﻿A 
  Further 
  Study 
  of 
  Chromosome 
  Dimensions. 
  161 
  

  

  Figs. 
  8 
  and 
  9 
  show 
  polar 
  views 
  of 
  the 
  primary 
  spermatocyte 
  metaphase. 
  

   Fig. 
  10 
  shows 
  a 
  lateral 
  view 
  of 
  this 
  metaphase. 
  Fig. 
  11 
  shows 
  a 
  polar 
  view 
  of 
  

   the 
  secondary 
  spermatocyte 
  metaphase. 
  These 
  photo-micrographs 
  closely 
  

   resemble 
  the 
  drawings 
  of 
  Federley 
  of 
  this 
  and 
  allied 
  species, 
  and 
  may 
  there- 
  

   fore 
  be 
  accepted 
  as 
  typical 
  of 
  these 
  moths. 
  

  

  Figs. 
  12 
  to 
  17 
  represent 
  the 
  butterfly, 
  Vanessa 
  urticce. 
  Fig. 
  12 
  shows 
  a 
  

   polar 
  view 
  of 
  the 
  spermatogonial 
  metaphase 
  ; 
  lateral 
  views 
  of 
  this 
  metaphase 
  

   are 
  shown 
  in 
  figs. 
  13 
  and 
  14. 
  Fig. 
  15 
  shows 
  a 
  lateral 
  view 
  of 
  the 
  primary 
  

   spermatocyte 
  metaphase. 
  Figs. 
  16 
  and 
  17 
  show 
  respectively 
  a 
  polar 
  and 
  a 
  

   lateral 
  view 
  of 
  the 
  secondary 
  spermatocyte 
  metaphase. 
  The 
  similarity 
  of 
  

   these 
  photo-micrographs 
  and 
  those 
  of 
  Smerinthus 
  populi 
  proves 
  that 
  the 
  type 
  

   depicted 
  is 
  not 
  exceptional 
  among 
  Lepidoptera. 
  

  

  A 
  comparison 
  of 
  the 
  photo-micrographs 
  of 
  Stenobothrus 
  viridulus 
  with 
  those 
  

   of 
  Smerinthus 
  populi 
  and 
  Vanessa 
  urticce 
  proves 
  that 
  the 
  total 
  volume 
  of 
  

   chromatin 
  on 
  the 
  spindle 
  is 
  much 
  greater 
  in 
  Stenobothrus 
  than 
  in 
  either 
  

   Smerinthus 
  or 
  Vanessa 
  ; 
  this 
  difference 
  is 
  equally 
  evident 
  in 
  the 
  sperma- 
  

   togonial, 
  and 
  primary 
  and 
  secondary 
  spermatocyte 
  mitoses. 
  And 
  the 
  same 
  

   result 
  is 
  obtained 
  from 
  comparison 
  of 
  the 
  chromosome 
  diameters 
  ; 
  for, 
  in 
  each 
  

   cell 
  generation, 
  the 
  diameters 
  in 
  Stenobothrus 
  are 
  obviously 
  much 
  greater 
  

   than 
  those 
  in 
  Smerinthus 
  and 
  Vanessa. 
  This 
  evidence 
  is 
  similar 
  to 
  that 
  

   obtained 
  by 
  Farmer 
  and 
  Digby 
  in 
  Homarus 
  gammarus 
  and 
  Palcemon 
  serratus 
  ; 
  

   but, 
  whereas 
  they 
  observed 
  difference 
  in 
  two 
  animals 
  individually 
  considered, 
  

   the 
  difference 
  now 
  observed 
  is 
  in 
  animals 
  that 
  have 
  been 
  shown 
  to 
  be 
  typical 
  

   of 
  definite 
  groups. 
  

  

  Figs. 
  18 
  to 
  23 
  represent 
  the 
  snail 
  Helix 
  pomatia. 
  Fig. 
  18 
  shows 
  a 
  polar 
  

   view 
  of 
  the 
  spermatogonial 
  metaphase. 
  Figs. 
  19 
  and 
  20 
  show 
  respectively 
  a 
  

   polar 
  and 
  a 
  lateral 
  view 
  of 
  the 
  primary 
  spermatocyte 
  metaphase. 
  Fig. 
  21 
  

   shows 
  a 
  polar 
  view 
  of 
  the 
  secondary 
  spermatocyte 
  metaphase 
  ; 
  while 
  lateral 
  

   views 
  of 
  this 
  metaphase 
  are 
  shown 
  in 
  figs. 
  22 
  and 
  23. 
  The 
  preparations 
  of 
  

   Helix 
  studied 
  in 
  my 
  first 
  paper 
  were 
  lent 
  to 
  me, 
  and 
  I 
  stated 
  at 
  the 
  time 
  

   that 
  I 
  had 
  found 
  few 
  dividing 
  cells, 
  and 
  consequently 
  had 
  been 
  unable 
  to 
  

   measure 
  all 
  chromosomes 
  of 
  the 
  complex. 
  The 
  photo-micrographs 
  now 
  given 
  

   are 
  taken 
  from 
  many 
  preparations 
  that 
  I 
  have 
  since 
  made 
  and 
  studied, 
  and 
  

   I 
  am 
  now 
  able 
  to 
  correct 
  and 
  supplement 
  my 
  earlier 
  observations. 
  I 
  find 
  

   that 
  the 
  two 
  camera 
  lucida 
  drawings 
  that 
  I 
  gave 
  and 
  identified 
  as 
  sperma- 
  

   togonial 
  mitoses 
  must 
  have 
  been 
  made 
  from 
  spermatocyte 
  cells. 
  Fig. 
  18 
  in 
  

   the 
  Plate 
  of 
  the 
  present 
  paper 
  shows 
  a 
  spermatogonial 
  complex 
  ; 
  and 
  the 
  

   chromosome 
  diameters 
  are 
  seen 
  to 
  be 
  smaller 
  than 
  those 
  observed 
  in 
  the 
  

   secondary 
  spermatocyte 
  mitosis, 
  represented 
  by 
  figs. 
  21, 
  22, 
  and 
  23. 
  Such 
  

   difference 
  is 
  not 
  confined 
  to 
  Helix, 
  for 
  I 
  have 
  found 
  it 
  in 
  other 
  animals, 
  

  

  