﻿138 
  Harper: 
  Inheritance 
  of 
  sugar 
  

  

  (*I4) 
  with 
  hooded 
  rats 
  reproducing 
  sexually 
  and 
  with 
  inbreeding, 
  

   by 
  Jennings 
  (*i6) 
  with 
  Difflugia 
  and 
  by 
  Hegner 
  ('19) 
  with 
  Arcella 
  

   reproducing 
  asexually 
  by 
  simple 
  cell 
  division. 
  Stout 
  ('15) 
  has 
  

   also 
  shown 
  that 
  such 
  series 
  can 
  be 
  produced 
  by 
  bud 
  variation 
  in 
  

   Coleus 
  and 
  that 
  by 
  selection 
  of 
  these 
  bud 
  variants 
  for 
  specific 
  leaf 
  

   patterns 
  races 
  of 
  purity 
  and 
  constancy 
  sufficient^ 
  for 
  successful 
  

   commercial 
  uses 
  can 
  be 
  produced. 
  The 
  facts 
  as 
  to 
  the 
  occurrence 
  

   of 
  widely 
  divergent 
  mutants 
  or 
  sports, 
  which 
  may 
  or 
  may 
  not 
  be 
  

   monstrosities, 
  and 
  their 
  fLx:ity 
  in 
  heredity 
  are 
  in 
  just 
  about 
  the 
  

   same 
  position 
  as 
  they 
  were 
  when 
  Darwin 
  concluded 
  that 
  such 
  

   sporadic 
  variations 
  have 
  probably 
  hot 
  played 
  any 
  very 
  significant 
  

   role 
  in 
  evolution. 
  The 
  discovery 
  that 
  such 
  forms 
  as 
  Oenothera 
  

   gigas 
  may 
  have 
  a 
  tetraploid 
  chromosome 
  number 
  is 
  highly 
  inter- 
  

   esting 
  and 
  may 
  indicate 
  a 
  possible 
  method 
  of 
  effective 
  evolutionary 
  

   change, 
  but 
  the 
  great 
  mass 
  of 
  what 
  have 
  been 
  more 
  recently 
  called 
  

   mutants 
  we 
  are 
  coming 
  to 
  realize 
  are 
  merely 
  the 
  extremes 
  of 
  

   series 
  of 
  fluctuating 
  variants. 
  There 
  is 
  adequate 
  evidence, 
  it 
  

   seems 
  to 
  me, 
  that 
  such 
  fluctuating 
  changes 
  may 
  involve 
  the 
  funda- 
  

   mental 
  constitution 
  of 
  the 
  cells 
  and 
  may 
  be 
  expressed 
  In 
  chromo- 
  

   some 
  changes 
  as 
  well 
  as 
  in 
  gross 
  characters. 
  The 
  discovery 
  that 
  

   forms 
  may 
  vary 
  by 
  a 
  single 
  chromosome 
  is 
  apparently 
  estabhshed 
  

   for 
  0. 
  lata. 
  Kuwada 
  ('11, 
  '15 
  and 
  '19) 
  has 
  claimed 
  also, 
  without 
  

   however 
  giving 
  very 
  adequate 
  evidence, 
  that 
  the 
  sugar 
  corns 
  vary 
  

   in 
  the 
  number 
  of 
  their 
  chromosomes 
  from 
  nine 
  to 
  twelve 
  (haploid 
  

   number) 
  and 
  that 
  the 
  sugar 
  corns 
  may 
  have 
  a 
  larger 
  number 
  of 
  

   chromosomes 
  than 
  the 
  starchy 
  corns. 
  Such 
  data 
  are 
  of 
  great 
  

   interest, 
  but 
  Kuwada's 
  figures 
  are 
  not 
  very 
  convincing 
  as 
  he 
  

   gives 
  no 
  full 
  series 
  of 
  the 
  stages 
  for 
  any 
  one 
  race. 
  He 
  lists 
  nine 
  

   varieties 
  with 
  which 
  he 
  worked. 
  Four 
  starchy 
  races 
  are 
  reported 
  

   as 
  showing 
  ten 
  chromosomes 
  (haploid 
  number), 
  one 
  sugar 
  corn 
  

   as 
  showing 
  nine 
  to 
  ten 
  and 
  nine 
  to 
  twelve, 
  respectively 
  (haploid 
  

   numbers) 
  • 
  In 
  his 
  1919 
  paper 
  he 
  attempts 
  to 
  utilize 
  these 
  obser- 
  

   vatlons 
  In 
  drawing 
  conclusions 
  as 
  to 
  the 
  hybrid 
  ancestry 
  of 
  corn- 
  

   As 
  I 
  pointed 
  out 
  ('12), 
  in 
  the 
  recent 
  genetical 
  studies 
  practically 
  

   the 
  first 
  advance 
  beyond 
  the 
  simple 
  concepts 
  that 
  every 
  visible 
  

   character 
  of 
  a 
  plant 
  is 
  due 
  to, 
  and 
  transmitted 
  by, 
  a 
  simple 
  fixed 
  

   factor 
  which 
  remains 
  unchanged, 
  except 
  for 
  certain 
  rather 
  rare 
  and 
  

   deep-seated 
  changes 
  resulting 
  in 
  mutations, 
  was 
  toward 
  a 
  theo- 
  

  

  