﻿206 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  Since 
  the 
  peculiar 
  cells 
  of 
  Fig. 
  27 
  are 
  signs 
  of 
  division 
  they 
  are 
  not 
  

   always 
  present, 
  but 
  in 
  some 
  tubes 
  they 
  are 
  absent 
  altogether. 
  The 
  mul- 
  

   tiplication 
  of 
  the 
  spermatoblasts 
  by 
  self-division 
  is 
  interesting 
  because 
  

   it 
  shows 
  that 
  all 
  the 
  male 
  elements 
  do 
  not 
  arise 
  directly 
  from 
  the 
  mother 
  

   nucleus, 
  a 
  fact 
  of 
  most 
  profound 
  theoretical 
  meaning. 
  

  

  We 
  must 
  now 
  pass 
  to 
  the 
  consideration 
  of 
  the 
  alterations 
  of 
  form 
  which 
  

   the 
  spermatoblasts 
  undergo 
  after 
  their 
  multiplication 
  ceases. 
  As 
  before 
  

   stated, 
  these 
  changes 
  occur 
  altogether 
  in 
  the 
  second 
  segment 
  of 
  the 
  

   tube.' 
  The 
  body 
  of 
  the 
  spermatoblasts 
  begins 
  to 
  change 
  before 
  the 
  

   nucleus, 
  as 
  is 
  frequently 
  the 
  case 
  with 
  other 
  animals, 
  287 
  and 
  is 
  perhaps 
  

   even 
  the 
  general 
  rule. 
  In 
  the 
  grasshopper 
  the 
  cells 
  begin 
  to 
  elongate, 
  

   the 
  nucleus 
  remaining 
  in 
  the 
  upper 
  part. 
  There 
  remains 
  a 
  small 
  head 
  of 
  

   protoplasm 
  around 
  the 
  nucleus, 
  while 
  the 
  rest 
  of 
  the 
  protoplasm 
  length- 
  

   ens 
  out 
  to 
  form 
  a 
  long 
  tail, 
  so 
  that 
  when 
  the 
  spermatozoon 
  is 
  about 
  half- 
  

   developed 
  it 
  consists 
  of 
  a 
  head 
  with 
  a 
  small, 
  spherical, 
  granulated 
  nucleus 
  

   surrounded 
  by 
  a 
  little 
  protoplasm, 
  which 
  is 
  prolonged 
  into 
  a 
  thread-like 
  

   tail. 
  The 
  further 
  metamorphosis 
  consists 
  mainly 
  in 
  the 
  elongation 
  of 
  

   the 
  nucleus, 
  it 
  first 
  becoming 
  pointed 
  at 
  both 
  ends 
  and 
  bulging 
  in 
  the 
  

   middle, 
  then 
  growing 
  more 
  and 
  more 
  rod-like 
  until 
  it 
  is 
  quite 
  filamen- 
  

   tous 
  and 
  about 
  six 
  times 
  its 
  original 
  length 
  ; 
  meanwhile 
  the 
  protoplasm 
  

   around 
  the 
  nucleus 
  gradually 
  disappears, 
  forming 
  probably 
  the 
  little 
  

   thread 
  that 
  extends 
  beyond 
  the 
  nucleus, 
  and 
  also 
  contributing 
  to 
  the 
  

   growth 
  of 
  the 
  tail. 
  The 
  nucleus, 
  while 
  lengthening 
  out, 
  does 
  not 
  remain 
  

   perfectly 
  straight, 
  but 
  at 
  a 
  certain 
  period 
  of 
  its 
  formation 
  is 
  curved 
  

   somewhat 
  in 
  the 
  form 
  of 
  an 
  S. 
  The 
  nuclei 
  afterwards 
  straighten 
  out 
  

   again 
  forming 
  the 
  heads 
  of 
  the 
  spermatozoa 
  and 
  they 
  then 
  lay 
  them- 
  

   selves 
  parallel 
  to 
  one 
  another, 
  and 
  as 
  they 
  become 
  more 
  perfectly 
  packed 
  

   together 
  they 
  form 
  the 
  sharp-pointed 
  bundles, 
  which 
  are 
  so 
  character- 
  

   istic 
  of 
  the 
  lower 
  part 
  of 
  the 
  second 
  segment 
  of 
  the 
  seminiferous 
  tubes, 
  

   Fig. 
  25, 
  II. 
  In 
  a 
  transverse 
  section 
  through 
  the 
  head 
  of 
  a 
  bundle 
  of 
  

   spermatozoa, 
  the 
  heads 
  appear 
  as 
  minute 
  dots 
  closely 
  crowded 
  together, 
  

   while 
  in 
  a 
  section 
  of 
  a 
  younger 
  bundle, 
  Fig. 
  30, 
  they 
  lie 
  at 
  some 
  distance 
  

   apart. 
  288 
  

  

  There 
  now 
  remain 
  to 
  be 
  mentioned 
  the 
  very 
  singular 
  nuclei 
  which 
  

   appear 
  in 
  the 
  walls 
  of 
  the 
  seminiferous 
  tubes 
  in 
  the 
  lower 
  three-quarters 
  

   of 
  their 
  length. 
  They 
  are 
  irregularly 
  distributed, 
  oval, 
  very 
  much 
  flat- 
  

   tened, 
  quite 
  large, 
  and 
  contain 
  a 
  few 
  large 
  granules, 
  which 
  alone 
  are 
  

   stained 
  by 
  hsematoxiline, 
  the 
  intervening 
  space 
  remaining 
  perfectly 
  clear. 
  

  

  287 
  La 
  Vallette 
  St. 
  George: 
  Der 
  Hoden 
  in 
  Strieker's 
  Handbuch 
  i, 
  p. 
  522, 
  especially 
  figs. 
  183, 
  188, 
  189. 
  

  

  "Oeber 
  die 
  Genese 
  der 
  Samenkorpor. 
  4. 
  Mittkeiluug. 
  Arch. 
  Mikros. 
  Auat., 
  Bd. 
  xii, 
  p. 
  797. 
  

  

  Spengel: 
  1. 
  c. 
  

  

  Braun: 
  Das 
  Urogenital 
  System 
  der 
  einkeimischen 
  Reptilien. 
  Semper's 
  Arbeiten, 
  iv, 
  p. 
  113. 
  Hoden, 
  

   p. 
  158 
  ff. 
  

  

  Kolliker: 
  Handbuck 
  der 
  Gewebelekre, 
  5 
  Aufl., 
  1867, 
  pp. 
  526-528. 
  

  

  Sertoli: 
  Sulla 
  Struthora 
  dclli 
  Canalicoli 
  seminiferi, 
  etc. 
  Arckivio 
  dello 
  Scienzo 
  Medicke, 
  vol. 
  ii, 
  p. 
  

   107 
  (1877). 
  

  

  288 
  For 
  otker 
  accounts 
  of 
  tko 
  development 
  of 
  spermatozoa 
  in 
  insects 
  the 
  reader 
  is 
  referred 
  to 
  H. 
  Meyer, 
  

   Zeit. 
  Wiss. 
  Zool., 
  Bd. 
  i, 
  p. 
  187. 
  

  

  