﻿324 
  FEANOIS 
  H, 
  A. 
  MARSHALL. 
  

  

  ferrets" 
  and 
  white 
  ferrets 
  were 
  employed, 
  and 
  were 
  kept 
  

   under 
  constant 
  observation. 
  

  

  The 
  material 
  for 
  the 
  histological 
  part 
  of 
  the 
  work 
  was 
  

   generally 
  fixed 
  and 
  preserved 
  in 
  a 
  10 
  per 
  cent, 
  solution 
  of 
  

   formalin, 
  and 
  afterwards 
  treated 
  in 
  the 
  usual 
  way 
  for 
  section 
  

   cutting. 
  Sometimes 
  corrosive 
  sublimate 
  was 
  used 
  instead 
  of 
  

   formalin 
  as 
  a 
  fixing 
  agent. 
  The 
  stains 
  ordinarily 
  employed 
  

   were 
  a 
  combination 
  of 
  haematoxylin 
  and 
  eosin. 
  

  

  I 
  wish 
  to 
  record 
  my 
  obligations 
  to 
  Professor 
  Ewart 
  and 
  

   Professor 
  Schiifer 
  for 
  the 
  encouragement 
  and 
  assistance 
  which 
  

   they 
  have 
  rendered 
  me 
  in 
  furthering 
  my 
  researches. 
  To 
  Mr. 
  

   Heape, 
  also, 
  I 
  must 
  express 
  my 
  indebtedness 
  for 
  valuable 
  

   suggestions 
  on 
  a 
  subject 
  which 
  he 
  has 
  made 
  peculiarly 
  his 
  

   own. 
  Lastly, 
  I 
  take 
  this 
  further 
  opportunity 
  of 
  thanking 
  

   Sir 
  Thomas 
  Gibson 
  Carmichael, 
  Bart., 
  for 
  his 
  great 
  generosity 
  

   in 
  providing 
  an 
  endowment. 
  

  

  The 
  QEsteous 
  Cycle. 
  

  

  The 
  ferret 
  is 
  monoestrous, 
  the 
  female 
  usually 
  coming 
  in 
  

   season 
  at 
  the 
  end 
  of 
  March 
  or 
  beginning 
  of 
  April. 
  If 
  per- 
  

   mitted 
  to 
  become 
  pregnant 
  at 
  this 
  time 
  a 
  second 
  sexual 
  

   season 
  may 
  be 
  entered 
  upon 
  in 
  July, 
  while 
  occasionally 
  ferrets 
  

   have 
  been 
  known 
  to 
  breed 
  three 
  times 
  within 
  twelve 
  months 
  

   (Carnegie 
  and 
  other 
  authorities, 
  1901).^ 
  

  

  I 
  do 
  not 
  know 
  whether 
  the 
  female 
  ferret 
  ever 
  experiences 
  

   a 
  second 
  sexual 
  season 
  after 
  failing 
  to 
  become 
  pregnant 
  

   during 
  the 
  first 
  oestrus. 
  It 
  is 
  frequently 
  stated 
  by 
  fanciers 
  

   that 
  for 
  ferrets 
  to 
  live 
  healthily 
  ib 
  is 
  necessary 
  for 
  them 
  to 
  

   breed, 
  and 
  that 
  " 
  a 
  doe 
  ferret 
  will 
  sometimes 
  die 
  the 
  first 
  

  

  ^ 
  The 
  above 
  statements 
  are 
  based 
  upon 
  information 
  given 
  by 
  ferret 
  breeders 
  

   (cf. 
  Carnegie, 
  etc., 
  1902). 
  In 
  my 
  paper 
  on 
  the 
  "(Estrous 
  Cycle 
  in 
  the 
  Sheep" 
  

   (1903) 
  I 
  stated 
  that 
  the 
  ferret 
  was 
  monoestrous 
  and 
  had 
  a 
  single 
  sexual 
  season 
  

   annually. 
  This 
  conclusion, 
  which 
  is 
  only 
  sometimes 
  correct, 
  I 
  had 
  deduced 
  

   from 
  my 
  own 
  observations, 
  having 
  never 
  had 
  a 
  ferret 
  which 
  experienced 
  more 
  

   than 
  one 
  oestrous 
  cycle. 
  As 
  stated 
  in 
  the 
  text, 
  I 
  have 
  kept 
  ferrets 
  from 
  

   October 
  to 
  the 
  end 
  of 
  March, 
  during 
  which 
  time 
  they 
  showed 
  no 
  signs 
  of 
  

   coming 
  " 
  ou 
  heat." 
  A 
  ferret 
  fancier 
  assures 
  me 
  that 
  only 
  very 
  exceptionally 
  

   has 
  he 
  known 
  ferrets 
  come 
  in 
  season 
  between 
  August 
  and 
  February. 
  

  

  