﻿(ESTROUS 
  CYCLE 
  IN 
  THE 
  COMMON 
  FERRET. 
  331 
  

  

  employed 
  in 
  describing 
  the 
  similar 
  plienomena 
  occurring 
  in 
  

   the 
  monkey 
  (Heape, 
  1894) 
  and 
  the 
  sheep 
  (Marshall^ 
  1903), 
  as 
  

   follows 
  ; 
  

  

  1. 
  Period 
  of 
  rest. 
  

  

  2. 
  Period 
  of 
  growth. 
  

  

  3. 
  Period 
  of 
  degeneration. 
  

  

  4. 
  Period 
  of 
  recuperation. 
  

  

  The 
  changes 
  taking 
  place 
  during 
  each 
  of 
  these 
  periods 
  

   occur 
  almost 
  simultaneously 
  throughout 
  the 
  whole 
  uterus. 
  

   Period 
  1 
  represents 
  the 
  anoestrum, 
  while 
  the 
  pro-oestrum 
  

   occurs 
  during 
  Periods 
  2 
  and 
  3. 
  CEstrus, 
  or 
  the 
  period 
  

   of 
  desire, 
  commences 
  at 
  the 
  close 
  of 
  the 
  period 
  of 
  degenera- 
  

   tion, 
  and, 
  as 
  already 
  mentioned, 
  may 
  extend 
  until 
  the 
  end 
  of 
  

   the 
  recuperation 
  stage, 
  or 
  perhaps 
  even 
  beyond 
  it. 
  Con- 
  

   sequently 
  there 
  may 
  be 
  no 
  metcestrum 
  with 
  the 
  ferret, 
  since 
  

   the 
  period 
  during 
  which 
  copulation 
  can 
  occur 
  is 
  liable 
  to 
  

   persist 
  until 
  the 
  uterus 
  has 
  reached 
  the 
  resting 
  stage. 
  

  

  1. 
  Period 
  of 
  Rest. 
  — 
  The 
  stroma, 
  of 
  which 
  the 
  greater 
  

   part 
  of 
  the 
  uterus 
  is 
  formed, 
  is 
  bounded 
  internally 
  by 
  an 
  

   epithelium 
  consisting 
  of 
  a 
  single 
  row 
  of 
  cubical 
  cells. 
  There 
  

   is 
  no 
  very 
  clear 
  line 
  of 
  demarcation 
  between 
  the 
  protoplasm 
  

   of 
  the 
  epithelial 
  cells 
  and 
  the 
  protoplasm 
  of 
  the 
  stroma, 
  

   neither 
  are 
  there 
  distinct 
  boundaries 
  between 
  the 
  individual 
  

   cells 
  of 
  the 
  stroma. 
  The 
  latter 
  tissue 
  is 
  fairly 
  uniform 
  in 
  

   character 
  throughout 
  both 
  the 
  body 
  of 
  the 
  uterus 
  and 
  the 
  

   two 
  cornua. 
  It 
  contains 
  numerous 
  glands, 
  bounded 
  by 
  

   epithelia 
  similar 
  to 
  that 
  lining 
  the 
  cavity. 
  Blood-vessels 
  of 
  

   small 
  size 
  are 
  also 
  present, 
  but 
  are 
  not 
  nearly 
  so 
  abundant 
  as 
  

   in 
  the 
  succeeding 
  giowtli 
  stage. 
  Some 
  of 
  these 
  are 
  shown 
  

   in 
  the 
  figure 
  (PI. 
  19, 
  fig. 
  1), 
  where 
  the 
  general 
  nature 
  of 
  the 
  

   uterine 
  stroma 
  during 
  the 
  resting 
  stage 
  is 
  indicated. 
  

  

  In 
  comparison 
  with 
  the 
  other 
  stages 
  of 
  the 
  cycle, 
  the 
  

   uterus 
  at 
  this 
  period 
  may 
  be 
  described 
  as 
  being 
  negatively 
  

   characterised. 
  

  

  The 
  general 
  shape 
  of 
  the 
  uterine 
  cavity, 
  as 
  it 
  appears 
  in 
  

   transverse 
  section, 
  is 
  shown 
  in 
  fig. 
  5 
  (PI. 
  20), 
  Avhich, 
  however, 
  

   represents 
  a 
  section 
  through 
  an 
  early 
  stage 
  of 
  the 
  growth 
  

  

  