﻿AND 
  STARCH 
  CHARACTERS 
  IN 
  CORN 
  177 
  

  

  relative 
  effects 
  of 
  environment 
  and 
  heredity 
  on 
  the 
  form 
  of 
  the 
  

   kernels 
  and 
  the 
  degree 
  of 
  the 
  wrinkling. 
  Kernels 
  at 
  the 
  butt 
  of 
  

   the 
  ear 
  tend 
  to 
  be 
  smoother 
  as 
  a 
  result 
  of 
  extreme 
  pressure 
  from 
  

   the 
  husks 
  in 
  this 
  region. 
  The 
  kernels 
  at 
  the 
  tip 
  also 
  show 
  the 
  

   effects 
  of 
  exposure 
  if 
  the 
  husks 
  are 
  too 
  short 
  or 
  of 
  pressure 
  if 
  the 
  

   husks 
  are 
  long 
  and 
  heavy, 
  so 
  that 
  a 
  well 
  filled 
  ear 
  in 
  its 
  longitudinal 
  

   growth 
  meets 
  considerable 
  resistance 
  from 
  them. 
  The 
  hundreds 
  

   of 
  kernels 
  in 
  the 
  middle 
  region 
  of 
  the 
  ear 
  relatively 
  to 
  each 
  other 
  

   have 
  a 
  remarkably 
  constant 
  set 
  of 
  conditions 
  through 
  the 
  whole 
  

   of 
  their 
  development 
  and 
  the 
  variations 
  in 
  their 
  form 
  are 
  very 
  

   obviously 
  from 
  their 
  chance 
  distribution 
  to 
  be 
  interpreted 
  as 
  the 
  

   expression 
  of 
  the 
  exigencies 
  of 
  the 
  fusion 
  and 
  pairing 
  processes 
  of 
  

   fertilization, 
  plus 
  the 
  particular 
  and 
  general 
  qualities 
  of 
  the 
  gametes 
  

   which 
  fuse 
  and 
  the 
  chromosomes 
  which 
  pair. 
  It 
  has 
  been 
  too 
  

   commonly 
  assumed 
  that 
  the 
  variations 
  in 
  the 
  progeny 
  of 
  a 
  pure 
  

   race 
  or 
  the 
  progeny 
  from 
  the 
  crossing 
  of 
  tvv^o 
  pure 
  races 
  must 
  be 
  

   largely 
  if 
  not 
  wholly 
  due 
  to 
  the 
  external 
  environment. 
  With 
  our 
  

   increased 
  knowledge 
  of 
  the 
  complicated 
  processes 
  which 
  are 
  in- 
  

   volved 
  in 
  synapsis, 
  the 
  reduction 
  divisions, 
  gametic 
  cell 
  fusions 
  

   and 
  the 
  final 
  pairing 
  of 
  homologous 
  chromosomes 
  it 
  is 
  obvious 
  

   that 
  at 
  each 
  and 
  all 
  of 
  these 
  stages 
  there 
  are 
  abundant 
  opportun- 
  

   ities 
  for 
  variations 
  in 
  the 
  germ 
  plasm 
  arising 
  both 
  from 
  the 
  chem- 
  

   leal 
  and 
  physical 
  interactions 
  of 
  the 
  complex 
  and 
  labile 
  materials 
  

   of 
  the 
  chromosomes 
  upon 
  each 
  other 
  and 
  of 
  the 
  cytoplasm, 
  

   spindle 
  fibers, 
  etc., 
  upon 
  the 
  chromosomes. 
  As 
  a 
  single 
  illus- 
  

   tration 
  take 
  the 
  frequently 
  observed 
  and 
  figured 
  cases 
  of 
  the 
  

   occasional 
  chromosome 
  pairs 
  which 
  for 
  one 
  reason 
  or 
  another 
  

   remain 
  for 
  some 
  time 
  connected 
  in 
  the 
  equatorial 
  plate 
  and 
  are 
  

   tremendously 
  elongated 
  and 
  distorted 
  in 
  being 
  pulled 
  back 
  to 
  

   the 
  poles. 
  In 
  any 
  theory- 
  of 
  their 
  nature 
  and 
  structure 
  there 
  is 
  at 
  

   least 
  a 
  chance 
  that 
  such 
  a 
  pair 
  have 
  been 
  modified 
  in 
  some 
  way 
  

   and 
  are 
  diflferent 
  than 
  their 
  neighbors 
  either 
  before 
  or 
  as* 
  a 
  result 
  

   of 
  this 
  special 
  variation 
  from 
  the 
  nbrmal 
  processes 
  of 
  chromosome 
  

   separation. 
  Their 
  position 
  In 
  the 
  daughter 
  group 
  of 
  chromosomes 
  

   is 
  for 
  a 
  time 
  at 
  least 
  visibly 
  modified. 
  With 
  the 
  discovery 
  of 
  

   the 
  normal 
  paired 
  relation 
  of 
  the 
  homologous 
  chromosomes 
  of 
  

   diploid 
  nuclei 
  the 
  whole 
  matter 
  of 
  the 
  space 
  relations 
  of 
  the 
  

   chromosomes 
  with 
  reference 
  to 
  each 
  other, 
  to 
  the 
  centrosome 
  and 
  

  

  