﻿496 
  J. 
  BRETLAND 
  FARMER 
  AND 
  J. 
  E. 
  S. 
  MOORE. 
  

  

  organisms 
  emphasise 
  the 
  importance 
  of 
  constituents, 
  

   rather 
  than 
  of 
  the 
  substance 
  regarded 
  as 
  a 
  whole. 
  

  

  Again, 
  the 
  interesting 
  results 
  obtained 
  by 
  Boveri 
  and 
  others 
  

   during 
  a 
  study 
  of 
  the 
  effects 
  of 
  polyspermy, 
  and 
  the 
  analysis 
  

   of 
  the 
  subsequent 
  behaviour 
  of 
  the 
  supernumerary 
  chromo- 
  

   somes 
  in 
  relation 
  to 
  abnormalities, 
  further 
  emphasise 
  the 
  

   individual 
  importance 
  of 
  each 
  of 
  these 
  structures, 
  and 
  tend 
  

   to 
  show 
  that 
  normal 
  organisation 
  depends, 
  inter 
  alia, 
  on 
  a 
  

   normal 
  grouping 
  of 
  chromosomes, 
  and 
  not 
  on 
  the 
  presence 
  

   of 
  a 
  mere 
  normal 
  amount 
  of 
  chromosomic 
  substance. 
  

  

  Furthermore, 
  a 
  considerable 
  weight 
  of 
  evidence 
  has 
  accu- 
  

   mulated 
  within 
  recent 
  years 
  that 
  renders 
  it 
  difficult 
  to 
  dis- 
  

   sociate 
  the 
  facts 
  of 
  heredity 
  from 
  an 
  admission 
  of 
  the 
  

   existence 
  of 
  discrete 
  particles 
  that 
  are, 
  individually 
  or 
  collec- 
  

   tively, 
  responsible 
  for 
  the 
  appearance 
  of 
  those 
  particular 
  traits 
  

   that 
  characterise 
  one 
  organism 
  and 
  separate 
  it 
  from 
  others. 
  

   Investigations 
  on 
  the 
  behaviour 
  of 
  hybrids 
  militate 
  strongly 
  

   against 
  the 
  assumption 
  that 
  during 
  fertilisation 
  any 
  real 
  

   fusion 
  of 
  the 
  parental 
  substances 
  responsible 
  for 
  the 
  expres- 
  

   sion 
  of 
  particular 
  features 
  occurs. 
  

  

  To 
  avoid 
  possible 
  misconception, 
  however, 
  we 
  may 
  as 
  well 
  

   state 
  expressly 
  that 
  in 
  thus 
  formulating 
  the 
  problem 
  as 
  it 
  

   presents 
  itself 
  to 
  our 
  own 
  minds, 
  we 
  are 
  far 
  from 
  supposing 
  

   that 
  the 
  " 
  hereditary 
  substance 
  " 
  may 
  not 
  operate 
  cor- 
  

   relativel}^, 
  so 
  as 
  to 
  become 
  responsible 
  for 
  the 
  production 
  of 
  

   groups 
  of 
  characters. 
  But 
  admitting 
  that 
  the 
  chromosomes 
  

   really 
  possess 
  the 
  sort 
  of 
  importance 
  usually 
  assigned 
  (on 
  

   good 
  grounds, 
  as 
  we 
  think) 
  to 
  them, 
  Ave 
  fail 
  to 
  understand 
  

   how 
  a 
  mixture, 
  amounting 
  really 
  to 
  complete 
  fusion, 
  of 
  such 
  

   hereditary 
  substances 
  can 
  produce 
  the 
  observed 
  appearances. 
  

   How, 
  for 
  example, 
  could 
  one 
  account 
  for 
  the 
  segregation 
  of 
  

   ancestral 
  characters 
  in 
  inter-breeding 
  hybrids, 
  if 
  the 
  indi- 
  

   viduality 
  of 
  the 
  original 
  chromosomes 
  becomes 
  really 
  obliter- 
  

   ated 
  during 
  each 
  generation 
  ? 
  But, 
  on 
  the 
  other 
  hand, 
  as 
  

   Weismaun 
  long 
  ago 
  pointed 
  out, 
  it 
  is 
  impossible 
  to 
  continue 
  

   indefinitely 
  to 
  accumulate 
  the 
  primordia 
  (anlageu) 
  of 
  cha- 
  

   racters, 
  as 
  they 
  are 
  doubled 
  at 
  each 
  act 
  of 
  fertilisation. 
  

  

  