﻿(ESTROUS 
  CYCLE 
  IN 
  THE 
  COMMON 
  FERRET. 
  329 
  

  

  and 
  perliaps 
  longer. 
  The 
  animal 
  had 
  copulated 
  on 
  the 
  day 
  

   on 
  which 
  it 
  was 
  killed, 
  but 
  not 
  previously 
  during 
  that 
  oestrus. 
  

   The 
  ovum 
  is 
  seen 
  to 
  be 
  much 
  shrunken 
  and 
  obviously 
  

   degenerate, 
  while 
  it 
  is 
  no 
  longer 
  surrounded 
  by 
  a 
  discus 
  

   proligerus. 
  The 
  membrana 
  granulosa 
  has 
  almost 
  completely 
  

   disappeared, 
  but 
  a 
  few 
  cells 
  in 
  an 
  advanced 
  state 
  of 
  degenera- 
  

   tion 
  remain 
  scattered 
  in 
  the 
  cavity. 
  There 
  is 
  the 
  beginning 
  

   of 
  a 
  loose 
  ingrowth 
  of 
  connective 
  tissue, 
  but 
  this, 
  at 
  the 
  stage 
  

   nnder 
  consideration, 
  is 
  very 
  slight. 
  The 
  connective-tissue 
  

   wall 
  of 
  the 
  follicle 
  presents 
  the 
  appearance 
  of 
  being 
  composed 
  

   of 
  very 
  irregular!}^ 
  ai-ranged 
  strands, 
  the 
  distinction 
  between 
  

   theca 
  externa 
  and 
  tlieca 
  interna 
  having 
  become 
  obliterated, 
  

   while 
  there 
  is 
  no 
  distinct 
  line 
  of 
  separation 
  from 
  the 
  outlying- 
  

   ovarian 
  stroma. 
  

  

  The 
  Formation 
  of 
  the 
  Corpus 
  Luteum. 
  — 
  I 
  made 
  no 
  

   attempt 
  to 
  obtain 
  a 
  series 
  of 
  stages 
  illustrating 
  the 
  develop- 
  

   ment 
  of 
  the 
  corpus 
  luteum 
  in 
  the 
  ferret. 
  Such 
  few 
  examples 
  

   as 
  I 
  have 
  examined 
  show 
  the 
  usual 
  ingrowth 
  among 
  the 
  

   lutein 
  cells 
  of 
  connective 
  tissue 
  from 
  the 
  follicle's 
  wall; 
  and, 
  

   although, 
  taken 
  by 
  themselves, 
  they 
  do 
  not 
  prove 
  that 
  the 
  

   lutein 
  cells 
  are 
  derived 
  from 
  the 
  membrana 
  granulosa, 
  they 
  

   are, 
  in 
  a 
  general 
  way, 
  confirmatory 
  of 
  the 
  description 
  given 
  

   elsewhere 
  of 
  the 
  origin 
  of 
  the 
  corpus 
  luteum 
  in 
  the 
  mouse, 
  

   the 
  rabbit, 
  and 
  the 
  sheep, 
  there 
  being 
  distinct 
  evidence 
  of 
  

   the 
  interepithelial 
  nature 
  of 
  the 
  ingrowth. 
  I 
  have 
  also 
  

   lately 
  obtained 
  sections 
  through 
  a 
  young 
  corpus 
  luteum 
  of 
  a 
  

   cat 
  which, 
  at 
  the 
  time 
  of 
  killing, 
  was 
  "on 
  heat," 
  or 
  had 
  been 
  

   very 
  shortly 
  before; 
  and 
  these 
  sections 
  show 
  the 
  same 
  point. 
  

  

  Since 
  the 
  publication 
  of 
  my 
  account 
  a 
  paper 
  by 
  Colin 
  

   (1903) 
  describing 
  an 
  experimental 
  investigation 
  on 
  the 
  mode 
  

   of 
  formation 
  of 
  the 
  corpus 
  luteum 
  in 
  the 
  rabbit 
  has 
  appeared, 
  

   and 
  the 
  result 
  of 
  this 
  investigation 
  has 
  been 
  to 
  further 
  

   confirm 
  the 
  view 
  that 
  the 
  lutein 
  cells 
  are 
  formed 
  from 
  the 
  

   follicular 
  epithelium. 
  Cohn 
  obtained 
  a 
  series 
  of 
  stages, 
  the 
  

   animals 
  being 
  killed 
  at 
  stated 
  intervals 
  after 
  coition. 
  

  

  A 
  similar 
  conclusion 
  has 
  been 
  arrived 
  at 
  by 
  Sandes, 
  who 
  

   describes 
  the 
  process 
  of 
  formation 
  of 
  the 
  corpus 
  luteum 
  of 
  

  

  