﻿MUSCLES 
  OF 
  THE 
  LOCUST. 
  195 
  

  

  fined 
  to 
  the 
  larger 
  branches. 
  My 
  observations 
  on 
  the 
  grasshoppers 
  en- 
  

   tirely 
  confirm 
  Lubbock's 
  opinion, 
  and 
  probably 
  his 
  conclusion 
  may 
  be 
  

   safely 
  made 
  general 
  for 
  all 
  insects. 
  

  

  Air-sacks 
  and 
  spiracles. 
  — 
  Concerniug 
  the 
  latter 
  I 
  have 
  made 
  no 
  obser- 
  

   vations, 
  considering 
  that 
  an 
  account 
  of 
  their 
  structure 
  belongs 
  rather 
  

   to 
  the 
  anatomist. 
  Of 
  the 
  air-sacks 
  I 
  have 
  only 
  to 
  say 
  that 
  in 
  them 
  the 
  

   spiral 
  filament 
  is 
  wanting, 
  their 
  inner 
  walls 
  being 
  thrown 
  up 
  into 
  quite 
  

   high 
  and 
  somewhat 
  irregular 
  folds, 
  but 
  concerning 
  the 
  histological 
  ele- 
  

   ments 
  of 
  the 
  sacks 
  I 
  can 
  add 
  nothing 
  to 
  what 
  is 
  already 
  known. 
  The 
  

   absence 
  of 
  the 
  spiral 
  thread 
  had 
  already 
  been 
  noticed 
  by 
  the 
  older 
  

   authors. 
  254 
  The 
  true 
  air-sacks 
  must 
  be 
  distinguished 
  from 
  simple 
  tracheal 
  

   dilatations. 
  

  

  MUSCLES. 
  

  

  By 
  far 
  the 
  majority 
  of 
  the 
  muscular 
  fibres 
  in 
  Caloptenus 
  and 
  (Edipoda 
  

   are 
  transversely 
  striated. 
  Examined 
  with 
  a 
  high 
  power 
  they 
  are 
  found 
  

   to 
  resemble 
  closely 
  the 
  fibres 
  of 
  the 
  common 
  water-beetle, 
  which 
  has 
  been 
  

   so 
  often 
  figured 
  and 
  studied. 
  255 
  First 
  there 
  is 
  a 
  broad 
  

   dark 
  band, 
  then 
  a 
  broad 
  light 
  band, 
  which 
  is, 
  however, 
  

   divided 
  in 
  two 
  by 
  a 
  narrow 
  dark 
  line, 
  just 
  as 
  in 
  the 
  

   fibres 
  of 
  Hydropltilus, 
  figured 
  in 
  the 
  accompanying 
  wood- 
  

   cut. 
  

  

  The 
  way 
  in 
  which 
  the 
  muscular 
  fibres 
  are 
  grouped 
  

   together 
  varies 
  very 
  much 
  in 
  different 
  parts 
  of 
  the 
  body. 
  

   For 
  instance, 
  in 
  some 
  of 
  the 
  muscles 
  of 
  the 
  head 
  the 
  

   fibres 
  are 
  not 
  collected 
  in 
  bundles, 
  but 
  are 
  more 
  or 
  less 
  

   isolated, 
  as 
  appears 
  with 
  the 
  utmost 
  distinctness 
  in 
  a 
  

  

  Fig. 
  8. 
  — 
  Muscular 
  . 
  

  

  fibre 
  of 
  Hydropiiiius 
  transverse 
  section 
  like 
  Fig. 
  5, 
  while 
  the 
  muscles 
  of 
  the 
  

   piceus.-AfterMinot. 
  thorax 
  form 
  bundles 
  of 
  more 
  or 
  less 
  cylindrical 
  form, 
  as 
  

   appears 
  in 
  Figs. 
  9 
  and 
  6 
  r. 
  m. 
  The 
  single 
  fibres 
  are 
  not 
  round, 
  as 
  might 
  

   be 
  thought 
  upon 
  looking 
  at 
  one 
  spread 
  out 
  longitudinally, 
  but 
  polygonal 
  

   in 
  section, 
  as 
  is 
  seen 
  in 
  Fig. 
  5, 
  the 
  corners 
  being 
  rounded 
  off. 
  They 
  are 
  

   commonly 
  four-sided, 
  but 
  sometimes 
  three 
  or 
  five-sided. 
  In 
  every 
  mus- 
  

   cular 
  bundle 
  there 
  are 
  to 
  be 
  seen 
  oval 
  nuclei, 
  whose 
  long 
  axes 
  lie 
  more 
  

   or 
  less 
  nearly 
  parallel 
  with 
  the 
  direction 
  of 
  the 
  muscular 
  fibres. 
  The 
  

   nuclei 
  are 
  small 
  and 
  flattened, 
  slightly 
  granular, 
  and 
  many 
  of 
  them 
  (Fig. 
  

   9) 
  contain 
  a 
  small 
  eccentric 
  nucleolus. 
  They 
  are 
  situated 
  on 
  the 
  surface 
  

   of 
  the 
  fibres, 
  to 
  which 
  I 
  think 
  they 
  belong, 
  though 
  they 
  are 
  perhaps 
  

   the 
  nuclei 
  of 
  the 
  sarcolemma. 
  

  

  Besides 
  the 
  striated 
  muscles 
  there 
  are 
  also 
  smooth 
  fibres 
  to 
  be 
  found 
  

   around 
  the 
  intestine, 
  as 
  will 
  be 
  more 
  particularly 
  described 
  hereafter. 
  

  

  ^Burmeister: 
  Manual 
  of 
  Entomology, 
  translated 
  by 
  Shuckard, 
  p. 
  ITS. 
  

  

  ^Ranvicr: 
  Traite 
  Technique 
  d' 
  Histologic, 
  p. 
  477 
  ff. 
  

  

  Br. 
  T. 
  Dvnght: 
  Structure 
  and 
  action 
  of 
  striated 
  muscular 
  fibre; 
  in 
  the 
  Proc. 
  Boston 
  S. 
  X. 
  H. 
  (1873- 
  

   "74), 
  vol. 
  xvi, 
  p. 
  119. 
  

  

  Engdmann 
  : 
  Pliiger's 
  Archiv. 
  fur 
  Physiologie, 
  Bd. 
  vii, 
  pp. 
  33 
  and 
  155, 
  and 
  Bd. 
  xviii, 
  p. 
  1, 
  and 
  : 
  

   others. 
  

  

  