﻿204 
  REPORT 
  UNITED 
  STATES 
  ENTOMOLOGICAL 
  COMMISSION. 
  

  

  great 
  many 
  cells 
  or 
  spermatozoa, 
  the 
  dark 
  portions 
  indicating, 
  however, 
  

   only 
  the 
  heads 
  of 
  the 
  zoosperms, 
  the 
  tails 
  being 
  many 
  times 
  longer, 
  but 
  

   very 
  pale 
  ; 
  it 
  will 
  be 
  noticed 
  that 
  the 
  shape 
  of 
  the 
  bundles 
  changes 
  from 
  

   above 
  downwards, 
  being 
  broad 
  with 
  rounded 
  ends 
  in 
  the 
  upper 
  part, 
  

   and 
  becoming 
  narrower 
  and 
  sharply 
  pointed 
  lower 
  down. 
  In 
  the 
  third 
  

   segment 
  [III] 
  the 
  interior 
  of 
  the 
  tube 
  is 
  entirely 
  filled 
  up 
  with 
  the 
  long 
  

   tails 
  of 
  the 
  spermatozoa, 
  the 
  tails 
  belonging 
  to 
  each 
  set 
  of 
  heads 
  being 
  

   themselves 
  gathered 
  into 
  a 
  sinuous 
  bundle, 
  which 
  are 
  perhaps 
  fifteen 
  or 
  

   twenty 
  times 
  as 
  long 
  as 
  the 
  bundles 
  of 
  the 
  heads. 
  Finally, 
  the 
  fourth 
  

   segment 
  is 
  filled 
  with 
  globules 
  of 
  various 
  sizes, 
  highly 
  colored 
  by 
  the 
  

   haematoxiline, 
  very 
  slightly 
  refringent, 
  and 
  closely 
  crowded 
  together, 
  

   leaving 
  room 
  only 
  for 
  small 
  interspaces 
  and 
  a 
  few 
  bundles 
  of 
  spermatozoa 
  

   tails 
  which 
  extend 
  down 
  among 
  them. 
  

  

  Before 
  entering 
  into 
  the 
  description 
  of 
  various 
  details, 
  which 
  can 
  be 
  

   studied 
  on 
  the 
  isolated 
  tube, 
  I 
  will 
  describe 
  a 
  transverse 
  section 
  through 
  

   the 
  upper 
  part 
  of 
  the 
  first 
  segment, 
  such 
  a 
  section 
  as 
  is 
  represented 
  in 
  

   Fig. 
  24. 
  The 
  whole 
  tube 
  is 
  formed 
  by 
  an 
  external 
  membrane, 
  Tw., 
  and 
  

   its 
  interior 
  is 
  divided 
  up 
  by 
  septae, 
  cys., 
  into 
  several 
  distinct 
  cavities, 
  the 
  

   spermatocysts, 
  each 
  of 
  which 
  contains 
  a 
  number 
  of 
  cellular 
  elements, 
  the 
  

   spermatoblasts 
  j 
  all 
  in 
  about 
  the 
  same 
  stage 
  of 
  development. 
  In 
  the 
  

   walls 
  of 
  the 
  spermatocysts 
  there 
  are 
  a 
  number 
  of 
  peculiar 
  nuclei, 
  so 
  

   flattened 
  that 
  in 
  a 
  transverse 
  section 
  they 
  appear 
  as 
  hardly 
  more 
  than 
  

   a 
  narrow 
  dark 
  line, 
  as 
  is 
  indicated 
  in 
  the 
  figure. 
  The 
  cells 
  of 
  the 
  sperm- 
  

   atoblasts 
  are 
  large 
  and 
  distinct, 
  and 
  are 
  destined 
  to 
  be 
  transformed 
  each 
  

   one 
  into 
  one 
  or 
  more 
  spermatozoa. 
  Near 
  the 
  top 
  of 
  the 
  tube 
  the 
  sperm- 
  

   atoblasts 
  are 
  round 
  cells, 
  the 
  protoplasm 
  of 
  which 
  is 
  highly 
  tinged 
  with 
  

   haeniatoxiline, 
  and 
  which 
  are 
  provided 
  with 
  a 
  bulky 
  central 
  nucleus 
  each, 
  

   as 
  is 
  shown 
  in 
  Fig. 
  26. 
  The 
  nuclei 
  are 
  approximately 
  spherical 
  and 
  very 
  

   coarsely 
  granular, 
  the 
  granulations 
  being 
  dyed 
  almost 
  black 
  by 
  hsema- 
  

   toxiline. 
  Judging 
  from 
  the 
  analogy 
  with 
  other 
  animals, 
  the 
  parts 
  just 
  

   described 
  must 
  be 
  interpreted 
  as 
  follows 
  : 
  The 
  whole 
  of 
  each 
  spermato- 
  

   eyst 
  arises 
  from 
  a 
  single 
  cell, 
  in 
  which 
  the 
  original 
  single 
  nucleus 
  gives 
  

   rise 
  by 
  division 
  to 
  the 
  secondary 
  nuclei, 
  each 
  of 
  which 
  becomes 
  a 
  sperm- 
  

   atoblast, 
  the 
  original 
  cell 
  enlarging 
  until 
  it 
  becomes 
  a 
  cyst 
  ; 
  the 
  mother 
  

   nucleus 
  also 
  divides 
  into 
  nuclei 
  like 
  itself, 
  which 
  become 
  transformed 
  

   into 
  the 
  peculiar 
  nuclei 
  before 
  mentioned, 
  in 
  the 
  wall 
  of 
  the 
  cyst. 
  This 
  

   is 
  of 
  course 
  all 
  hypothetical, 
  not 
  based 
  upon 
  direct 
  observation, 
  for 
  in 
  

   all 
  the 
  seminiferous 
  tubes 
  I 
  have 
  had 
  an 
  opportunity 
  of 
  examining 
  the 
  

   cysts 
  and 
  spermatoblasts 
  were 
  all 
  fully 
  formed. 
  The 
  most 
  complete 
  and 
  

   satisfactory 
  account 
  which 
  I 
  am 
  acquainted 
  with 
  of 
  the 
  development 
  of 
  

   the 
  spermatozoon 
  is 
  that 
  given 
  of 
  the 
  frog 
  by 
  La 
  Vallette. 
  283 
  I 
  would 
  

   also 
  refer 
  those 
  who 
  wish 
  to 
  understand 
  the 
  great 
  theoretical 
  importance 
  

   of 
  these 
  facts 
  to 
  the 
  brief 
  summary 
  of 
  the 
  observations 
  previously 
  made, 
  

   which 
  I 
  have 
  published 
  elsewhere. 
  284 
  

  

  283 
  La 
  Vallette: 
  Archiv 
  fur 
  Mikros. 
  Anat., 
  Bd. 
  xii, 
  s. 
  797, 
  Taf. 
  xxiv, 
  xxxv 
  (1876). 
  

   ™ 
  x 
  Minot: 
  Theory 
  of 
  Impregnation. 
  Troc. 
  Boston 
  S. 
  N. 
  H., 
  1877, 
  vol. 
  xix, 
  p. 
  163. 
  

  

  