across 
  

  

  326 
  We 
  have 
  seen 
  that 
  the 
  two 
  great 
  longitudinal 
  commissures 
  pass 
  directly 
  from 
  the 
  Drain 
  into 
  and 
  then 
  

   pass 
  backward 
  from 
  the 
  subcesophageal 
  ganglion, 
  but 
  beyond 
  that 
  point 
  have 
  not 
  traced 
  their 
  course, 
  

   as 
  it 
  is 
  generally 
  supposed 
  that 
  they 
  extend 
  uninterruptedly 
  to 
  the 
  last 
  abdominal 
  ganglia. 
  This 
  has 
  

   indeed 
  been 
  shown 
  to 
  be 
  the 
  case 
  by 
  Michels 
  in 
  his 
  admirable 
  treatise 
  on 
  the 
  nervous 
  system 
  of 
  a 
  beetle 
  

   (Oryctes) 
  in 
  Siebold 
  and 
  Kolliker's 
  Zeitschrift 
  fur 
  wissen 
  . 
  Zoologie, 
  Band 
  34, 
  Heft. 
  4, 
  1880. 
  Michels 
  

   states 
  that 
  each 
  commissure 
  is 
  formed 
  of 
  three 
  parallel 
  bundles 
  of 
  elementary 
  nerve 
  fibers, 
  which 
  pass 
  

   continuously 
  from 
  one 
  end 
  of 
  the 
  ventral 
  or 
  nervous 
  cord 
  to 
  the 
  other. 
  "The 
  commissures 
  take 
  their 
  

   origin 
  neither 
  out 
  of 
  a 
  central 
  ' 
  ' 
  punct 
  substanz 
  (or 
  marksubstanz), 
  nor 
  from 
  the 
  peripheral 
  ganglion 
  cells 
  

   of 
  the 
  several 
  ganglia, 
  but 
  are 
  mere 
  continuations 
  of 
  the 
  longitudinal 
  fibers 
  which 
  decrease 
  posteriorly 
  

   in 
  thickness, 
  and 
  extend 
  anteriorly 
  through 
  the 
  commissures 
  forming 
  the 
  oesophageal 
  ring 
  to 
  the 
  

   brain." 
  

  

  327 
  The 
  following 
  extract 
  from 
  Newton's 
  paper 
  shows, 
  however, 
  that 
  the 
  infra 
  or 
  subcesophageal 
  gan- 
  

   glion, 
  according 
  to 
  Faivre, 
  has 
  the 
  power 
  of 
  co-ordinating 
  the 
  movements 
  of 
  the 
  body 
  ; 
  still 
  it 
  seems 
  

   to 
  us 
  that 
  the 
  brain 
  may 
  be 
  primarily 
  concerned 
  in 
  the 
  exercise 
  of 
  this 
  power, 
  as 
  the 
  nerves 
  from 
  the 
  

   subcesophageal 
  ganglion 
  supply 
  only 
  the 
  mouth 
  parts. 
  "The 
  physiological 
  experiments 
  of 
  Faivre 
  in 
  1 
  857 
  

   (Ann. 
  J. 
  Sci. 
  Nat., 
  torn, 
  viii, 
  p. 
  245), 
  upon 
  the 
  brain 
  of 
  Dytiscus 
  in 
  relation 
  to 
  locomotion, 
  are 
  of 
  very 
  

   considerable 
  interest, 
  showing, 
  as 
  they 
  appear 
  to 
  do, 
  that 
  the 
  power 
  of 
  co-ordinating 
  the 
  movements 
  of 
  

   the 
  body 
  is 
  lodged 
  in 
  the 
  infra-cesophageal 
  ganglion. 
  And 
  such 
  being 
  the 
  case, 
  both 
  the 
  upper 
  and 
  

   lower 
  pairs 
  of 
  ganglia 
  ought 
  to 
  be 
  regarded 
  as 
  forming 
  parts 
  of 
  the 
  insect's 
  brain." 
  Quart. 
  Jour. 
  Micr. 
  

   Sc, 
  1879, 
  p. 
  342. 
  

  

  