﻿STRUCTURE 
  OF 
  THE 
  MALE 
  DUCTS. 
  207 
  

  

  I 
  think 
  these 
  nuclei 
  are 
  probably 
  the 
  degenerating 
  remains 
  of 
  the 
  nuclei 
  

   in 
  the 
  walls 
  of 
  the 
  speruiatocysts, 
  and 
  which 
  I 
  regard 
  as 
  the 
  mother 
  

   nuclei 
  of 
  the 
  spermatoblasts. 
  

  

  Vasa 
  deferentia 
  of 
  locusts. 
  — 
  These 
  are 
  long, 
  nearly 
  cylindrical 
  tubes, 
  

   the 
  walls 
  of 
  which 
  are 
  composed 
  of 
  an 
  interior 
  lining 
  epithelium 
  and 
  an 
  

   external 
  layer 
  hardly 
  one-fourth 
  as 
  thick 
  as 
  the 
  epithelium, 
  and 
  com- 
  

   posed 
  of 
  connective 
  tissue 
  and 
  tracheae, 
  and, 
  as 
  far 
  as 
  I 
  have 
  been 
  able 
  

   to 
  observe, 
  entirely 
  without 
  muscular 
  fibres. 
  The 
  epithelium 
  is 
  formed 
  

   of 
  cylindrical 
  cells, 
  with 
  large 
  and 
  distinct 
  nuclei 
  in 
  the 
  basal 
  third 
  of 
  

   each 
  cell. 
  It 
  is 
  interesting 
  to 
  compare 
  these 
  ducts 
  with 
  the 
  correspond- 
  

   ing 
  canals 
  of 
  Crustacea, 
  the 
  histology 
  of 
  which 
  has 
  been 
  recently 
  studied 
  

   by 
  Grobben 
  289 
  and 
  by 
  August 
  Gruber. 
  290 
  It 
  now 
  seems 
  probable 
  that 
  fur- 
  

   ther 
  observations 
  will 
  soon 
  render 
  it 
  possible 
  to 
  give 
  a 
  description 
  of 
  the 
  

   minute 
  structure 
  of 
  the 
  male 
  ducts 
  which 
  shall 
  correctly 
  record 
  the 
  typ- 
  

   ical 
  form 
  among 
  arthropods. 
  

  

  Ductus 
  cjaculatorius 
  of 
  locusts. 
  — 
  If 
  we 
  make 
  a 
  transverse 
  section 
  

   through 
  the 
  abdomen 
  of 
  a 
  male 
  C. 
  femur-rubrum 
  at 
  the 
  level 
  where 
  the 
  

   ejaculatory 
  duct 
  runs 
  straight 
  along 
  underneath 
  the 
  dorsum 
  a 
  section 
  of 
  

   the 
  duct 
  will 
  be 
  obtained 
  of 
  the 
  appearance 
  indicated 
  in 
  the 
  unfinished 
  

   drawing 
  Fig. 
  33. 
  The 
  canal 
  of 
  the 
  duct, 
  Ej. 
  D, 
  is 
  oval. 
  Below, 
  on 
  either 
  

   side, 
  is 
  the 
  section 
  of 
  a 
  large 
  trachea, 
  Tr. 
  and 
  Tr 
  l 
  . 
  The 
  duct 
  itself 
  is 
  

   lined 
  by 
  an 
  epithelium, 
  Ep., 
  the 
  height 
  of 
  which 
  is 
  very 
  great 
  at 
  the 
  

   sides 
  of, 
  but 
  inconsiderable 
  above 
  and 
  below 
  the 
  duct, 
  so 
  that 
  while 
  the 
  

   cavity 
  appears 
  oval 
  in 
  section 
  the 
  external 
  outline 
  of 
  the 
  epithelium 
  is 
  

   more 
  nearly 
  circular. 
  Above 
  and 
  below, 
  where 
  the 
  epithelium 
  is 
  nar- 
  

   row, 
  there 
  is 
  but 
  a 
  single 
  row 
  of 
  nuclei, 
  but 
  in 
  the 
  broad 
  lateral 
  portions 
  

   the 
  nuclei 
  are 
  at 
  very 
  various 
  levels, 
  though 
  never 
  outside 
  a 
  certain 
  cen- 
  

   tral 
  zone 
  of 
  the 
  cells, 
  so 
  that 
  just 
  below 
  the 
  inner, 
  and 
  likewise 
  the 
  

   outer, 
  surface 
  of 
  the 
  epithelium 
  there 
  is 
  a 
  clear 
  space 
  in 
  which 
  there 
  lie 
  

   no 
  nuclei. 
  The 
  epithelium 
  is 
  surrounded 
  by 
  a 
  muscular 
  coat, 
  Muc, 
  of 
  

   circular 
  fibres, 
  which 
  form 
  a 
  layer 
  of 
  considerable 
  thickness. 
  This 
  coat, 
  

   as 
  will 
  be 
  seen 
  from 
  the 
  figure, 
  is 
  not 
  really 
  separated 
  by 
  the 
  neighbor- 
  

   ing 
  connective 
  tissue. 
  In 
  fact, 
  the 
  external 
  limits 
  of 
  the 
  wall 
  of 
  the 
  duct 
  

   are 
  not 
  defined. 
  

  

  Ycsiculae 
  seminales 
  of 
  locusts. 
  — 
  These 
  are 
  blind 
  cylindrical 
  tubes 
  of 
  

   larger 
  diameter 
  than 
  the 
  vasa 
  deferentia. 
  They 
  consist 
  of 
  an 
  upper, 
  

   wider, 
  non-muscular, 
  and 
  a 
  narrower 
  lower 
  division 
  that 
  has 
  a 
  muscular 
  

   coat. 
  The 
  passage 
  from 
  the 
  upper 
  to 
  the 
  lower 
  portion 
  is 
  gradual, 
  not 
  

   sudden. 
  

  

  A 
  section 
  through 
  the 
  upper 
  part, 
  Fig. 
  31, 
  shows 
  that 
  its 
  walls 
  are 
  

   formed 
  mainly 
  by 
  a 
  cylindrical 
  epithelium, 
  with 
  slightly 
  oval 
  nuclei, 
  

   nearly 
  in 
  the 
  center 
  of 
  each 
  cell. 
  I 
  think, 
  but 
  am 
  not 
  sure, 
  that 
  the 
  nu- 
  

   clei 
  are 
  nucleolated. 
  There 
  is 
  a 
  delicate 
  interior 
  cuticula. 
  I 
  thought 
  

  

  289 
  Grobben 
  : 
  Beitrage 
  zur 
  Kenntniss 
  der 
  mannl. 
  Gescklechtsorg. 
  der 
  Docapoden; 
  etc. 
  Arb. 
  Zool. 
  Inst. 
  

   Wien. 
  (1878). 
  

  

  290 
  A. 
  Gruber: 
  TTber 
  zwei 
  Siisswasser 
  Calaniden, 
  Leipzig, 
  1878. 
  Beitrage- 
  zur 
  Kenntniss 
  der 
  Genera- 
  

   tionsorgane 
  der 
  freilebenden 
  Copepoden. 
  Z. 
  Z., 
  xxxii 
  (18T9), 
  p. 
  407. 
  

  

  