﻿CESTKOUS 
  CYCLE 
  IN 
  THE 
  COMMON 
  FERRET. 
  32o 
  

  

  time 
  she 
  is 
  refused 
  access 
  to 
  the 
  buck" 
  (Carnegie, 
  etc., 
  1902). 
  

   Several 
  of 
  my 
  ferrets 
  grew 
  unhealthy 
  and 
  died 
  during 
  the 
  

   sexual 
  season, 
  and 
  while 
  still 
  "on 
  heat," 
  and 
  I 
  am 
  disposed 
  

   to 
  believe 
  that 
  the 
  mortality 
  was 
  partly 
  due 
  to 
  their 
  being 
  

   refused 
  copulation. 
  

  

  The 
  period 
  of 
  oestrus 
  in 
  the 
  absence 
  of 
  the 
  male 
  I 
  have 
  

   found 
  to 
  be 
  extremely 
  prolonged. 
  In 
  one 
  individual 
  it 
  

   extended 
  for 
  six 
  weeks, 
  at 
  the 
  end 
  of 
  which 
  time 
  the 
  animal 
  

   was 
  killed, 
  the 
  uterus 
  being 
  found 
  to 
  be 
  in 
  a 
  condition 
  of 
  

   advanced 
  recuperation. 
  In 
  another 
  ferret, 
  however, 
  in 
  which 
  

   oestrus 
  was 
  observed 
  in 
  the 
  beginning 
  of 
  June 
  (at 
  the 
  time 
  

   when 
  it 
  was 
  procured), 
  the 
  period 
  of 
  " 
  heat" 
  was 
  completely 
  

   over 
  at 
  the 
  end 
  of 
  the 
  first 
  week 
  of 
  July, 
  coition 
  not 
  having 
  

   been 
  permitted. 
  Five 
  bitch 
  ferrets 
  which 
  I 
  obtained 
  in 
  the 
  

   month 
  of 
  October 
  lived 
  perfectly 
  healthily 
  during 
  an 
  anoestrous 
  

   period 
  which 
  extended 
  until 
  the 
  close 
  of 
  the 
  following 
  March, 
  

   when 
  they 
  began 
  to 
  s^how 
  signs 
  of 
  coming 
  "on 
  heat," 
  and 
  

   were 
  subsequently 
  killed 
  during 
  the 
  sexual 
  season. 
  

  

  It 
  appears 
  then, 
  that 
  the 
  ferret, 
  to 
  some 
  extent, 
  showed 
  a 
  

   transition 
  between 
  the 
  monoestrous 
  andpolyoestrous 
  condition, 
  

   since 
  in 
  those 
  individuals 
  which 
  experience 
  two 
  breeding 
  

   seasons 
  these 
  are 
  restricted 
  to 
  the 
  spring 
  and 
  summer; 
  so 
  

   that 
  it 
  must 
  be 
  a 
  matter 
  of 
  some 
  doubt 
  whether 
  the 
  time 
  

   between 
  the 
  two 
  "heat" 
  periods 
  should 
  be 
  correctly 
  described 
  

   as 
  a 
  ditEstrous 
  or 
  an 
  anoestrous 
  interval. 
  But, 
  as 
  already 
  

   indicated, 
  this 
  interval 
  is, 
  as 
  a 
  matter 
  of 
  fact, 
  generally, 
  or 
  

   perhaps 
  always, 
  occupied 
  partly 
  by 
  gestation. 
  

  

  A 
  number 
  of 
  interestino- 
  observations 
  bearing- 
  on 
  tliis 
  

   subject 
  have 
  been 
  made 
  by 
  Mr. 
  A. 
  H. 
  Cocks, 
  who 
  has 
  ke])t 
  

   severnl 
  members 
  of 
  the 
  family 
  Mastelid^ 
  in 
  activity. 
  A 
  

   female 
  otter 
  is 
  described 
  (Cocks, 
  1881) 
  as 
  coming 
  in 
  season 
  

   nearly 
  every 
  month 
  in 
  the 
  absence 
  of 
  the 
  male. 
  Upon 
  a 
  male 
  

   being 
  introduced, 
  copulation 
  was 
  observed 
  on 
  July 
  17th, 
  and 
  

   a 
  second 
  time 
  on 
  August 
  12th, 
  or 
  nearly 
  a 
  month 
  later. 
  

   Young 
  were 
  born 
  on 
  October 
  12th, 
  so 
  that 
  pregnancy 
  lasted 
  

   apparently 
  for 
  sixty-one 
  days. 
  From 
  these 
  observations 
  it 
  

   may 
  be 
  inferred 
  that 
  the 
  female 
  otter 
  is 
  polyoostrous 
  iu 
  the 
  

  

  VOL. 
  48, 
  PART 
  2. 
  NEW 
  SERIES. 
  23 
  

  

  