﻿HYBRIDISATION 
  IN 
  LEPIDOPTERA. 
  7 
  

  

  rather 
  to 
  difference 
  of 
  function 
  or 
  difference 
  of 
  habit 
  in 
  the 
  parent 
  

   species, 
  than 
  to 
  any 
  marked 
  difference 
  of 
  structure 
  in 
  the 
  genital 
  organs 
  

   brought 
  about 
  by 
  natural 
  selection 
  for 
  the 
  purpose 
  of 
  keeping 
  the 
  species 
  

   separate. 
  To 
  this 
  extent, 
  recent 
  experiment 
  supports 
  Darwin 
  that 
  

   sterility, 
  so 
  far 
  as 
  it 
  exists, 
  has 
  not 
  been 
  effected 
  through 
  natural 
  

   selection 
  ; 
  that 
  such 
  sterility 
  is, 
  however, 
  at 
  all 
  so 
  general 
  as 
  was 
  

   supposed 
  by 
  Darwin, 
  is, 
  as 
  already 
  noted, 
  much 
  open 
  to 
  question. 
  

   Experiments 
  on 
  hybridising 
  lepidoptera, 
  also, 
  tend 
  to 
  prove 
  that, 
  con- 
  

   trary 
  to 
  Darwin's 
  conclusion, 
  it 
  is 
  the 
  2 
  element 
  that 
  is 
  more 
  liable 
  

   to 
  be 
  affected 
  than 
  the 
  $ 
  , 
  many 
  $ 
  hybrids 
  being 
  functional 
  when 
  

   their 
  2 
  s 
  appear 
  to 
  be 
  absolutely 
  sterile. 
  

  

  The 
  difference 
  in 
  the 
  fertility 
  of 
  the 
  various 
  hybrids 
  that 
  have 
  been 
  

   reared 
  by 
  various 
  experiments, 
  e.g., 
  the 
  absolute 
  fertility 
  of 
  Anthrocera 
  

   hyhr.Jietcheri, 
  and 
  its 
  reciprocal 
  cross, 
  A. 
  hybr. 
  worthingi, 
  compared 
  with 
  

   the 
  absolute 
  sterility 
  of 
  Biston 
  hybr. 
  pilzii 
  and 
  its 
  reciprocal 
  B. 
  hybr. 
  

   Jiiinii 
  or 
  Smerinthus 
  hybr. 
  hybrid 
  us 
  and 
  its 
  reciprocal 
  S. 
  hybr. 
  inversa, 
  is 
  

   explained 
  by 
  Standfuss 
  as 
  being 
  due 
  to 
  the 
  varying 
  degrees 
  of 
  physio- 
  

   logical 
  divergence 
  between 
  the 
  parents 
  of 
  the 
  hybrid, 
  i.e., 
  that 
  the 
  

   different 
  pairs 
  of 
  species 
  are 
  related 
  to 
  each 
  other 
  in 
  very 
  varying 
  degrees. 
  

   Concerning 
  this 
  he 
  points 
  out 
  that, 
  beginning 
  with 
  pairs 
  of 
  species 
  

   with 
  which 
  crossings 
  may 
  be 
  effected, 
  without, 
  however, 
  the 
  capacity 
  

   of 
  producing 
  offspring, 
  and 
  with 
  such 
  degree 
  of 
  relationship 
  that 
  

   hybrid 
  offspring 
  could 
  be 
  obtained, 
  but 
  apparently 
  without 
  sufficient 
  

   vital 
  energy 
  to 
  maintain 
  life, 
  e.g., 
  Malacosoma 
  castrensis 
  x 
  franconica, 
  

   Satimiia 
  pavonia 
  x 
  isabellae, 
  there 
  existed 
  many 
  steps 
  to 
  a 
  higher 
  and 
  

   higher 
  physiological 
  affinity 
  between 
  the 
  various 
  pairs 
  of 
  species, 
  on 
  

   which 
  experiments 
  had 
  so 
  far 
  been 
  made, 
  until, 
  at 
  last, 
  although 
  not 
  

   to 
  a 
  very 
  high 
  degree, 
  hybrids 
  were 
  found 
  capable 
  of 
  reproduction, 
  

   e.g., 
  Drepana 
  hybr. 
  rebeli, 
  Glostera 
  hybr. 
  prima, 
  C. 
  hybr. 
  inversa. 
  In 
  

   other 
  cases, 
  the 
  $ 
  hybrid 
  has 
  been 
  found 
  capable 
  of 
  fertilising 
  a 
  

   female 
  of 
  one 
  or 
  other 
  of 
  the 
  parent 
  forms, 
  e.g., 
  Satimiia 
  bornemanni 
  

   S 
  X 
  pavonia 
  2 
  , 
  8. 
  emiliae 
  $ 
  x 
  pyri 
  2 
  , 
  G. 
  hybr. 
  raeschkei 
  $ 
  x 
  ana- 
  

   choreta 
  2 
  , 
  etc., 
  whilst, 
  in 
  still 
  rarer 
  cases, 
  the 
  2 
  hybrid 
  has 
  been 
  

   fertilised 
  by 
  a 
  male 
  of 
  one 
  or 
  other 
  of 
  the 
  parent 
  forms, 
  e.g., 
  Antheraea 
  

   pernxj- 
  yam 
  a 
  2 
  X 
  pernyi 
  $ 
  , 
  Saturnia 
  schaufussi 
  2 
  X 
  pavonia 
  $ 
  . 
  

   Beyond 
  this 
  stage 
  we 
  reach 
  the 
  few 
  cases 
  of 
  absolutely 
  fertile 
  hybrids 
  

   such 
  as 
  Anthrocera 
  hybr. 
  worthingi, 
  A. 
  hybr. 
  fletcheri, 
  Philosamia 
  hybr. 
  

   ivallacei, 
  Clostera 
  hybr. 
  prima, 
  Tephrosia 
  hybr. 
  ridingi 
  whose 
  ability 
  to 
  

   continue 
  their 
  own 
  kind 
  appears 
  in 
  confinement 
  only 
  bo 
  be 
  Limited, 
  as 
  

   in 
  the 
  case 
  of 
  pure 
  species, 
  to 
  the 
  exigencies 
  of 
  in-breeding 
  and 
  similar 
  

   adverse 
  circumstances. 
  Standfuss 
  concludes 
  from 
  his 
  experiments 
  

   that 
  "a 
  lengthy 
  period 
  of 
  existence, 
  phylogenetically 
  speaking, 
  of 
  the 
  

   divergence 
  between 
  nearly 
  related 
  types, 
  is 
  in 
  no 
  way 
  connected 
  with 
  

   the 
  higher 
  degree 
  of 
  difference 
  on 
  the 
  Lines 
  of 
  biological, 
  physiognomical 
  

   and 
  physiological 
  characters, 
  between 
  pairs 
  of 
  species 
  which 
  have 
  boon 
  

   divergent 
  for 
  a, 
  less 
  period 
  even 
  when 
  nearly 
  related 
  groups 
  of 
  species 
  

   are 
  in 
  question. 
  The 
  long 
  separated 
  Saturnia 
  pavonia 
  and 
  S. 
  spini 
  are, 
  

   in 
  most 
  of 
  their 
  characters, 
  less 
  separated 
  from 
  each 
  other 
  than 
  the 
  

   later 
  formed 
  S. 
  pyri 
  from 
  either 
  of 
  them." 
  

  

  The 
  comparative 
  impotence 
  of 
  2 
  hybrids 
  compared 
  with 
  # 
  hybrids 
  

   appears 
  to 
  be 
  largely 
  due, 
  as 
  already 
  noted, 
  to 
  gynandromorphism, 
  

   which 
  manifests 
  itself 
  Largelyin 
  the 
  intermixture 
  o\ 
  s 
  sexual 
  elements 
  

   among 
  the 
  more 
  or 
  less 
  normally 
  ov 
  abnormally 
  developed 
  ° 
  sexual 
  

  

  