﻿338 
  FRANCIS 
  H. 
  A. 
  MARSHALL. 
  

  

  oesbrous 
  cycle 
  may 
  recur 
  the 
  "heat" 
  periods 
  are 
  usually 
  

   restricted 
  to 
  the 
  spring- 
  and 
  summer 
  months, 
  the 
  autumn 
  and 
  

   winter 
  being 
  occupied 
  by 
  a 
  prolonged 
  anoestrum. 
  In 
  showing 
  

   this 
  tendency 
  towards 
  a 
  coucentration 
  of 
  sexual 
  seasons 
  the 
  

   ferret 
  approaches 
  the 
  polyoestrous 
  condition, 
  being 
  in 
  fact, 
  in 
  

   this 
  respect, 
  intermediate 
  between 
  the 
  dog 
  or 
  cat, 
  which 
  have 
  

   two, 
  or 
  occasionally 
  three, 
  fairly 
  regularly 
  recurrent 
  oestrous 
  

   cycles, 
  and 
  the 
  otter, 
  which, 
  in 
  captivity 
  at 
  any 
  rate, 
  has 
  

   been 
  shown 
  to 
  be 
  polyoestrous 
  with 
  a 
  series 
  of 
  dioestrous 
  

   cycles, 
  each 
  of 
  a 
  month's 
  duration, 
  occasionally 
  interrupted 
  

   by 
  a 
  longer 
  anoestrous 
  period. 
  

  

  The 
  pro-oestrum 
  with 
  the 
  ferret 
  may 
  extend 
  for 
  three 
  

   weeks, 
  while 
  the 
  oestrus, 
  in 
  the 
  absence 
  of 
  the 
  male, 
  may 
  last 
  

   for 
  another 
  six 
  weeks, 
  or 
  even 
  longer. 
  

  

  The 
  changes 
  which 
  occur 
  in 
  the 
  non-pregnant 
  uterus 
  during- 
  

   the 
  oestrous 
  cycle 
  may 
  be 
  divided 
  according 
  to 
  four 
  periods 
  

   as 
  follows 
  : 
  

  

  (1) 
  Period 
  of 
  rest. 
  

  

  (2) 
  Period 
  of 
  growth. 
  

  

  (3) 
  Period 
  of 
  degeneration. 
  

  

  (4) 
  Period 
  of 
  recuperation. 
  

  

  The 
  first 
  period 
  corresponds 
  to 
  the 
  anoe-trura 
  during 
  which 
  

   the 
  uterus 
  is 
  in 
  the 
  normal 
  state. 
  This 
  is 
  followed 
  b}' 
  the 
  

   growth 
  period 
  during 
  which 
  the 
  uterine 
  cavity 
  becomes 
  

   reduced 
  to 
  about 
  half 
  its 
  usual 
  size, 
  while 
  the 
  mucosa 
  is 
  

   correspondingly 
  thickened. 
  Meanwhile 
  the 
  blood-vessels 
  

   become 
  much 
  congested 
  and 
  subsequently 
  break 
  down, 
  thus 
  

   marking- 
  the 
  commencement 
  of 
  the 
  period 
  of 
  degeuei-ation. 
  

   The 
  blood-corpuscles 
  become 
  scattered 
  in 
  considerable 
  

   numbers 
  in 
  the 
  stroma, 
  and 
  eventually 
  in 
  the 
  uterine 
  cavity 
  

   also, 
  owing 
  to 
  the 
  removal 
  in 
  many 
  places 
  of 
  the 
  lining 
  epi- 
  

   thelium. 
  In 
  one 
  specimen 
  I 
  found 
  evidence 
  also 
  of 
  a 
  pro- 
  

   oestrous 
  denudation 
  of 
  the 
  underlying 
  stroma 
  tissue. 
  CEstrus 
  

   probably 
  commences 
  towards 
  the 
  close 
  of 
  the 
  period 
  of 
  

   degeneration, 
  and 
  continues 
  throughout 
  the 
  recuperation 
  

   stage, 
  or 
  perhaps 
  even 
  beyond 
  it. 
  During 
  the 
  latter 
  period 
  

   the 
  uterus 
  recovers 
  its 
  normal 
  condition, 
  though 
  the 
  cavity 
  is 
  

  

  