﻿(ESTROUS 
  CYCLE 
  IN 
  TFIR 
  COMMON 
  FKRRET. 
  3o7 
  

  

  stage 
  of 
  the 
  pro-oestrnm 
  occurs 
  as 
  a 
  consequence 
  of 
  the 
  

   absence 
  of 
  a 
  fertilised 
  ovum, 
  for 
  which 
  the 
  uterus 
  was 
  pre- 
  

   pai-ing, 
  in 
  the 
  preceding 
  growth 
  stage. 
  For, 
  since 
  copulation 
  

   and 
  ovulation 
  can 
  only 
  take 
  place 
  during 
  oestrus, 
  the 
  uterine 
  

   denudation 
  occurs 
  prior 
  to 
  the 
  period 
  when 
  fertilisation 
  

   becomes 
  possible. 
  This 
  is 
  a 
  point 
  to 
  which 
  I 
  have 
  already 
  

   alluded. 
  

  

  The 
  view 
  that 
  the 
  pro-oestrum 
  is 
  an 
  act 
  of 
  preparation, 
  

   followed, 
  where 
  this 
  happens 
  to 
  be 
  useless, 
  by 
  a 
  destruction 
  

   of 
  the 
  preparation, 
  being 
  untenable, 
  I 
  am 
  led 
  to 
  the 
  conclu- 
  

   sion 
  that 
  this 
  process 
  is 
  the 
  result 
  of 
  a 
  " 
  wave 
  of 
  disturbance," 
  

   as 
  Mr. 
  Heape 
  expresses 
  it, 
  which 
  ushers 
  in 
  the 
  period 
  of 
  desire, 
  

   and 
  is 
  of 
  the 
  nature 
  of 
  a 
  consequence 
  rather 
  tlian 
  a 
  purpose. 
  

   On 
  the 
  other 
  hand 
  it 
  appears 
  to 
  me 
  not 
  altogether 
  improbable 
  

   that 
  the 
  renewal 
  of 
  the 
  mucosa 
  tissue 
  which 
  is 
  consequent 
  

   upon 
  the 
  degenerative 
  changes 
  may, 
  in 
  some 
  way, 
  help 
  to 
  

   prepare 
  the 
  uterus 
  for 
  the 
  attachment 
  of 
  the 
  ovum. 
  This 
  

   view 
  seems 
  to 
  have 
  been 
  entertained 
  by 
  Milnes 
  Marshall 
  

   (1893). 
  

  

  There 
  is 
  evidence, 
  however, 
  that 
  the 
  pro-oestrous 
  discharge 
  

   may 
  become 
  not 
  only 
  functionless 
  but 
  even 
  injurious, 
  as 
  in 
  

   the 
  more 
  severe 
  cases 
  of 
  menstruation 
  in 
  women. 
  This 
  is 
  in 
  

   accord 
  Avith 
  the 
  view 
  of 
  Metchnikoff 
  (1903) 
  that 
  the 
  condition 
  

   of 
  the 
  menstrual 
  tlow 
  in 
  the 
  human 
  subject 
  at 
  the 
  present 
  

   time 
  is 
  essentinlly 
  a 
  '' 
  disharmony 
  " 
  of 
  organisation, 
  and 
  is 
  

   probably 
  the 
  result 
  of 
  modifications 
  acquired 
  recently 
  in 
  the 
  

   history 
  of 
  the 
  race. 
  Mctchnikoff 
  refers 
  also 
  to 
  the 
  existence 
  

   of 
  similar 
  disharmonies 
  in 
  the 
  reproductive 
  apparatus 
  of 
  

   animals, 
  and 
  especially 
  of 
  animals 
  kept 
  in 
  captivity, 
  and 
  pro- 
  

   bably 
  the 
  severity 
  and 
  long 
  duration 
  of 
  the 
  ferret's 
  "heat" 
  

   period 
  would 
  be 
  regarded 
  by 
  this 
  author 
  as 
  a 
  further 
  example 
  

   of 
  the 
  occurrence 
  of 
  such 
  disharmonies. 
  

  

  SUMMAEY 
  AND 
  CONCLUDING 
  REMARKS. 
  

  

  The 
  female 
  ferret 
  is 
  monoestrous, 
  and 
  may 
  have 
  one, 
  two, 
  

   or 
  three 
  sexual 
  seasons 
  within 
  a 
  year; 
  but 
  although 
  the 
  

  

  