﻿THR 
  MAIOTIC 
  PHASE 
  IN 
  ANIMALS 
  AND 
  PLANTS. 
  529 
  

  

  continued 
  multiplication 
  of 
  the 
  elements 
  which, 
  in 
  the 
  first 
  

   instance, 
  constituted 
  the 
  so-called 
  generative 
  blastema 
  of 
  the 
  

   embryo. 
  

  

  In 
  the 
  adult 
  male, 
  the 
  cells 
  which 
  are 
  about 
  to 
  become 
  

   sexually 
  mature 
  are 
  found 
  to 
  be 
  still 
  multiplying- 
  through 
  the 
  

   continuation 
  of 
  the 
  same 
  series 
  of 
  pre-maiotic 
  divisions 
  

   whereby 
  they 
  have 
  been 
  increased 
  from 
  the 
  segmentation 
  of 
  

   the 
  ovum 
  onwards, 
  and 
  as 
  this 
  pre-maiotic 
  multiplication 
  

   differs 
  only 
  in 
  certain 
  details 
  from 
  the 
  processes 
  already 
  

   described 
  so 
  fully 
  in 
  numerous 
  treatises 
  upon 
  cell 
  division 
  in 
  

   general, 
  it 
  will 
  only 
  be 
  necessary 
  here 
  to 
  briefly 
  recount 
  the 
  

   successive 
  stages 
  of 
  the 
  process, 
  so 
  that 
  the 
  history 
  may 
  

   appear 
  complete 
  aiid 
  the 
  special 
  peculiarities 
  of 
  the 
  somatic 
  

   cell 
  division 
  in 
  the 
  cockroach 
  may 
  be 
  brought 
  into 
  sufficient 
  

   prominence. 
  

  

  In 
  the 
  example 
  we 
  have 
  chosen 
  the 
  cells 
  of 
  the 
  pre-maiotic 
  

   series 
  which 
  are 
  about 
  to 
  divide, 
  whether 
  they 
  are 
  encoun- 
  

   tered 
  within 
  the 
  sexual 
  glands 
  or 
  elsewhere 
  in 
  the 
  tissues 
  of 
  

   the 
  body, 
  present 
  the 
  rather 
  characteristic 
  appearance 
  repre- 
  

   sented 
  in 
  fig. 
  40, 
  a 
  very 
  irregular 
  network 
  of 
  chromatin 
  

   and 
  linin 
  being 
  grouped 
  within 
  the 
  nuclear 
  membrane 
  round 
  

   one 
  or 
  two 
  highly 
  chromatic 
  nucleoli. 
  Among 
  such 
  elements 
  

   mitosis 
  is 
  ushered 
  in 
  by 
  the 
  increasingly 
  chromatic 
  appear- 
  

   ance 
  of 
  the 
  cells, 
  this 
  being 
  followed 
  by 
  the 
  gradual 
  evolution 
  

   of 
  a 
  definite 
  arrangement 
  of 
  the 
  chromatin, 
  and 
  in 
  the 
  

   particular 
  type 
  under 
  consideration 
  the 
  latter 
  process 
  is 
  not 
  

   by 
  any 
  means 
  without 
  interest 
  from 
  a 
  general 
  point 
  of 
  view. 
  

  

  At 
  first 
  the 
  cells 
  which 
  are 
  preparing 
  for 
  division 
  present 
  

   an 
  almost 
  even 
  granulation 
  of 
  the 
  chromatin 
  within 
  their 
  

   nuclei, 
  and 
  this 
  in 
  its 
  consistency 
  strongly 
  suggests 
  a 
  foam 
  

   structure 
  of 
  the 
  ordinary 
  type; 
  but 
  after 
  a 
  time 
  the 
  ''chro- 
  

   matic 
  confusion," 
  as 
  it 
  were, 
  sorts 
  itself 
  out 
  into 
  obvious 
  

   condensations 
  or 
  cloudy 
  areas, 
  and 
  it 
  is 
  apparently 
  unques- 
  

   tionable 
  that 
  each 
  of 
  these 
  primitive 
  chromatic 
  clouds 
  is 
  

   individually 
  the 
  forerunner 
  of 
  one 
  of 
  the 
  future 
  chromosomes 
  

   (figs. 
  41-44). 
  

  

  The 
  gradual 
  condensation 
  which 
  occurs 
  in 
  each 
  such 
  cloud 
  

  

  