﻿176 
  Harper: 
  Inheritance 
  of 
  sugar 
  

  

  colloidal 
  aggregates 
  as 
  the 
  gametes 
  and 
  the 
  chromosomes 
  when 
  

   brought 
  into 
  such 
  intricate 
  relations 
  as 
  are 
  the 
  elements 
  of 
  the 
  

   homologous 
  pairs 
  of 
  chromosomes 
  In 
  the 
  synaptic 
  knot 
  and 
  the 
  

   subsequent 
  pachyneme 
  spireme. 
  Speaking 
  in 
  terms 
  of 
  chemistry 
  

   and 
  molecules 
  no 
  chemist 
  would 
  expect 
  to 
  be 
  able 
  always 
  to 
  isolate 
  

   in 
  a 
  pure 
  state 
  by 
  physical 
  means 
  alone 
  such 
  complex 
  and 
  unstable 
  

   compounds 
  as 
  the 
  proteins 
  after 
  they 
  have 
  been 
  so 
  intimately 
  

   combined. 
  

  

  It 
  seems 
  to 
  me 
  necessary 
  here 
  to 
  keep 
  in 
  mind 
  always 
  in 
  con- 
  

   nection 
  with 
  our 
  theories 
  of 
  heredity 
  and 
  the 
  structure 
  of 
  the 
  germ 
  

   plasm 
  the 
  known 
  facts 
  as 
  to 
  such 
  polyphase 
  colloidal 
  systems 
  as 
  the 
  

   cells 
  appear 
  to 
  be. 
  That 
  the 
  homologous 
  chromosomes 
  do 
  pair, 
  

   combine 
  in 
  the 
  synaptic 
  knot, 
  separate 
  in 
  the 
  reduction 
  divisions, 
  

   live 
  a 
  longer 
  or 
  shorter 
  independent 
  existence 
  in 
  the 
  gametophytic 
  

   generations, 
  and 
  then 
  become 
  paired 
  again 
  sooner 
  or 
  later 
  as 
  a 
  

   result 
  of 
  gametic 
  fusion 
  are 
  facts 
  established 
  from 
  cytological 
  

   observations 
  and 
  confirmed 
  in 
  their 
  broad 
  outlines 
  by 
  the 
  evidence 
  

   from 
  breeding 
  experiments 
  for 
  segregation 
  and 
  chance 
  recombina- 
  

   tions 
  of 
  characters. 
  That 
  however 
  the 
  germ 
  plasms 
  remain 
  

   unaltered 
  through 
  these 
  reproductive 
  processes 
  is 
  not 
  shown 
  by 
  

   breeding 
  results 
  and 
  is 
  quite 
  inconsistent 
  with 
  what 
  we 
  should 
  

   expect 
  to 
  be 
  the 
  results 
  of 
  the 
  observed 
  cytological 
  processes 
  on 
  

   the 
  viscid 
  colloidal 
  materials 
  of 
  the 
  gametes 
  as 
  wholes 
  and 
  on 
  the 
  

   chromosomes 
  themselves. 
  

  

  ■ 
  F 
  

  

  As 
  noted 
  corn 
  with 
  its 
  large 
  number 
  of 
  individual 
  endosperms 
  

   showing 
  characters 
  easily 
  studied 
  which 
  can 
  be 
  obtained 
  simul- 
  

   taneously 
  and 
  in 
  parts 
  of 
  the 
  ear 
  under 
  practically 
  identical 
  en- 
  

   vironmental 
  conditions 
  though 
  each 
  is 
  the 
  product 
  of 
  a 
  distinct, 
  

   free, 
  and 
  chance-determined 
  pollination 
  (In 
  selfing 
  so 
  far 
  as 
  the 
  

   variations 
  in 
  pollen 
  of 
  the 
  same 
  individual 
  is 
  concerned, 
  in 
  open 
  

   pollination 
  so 
  far 
  as 
  variation 
  of 
  pollen 
  occurs 
  In 
  the 
  whole 
  field) 
  

   affords 
  very 
  special 
  advantages 
  for 
  the 
  study 
  of 
  variation 
  both 
  

   within 
  a 
  race 
  and 
  in 
  hybrids. 
  

  

  The 
  difficulty 
  in 
  distinguishing 
  between 
  variations 
  which 
  are 
  

   due 
  to 
  environment 
  and 
  those 
  which 
  are 
  germinal 
  and 
  congenital 
  

   largely 
  disappears 
  in 
  the 
  case 
  of 
  these 
  endosperm 
  characters. 
  

   Aside 
  from 
  the 
  peculiar 
  and 
  apparently 
  epigenetic 
  cases 
  of 
  the 
  

   pitted 
  and 
  chimaera-like 
  kernels, 
  it 
  Is 
  easy 
  to 
  distinguish 
  the 
  

  

  \ 
  

  

  