﻿STRUCTURE 
  OF 
  THE 
  TESTIS. 
  203 
  

  

  receptaculum 
  seminis. 
  A 
  description 
  of 
  the 
  receptaculuin 
  and 
  its 
  ducts 
  

   in 
  Phthirius 
  is 
  given 
  by 
  Graber. 
  281 
  

  

  2. 
  — 
  Male 
  organs. 
  

  

  The 
  close 
  analogy 
  between 
  the 
  male 
  and 
  female 
  genital 
  systems 
  in 
  

   insects 
  is 
  shown 
  by 
  the 
  correspondence 
  of 
  their 
  divisions, 
  and 
  has 
  been 
  

   repeatedly 
  pointed 
  out. 
  The 
  analogy 
  in 
  the 
  way 
  in 
  which 
  the 
  sexual 
  

   products 
  are 
  developed, 
  though 
  attention 
  has 
  been 
  called 
  to 
  it, 
  has 
  not 
  

   been 
  so 
  often 
  emphasized. 
  The 
  testes 
  are 
  elongated 
  sacks 
  or 
  tubes 
  

   whose 
  upper 
  ends 
  terminate 
  blindly 
  and 
  whose 
  lower 
  ends 
  open 
  into 
  

   the 
  efferent 
  ducts. 
  The 
  spermatozoa 
  begin 
  their 
  development 
  in 
  the 
  

   ca3cal 
  end, 
  in 
  which, 
  accordingly, 
  we 
  find 
  the 
  earliest 
  stages 
  always 
  

   represented, 
  while 
  the 
  more 
  advanced 
  zoosperms 
  all 
  lie 
  further 
  down 
  in 
  

   the 
  sack, 
  just 
  as 
  we 
  find 
  the 
  youngest 
  stages 
  of 
  the 
  eggs 
  in 
  the 
  upper, 
  

   the 
  oldest 
  in 
  the 
  lower 
  part 
  of 
  the 
  ovarian 
  tubules. 
  The 
  simplicity 
  

   and 
  distinctness 
  of 
  the 
  parts 
  and 
  straightness 
  of 
  the 
  seminiferous 
  tubes 
  

   in 
  the 
  grasshoppers 
  renders 
  the 
  testes 
  of 
  these 
  insects 
  the 
  very 
  best 
  

   object 
  to 
  demonstrate 
  the 
  development 
  of 
  the 
  spermatozoa, 
  with 
  which 
  

   I 
  am 
  acquainted, 
  as 
  in 
  a 
  single 
  preparation 
  all 
  the 
  principal 
  stages 
  are 
  

   often 
  distinctly 
  shown. 
  

  

  Testis. 
  252 
  — 
  The 
  male 
  glands 
  are 
  composed 
  of 
  tubes 
  which, 
  instead 
  of 
  

   ascending 
  from 
  below 
  forivards 
  as 
  do 
  the 
  ovarian 
  tubes, 
  incline 
  from 
  

   below 
  backicards. 
  The 
  whole 
  set 
  of 
  tubes 
  is 
  inclosed 
  in 
  a 
  common 
  sack- 
  

   like 
  envelope 
  (Fig. 
  G, 
  p. 
  191, 
  testis 
  of 
  Ana^rus), 
  and 
  from 
  this 
  the 
  tubes 
  

   must 
  be 
  isolated. 
  I 
  have 
  found 
  the 
  most 
  convenient 
  way 
  of 
  doing 
  this 
  

   to 
  carefully 
  harden 
  a 
  whole 
  male 
  insect 
  in 
  alcohol, 
  and 
  then 
  to 
  cut 
  the 
  

   whole 
  abdomen 
  in 
  two 
  along 
  the 
  median 
  line, 
  after 
  which 
  if 
  a 
  little 
  

   pains 
  is 
  taken 
  the 
  single 
  seminiferous 
  tubes, 
  which 
  will 
  be 
  easily 
  recog- 
  

   nized 
  lying 
  over 
  the 
  stomach, 
  can 
  be 
  isolated 
  under 
  alcohol 
  with 
  needles. 
  

   The 
  following 
  account 
  refers 
  to 
  locusts 
  only. 
  The 
  general 
  shape 
  of 
  

   one 
  of 
  the 
  tubes 
  is 
  shown 
  in 
  Fig. 
  25. 
  The 
  upper 
  end 
  is 
  rounded 
  off, 
  and 
  

   from 
  the 
  tip 
  downwards 
  it 
  widens 
  very 
  rapidly, 
  the 
  tube 
  soon 
  attaining 
  

   its 
  maximum 
  diameter, 
  which 
  it 
  then 
  maintains 
  through 
  the 
  rest 
  of 
  its 
  

   upper 
  half 
  ; 
  the 
  lower 
  half 
  gradually 
  tapers 
  down 
  to 
  a 
  comparatively 
  

   small 
  tube. 
  The 
  whole, 
  when 
  isolated 
  in 
  the 
  manner 
  described, 
  is 
  

   more 
  or 
  less 
  surrounded 
  by 
  connective 
  tissue, 
  as 
  shown 
  in 
  the 
  drawing, 
  

   conn. 
  The 
  tube 
  may 
  be 
  roughly 
  divided 
  into 
  four 
  segments 
  as 
  indicated 
  

   by 
  the 
  numbered 
  brackets 
  of 
  Fig. 
  25. 
  The 
  upper 
  segment 
  [I] 
  is 
  filled 
  

   with 
  aggregations 
  of 
  cells 
  in 
  various 
  stages 
  of 
  transformation 
  into 
  sper- 
  

   matozoa, 
  but 
  still 
  distinctively 
  cellular 
  in 
  their 
  appearance. 
  In 
  the 
  

   second 
  segment 
  [II] 
  the 
  cells 
  are 
  gathered 
  into 
  distinct 
  bundles, 
  each 
  

   bundle 
  being 
  as 
  shown 
  in 
  the 
  figure 
  in 
  a 
  different 
  stage 
  of 
  development, 
  

   those 
  lowest 
  down 
  being 
  most 
  advanced 
  ; 
  in 
  Fig. 
  25 
  each 
  one 
  of 
  the 
  dark 
  

   masses 
  represents 
  one 
  of 
  the 
  bundles, 
  each 
  of 
  which 
  is 
  composed 
  of 
  a 
  

  

  ™ 
  Graber: 
  Z. 
  Z., 
  xxii 
  (1872), 
  pp. 
  161-162. 
  

  

  282 
  This 
  account 
  of 
  the 
  testis 
  is 
  taken 
  mainly 
  from 
  Caloptenus 
  spretus. 
  

  

  