﻿162 
  

  

  Mr. 
  C. 
  F. 
  U. 
  Meek. 
  

  

  including 
  Felis, 
  in 
  which 
  it 
  has 
  been 
  noted 
  by 
  Dr. 
  de 
  Winiwarter. 
  Lastly, 
  

   the 
  diameters 
  of 
  all 
  chromosomes 
  composing 
  the 
  secondary 
  spermatocyte 
  

   complex 
  are 
  not 
  the 
  same. 
  Within 
  limits, 
  differences 
  in 
  size 
  of 
  chromosomes 
  

   seen 
  in 
  a 
  photo-micrograph 
  of 
  a 
  lateral 
  view 
  do 
  not 
  necessarily 
  prove 
  that 
  

   differences 
  actually 
  exist. 
  All 
  chromosomes 
  of 
  a 
  complex 
  are 
  not 
  in 
  perfect 
  

   focus 
  at 
  the 
  same 
  moment; 
  and 
  chromosomes 
  that 
  are 
  not 
  in 
  perfect 
  focus 
  

   appear 
  in 
  the 
  photo-micrograph 
  to 
  be 
  smaller 
  than 
  they 
  really 
  are. 
  In 
  fig. 
  23, 
  

   however, 
  certain 
  daughter 
  chromosomes 
  that 
  are 
  equally 
  in 
  focus 
  show 
  small 
  

   differences 
  in 
  size 
  and 
  diameter 
  ; 
  and 
  these 
  differences 
  must, 
  therefore, 
  be 
  

   accepted. 
  This 
  evidence 
  of 
  different 
  diameters 
  within 
  a 
  complex 
  corroborates 
  

   the 
  results 
  of 
  Farmer 
  and 
  Digby. 
  

  

  Fig. 
  24 
  shows 
  a 
  polar 
  view 
  of 
  the 
  secondary 
  spermatocyte 
  metapbase 
  in 
  the 
  

   newt, 
  Triton 
  cristatus. 
  

  

  Figs. 
  25 
  to 
  29 
  represent 
  the 
  cat, 
  Felis, 
  and 
  are 
  photo-micrographs 
  that 
  I 
  

   made 
  from 
  Dr. 
  de 
  Winiwarter's 
  preparations. 
  Fig. 
  25 
  shows 
  a 
  polar 
  view 
  of 
  

   the 
  spermatogonial 
  metaphase, 
  while 
  fig. 
  26 
  shows 
  a 
  lateral 
  view 
  of 
  

   the 
  early 
  anaphase 
  of 
  this 
  mitosis. 
  Fig. 
  27 
  shows 
  a 
  polar 
  view 
  of 
  the 
  primary 
  

   spermatocyte 
  metaphase. 
  Lateral 
  views 
  of 
  this 
  metaphase 
  are 
  shown 
  in 
  

   figs. 
  28 
  and 
  29, 
  and, 
  in 
  the 
  former, 
  a 
  single 
  chromosome 
  is 
  seen 
  passing 
  

   apparently 
  undivided 
  to 
  one 
  pole. 
  These 
  photo-micrographs 
  accord 
  with 
  

   Dr. 
  de 
  Winiwarter's 
  drawings 
  in 
  the 
  plate 
  of 
  his 
  paper. 
  This 
  paper 
  was 
  

   completed 
  in 
  March, 
  1914, 
  but 
  its 
  publication 
  has 
  been 
  delayed 
  until 
  this 
  year. 
  

  

  A 
  comparison 
  of 
  these 
  photo-micrographs 
  with 
  those 
  already 
  given 
  shows 
  

   that 
  the 
  total 
  volume 
  of 
  chromatin 
  on 
  the 
  spindles 
  of 
  Felis 
  is 
  much 
  smaller 
  

   than 
  that 
  seen 
  in 
  either 
  Stenobothrus 
  or 
  Triton, 
  and 
  the 
  same 
  result 
  is 
  

   obtained 
  from 
  comparison 
  of 
  the 
  chromosome 
  diameters. 
  But 
  Felis 
  is 
  a 
  

   mammal 
  and, 
  somatically, 
  is 
  the 
  most 
  highly 
  differentiated 
  animal 
  represented 
  

   in 
  this 
  Plate. 
  The 
  significance 
  of 
  this 
  evidence 
  has 
  been 
  recognised 
  by 
  

   Dr. 
  de 
  Winiwarter, 
  who 
  has 
  drawn 
  attention 
  to 
  it 
  in 
  his 
  paper. 
  

  

  Figs. 
  30 
  to 
  36 
  represent 
  the 
  bird, 
  Gallus 
  domesticus. 
  Fig. 
  30 
  shows 
  a 
  

   polar 
  view 
  of 
  the 
  primary 
  spermatocyte 
  metaphase. 
  Figs. 
  31 
  and 
  32 
  show 
  

   lateral 
  views 
  of 
  this 
  metaphase. 
  Figs. 
  33 
  and 
  34 
  show 
  polar 
  views 
  of 
  the 
  

   secondary 
  spermatocyte 
  metaphase 
  ; 
  and 
  lateral 
  views 
  are 
  shown 
  in 
  figs. 
  35 
  

   and 
  36. 
  These 
  photo-micrographs 
  clearly 
  prove 
  that 
  the 
  total 
  volume 
  of 
  

   chromatin 
  on 
  the 
  spindles 
  is 
  much 
  smaller 
  than 
  that 
  observed 
  in 
  the 
  

   corresponding 
  mitoses 
  of 
  Stenobothrus 
  and 
  Triton. 
  Unfortunately, 
  the 
  

   chromosomes 
  are 
  crowded 
  in 
  the 
  equatorial 
  plane 
  of 
  the 
  spindles, 
  and 
  

   cannot 
  be 
  measured 
  individually 
  ; 
  but 
  the 
  photo-micrographs 
  of 
  lateral 
  views 
  

   prove 
  that 
  the 
  chromosome 
  diameter 
  cannot 
  be 
  as 
  great 
  as 
  that 
  seen 
  in 
  

   Stenobothrus 
  and 
  Triton. 
  

  

  