﻿SPEl{MATOGENi:,SJ.S 
  OF 
  PERIPI.ANETA 
  AMEKICANA. 
  571 
  

  

  On 
  the 
  Behaviour 
  of 
  the 
  Nucleolus 
  in 
  the 
  Sper- 
  

   matogenesis 
  of 
  Periplaneta 
  Americana. 
  

  

  By 
  

  

  J. 
  E. 
  S. 
  Moore, 
  A.R.C.S., 
  F.L.S., 
  

   and 
  

  

  L,. 
  E. 
  Robinson, 
  A.R.C.S., 
  

  

  from 
  the 
  Biological 
  Laboratory, 
  Royal 
  College 
  of 
  Science, 
  London. 
  

  

  With 
  Plates 
  44 
  and 
  45. 
  

  

  The 
  present 
  commuDication 
  lias 
  arisen 
  as 
  a 
  by-product 
  of 
  

   the 
  work 
  upon 
  the 
  reduction 
  processes 
  in 
  animals 
  and 
  plants, 
  

   upon 
  which 
  the 
  authors 
  have 
  for 
  some 
  time 
  past 
  been 
  

   engaged. 
  

  

  Only 
  a 
  few 
  cytologists 
  have 
  paid 
  particular 
  attention 
  to 
  

   the 
  nucleolus, 
  although 
  this 
  structure 
  appears 
  to 
  be 
  constantly 
  

   present 
  in 
  both 
  the 
  male 
  and 
  female 
  reproductive 
  cells. 
  

  

  The 
  great 
  majority 
  of 
  writers 
  on 
  the 
  subject 
  of 
  spermato- 
  

   geuesis 
  figure 
  the 
  nucleolus 
  in 
  their 
  drawings, 
  but 
  refrain 
  

   from 
  giving 
  any 
  definite 
  account 
  of 
  its 
  behaviour 
  throughout 
  

   the 
  whole 
  period 
  of 
  the 
  maturation 
  of 
  the 
  reproductive 
  

   cells. 
  

  

  In 
  recent 
  years, 
  however, 
  the 
  behaviour 
  of 
  this 
  body 
  has 
  

   arrested 
  the 
  attention 
  of 
  a 
  small 
  band 
  of 
  cytologists 
  on 
  

   account 
  of 
  the 
  part 
  it 
  may 
  possibly 
  play 
  in 
  some 
  of 
  the 
  

   hitherto 
  unexplained 
  functions 
  of 
  the 
  male 
  reproductive 
  

   element. 
  

  

  Henkiug 
  appears 
  to 
  have 
  been 
  the 
  first 
  investigator 
  to 
  

   describe 
  changes 
  in 
  the 
  nucleolus 
  of 
  the 
  reproductive 
  cell 
  in 
  

  

  