﻿THE 
  BRAIN 
  OF 
  THE 
  LOCUST. 
  237 
  

  

  stage 
  shows, 
  in 
  place 
  of 
  the 
  calices, 
  four 
  symmetrically 
  situated 
  balls 
  of 
  

  

  much 
  smaller 
  size 
  : 
  the 
  central 
  body 
  was 
  very 
  flat, 
  and 
  the 
  other 
  parts 
  

   were 
  wanting. 
  In 
  the 
  pupa 
  all 
  the 
  parts 
  had 
  attained 
  their 
  definite 
  

   shape. 
  It 
  appears 
  from 
  his 
  observations 
  that 
  the 
  calices 
  are 
  the 
  last 
  to 
  

   be 
  developed. 
  

  

  He 
  then 
  gives 
  the 
  results 
  of 
  his 
  examination 
  of 
  the 
  brain 
  of 
  caterpil- 
  

   lars, 
  as 
  compared 
  with 
  that 
  of 
  the 
  adult 
  sphinx 
  moth. 
  In 
  a 
  caterpillar 
  

   examined 
  near 
  the 
  time 
  of 
  pupation, 
  the 
  central 
  body 
  is 
  very 
  much 
  un- 
  

   developed, 
  forming 
  a 
  small 
  linear 
  transverse 
  body 
  (Querleiste), 
  while 
  the 
  

   different 
  parts 
  of 
  the 
  mushroom 
  body 
  are 
  indicated. 
  In 
  smaller 
  cater- 
  

   pillars 
  it 
  is 
  scarcely 
  possible 
  to 
  work 
  out 
  the 
  development 
  of 
  the 
  brain. 
  

   In 
  that 
  of 
  Pontia 
  bra&suxE 
  the 
  mushroom 
  body 
  and 
  central 
  body 
  were 
  

   undeveloped, 
  while 
  in 
  that 
  of 
  an 
  Euprepia 
  larva 
  the 
  double 
  stalk 
  of 
  

   the 
  mushroom 
  body 
  was 
  developed 
  as 
  well 
  as 
  roundish 
  calyx 
  masses. 
  

   But 
  in 
  a 
  Noctuid 
  larva 
  the 
  entire 
  mushroom 
  body, 
  including 
  well-devel- 
  

   oped 
  trabecule 
  and 
  a 
  very 
  flat 
  central 
  body, 
  was 
  present. 
  

  

  The 
  brain 
  of 
  the 
  mature 
  pupae 
  of 
  Lepidoptera, 
  for 
  example 
  Sat 
  urn 
  ia 
  

   carpini, 
  contains 
  all 
  the 
  portions 
  of 
  the 
  adult 
  brain, 
  and 
  in 
  the 
  same 
  

   relative 
  proportions. 
  But 
  a 
  brain 
  of 
  Sphinx 
  lignstri, 
  in 
  a 
  considerably 
  

   younger 
  stage 
  of 
  development, 
  did 
  not 
  differ 
  much 
  from 
  the 
  brain 
  of 
  the 
  

   larva. 
  

  

  We 
  offer 
  the 
  following 
  observations 
  on 
  the 
  brain 
  of 
  the 
  embryo 
  locust, 
  

   shortly 
  before 
  hatching, 
  with 
  much 
  diffidence, 
  as 
  we 
  are 
  liable 
  to 
  be 
  cor- 
  

   rected 
  by 
  future 
  observations 
  in 
  the 
  same 
  directions. 
  The 
  embryos 
  

   were 
  taken 
  from 
  the 
  egg-shell, 
  hardened 
  in 
  the 
  usual 
  manner, 
  and 
  then 
  

   cut 
  by 
  Mr. 
  Mason, 
  the 
  sections 
  being 
  frontal, 
  the 
  entire 
  insect 
  being 
  

   embedded 
  in 
  a 
  mixture 
  of 
  paraffine, 
  wax, 
  and 
  oil. 
  

  

  In 
  the 
  youngest 
  stage 
  (which 
  we 
  will 
  call 
  stage 
  A) 
  observed, 
  the 
  body 
  

   and 
  appendages 
  were 
  formed 
  and 
  the 
  eyes 
  with 
  their 
  facets, 
  the 
  pigment 
  

   mass 
  coloring 
  the 
  cornea 
  pale 
  reddish. 
  

  

  At 
  this 
  stage, 
  as 
  seen 
  in 
  section 
  7 
  (PI. 
  XII, 
  Fig. 
  1), 
  the 
  antennal 
  and 
  

   optic 
  lobes 
  of 
  the 
  brain 
  are 
  indicated, 
  but 
  the 
  central 
  body 
  and 
  mush- 
  

   room 
  bodies 
  are 
  not 
  yet 
  differentiated. 
  In 
  a 
  plane 
  lying 
  in 
  front 
  of 
  the 
  

   optic 
  and 
  antennal 
  lobes, 
  the 
  brain 
  is 
  divided 
  in 
  each 
  hemisphere 
  into 
  two 
  

   regions 
  or 
  lobes, 
  i. 
  e., 
  an 
  upper 
  (Figs. 
  1 
  and 
  8, 
  up 
  I) 
  and 
  lower 
  cerebral 
  lobe 
  

   (low 
  I). 
  From 
  these 
  embryonic 
  cerebral 
  lobes 
  are 
  eventually 
  developed 
  

   the 
  central 
  body 
  and 
  the 
  two 
  mushroom 
  bodies. 
  The 
  stratum 
  of 
  cortical 
  

   ganglionic 
  cells 
  is, 
  at 
  this 
  period, 
  quite 
  distinct 
  from 
  the 
  paler 
  unstained 
  

   granular 
  brain 
  matter. 
  PL 
  XII, 
  Fig. 
  1 
  a, 
  represents 
  the 
  structure 
  of 
  the 
  

   ganglionic 
  cell-portion, 
  which 
  gradually 
  passes 
  into 
  the 
  central 
  white 
  brain 
  

   substance, 
  which 
  is 
  composed 
  of 
  fine 
  granules 
  or 
  nuclei 
  alone, 
  and 
  which 
  

   do 
  not 
  apparently 
  differ 
  from 
  the 
  granules 
  scattered 
  among 
  the 
  ganglion 
  

   cells. 
  It 
  is 
  to 
  be 
  observed 
  that 
  there 
  are 
  no 
  fibers 
  among 
  the 
  granules. 
  

   It 
  thus 
  appears 
  that 
  the 
  brain 
  of 
  insects, 
  like 
  the 
  other 
  ganglia, 
  origi- 
  

   nally 
  consists 
  of 
  a 
  paler 
  portion 
  formed 
  of 
  fine 
  clear 
  granules 
  (nuclei?), 
  

   enveloped 
  by 
  a 
  thick 
  irregular 
  layer 
  of 
  nucleated 
  cells, 
  containing 
  fine 
  

   granules 
  outside 
  of 
  the 
  nucleus. 
  

  

  