﻿194 
  Prof. 
  W. 
  Bateson 
  and 
  Miss 
  C. 
  Pellew. 
  The 
  Genetics 
  of 
  

  

  Discussion. 
  

  

  Features 
  somewhat 
  comparable 
  with 
  the 
  first 
  two 
  of 
  these 
  peculiarities 
  

   have 
  been 
  recorded, 
  but 
  the 
  third 
  is, 
  so 
  far 
  as 
  we 
  are 
  aware, 
  as 
  yet 
  without 
  

   parallel. 
  Biffen* 
  has 
  observed 
  the 
  total 
  " 
  suppression 
  " 
  of 
  a 
  character, 
  grey 
  

   chaff, 
  introduced 
  by 
  Kivet 
  wheat, 
  in 
  a 
  cross 
  with 
  Polish 
  ; 
  and, 
  in 
  variegated 
  

   Capsicum, 
  crossed 
  with 
  green, 
  Ikenof 
  never 
  recovered 
  the 
  green 
  in 
  later 
  

   generations. 
  BaurJ 
  interpreted 
  certain 
  wholly 
  white 
  and 
  wholly 
  green 
  off- 
  

   spring 
  obtained 
  in 
  crosses 
  between 
  white-skinned 
  and 
  green 
  plants 
  by 
  the 
  

   very 
  probable 
  suggestion 
  that 
  the 
  green 
  or 
  white 
  characters 
  might 
  have 
  

   been 
  omitted 
  by 
  somatic 
  segregation, 
  though 
  the 
  inference 
  was 
  scarcely 
  

   capable 
  of 
  direct 
  proof. 
  Winge§ 
  also 
  saw 
  something 
  possibly 
  analogous 
  in 
  

   Humulus, 
  traces 
  of 
  variegation 
  appearing 
  in 
  lower 
  leaves 
  of 
  plants, 
  which 
  

   subsequently 
  became 
  green. 
  None 
  of 
  these 
  examples, 
  however, 
  are 
  strictly 
  

   comparable, 
  but 
  Winge's 
  case 
  perhaps 
  comes 
  nearest. 
  

  

  A 
  gradational 
  change 
  in 
  the 
  numerical 
  proportions 
  of 
  the 
  gametes 
  at 
  the 
  

   successive 
  nodes 
  has 
  not, 
  we 
  believe, 
  been 
  elsewhere 
  observed. 
  The 
  dis- 
  

   tribution 
  of 
  the 
  type 
  gametes 
  borne 
  by 
  the 
  pointed 
  intermediates 
  corresponds, 
  

   no 
  doubt, 
  in 
  a 
  loose 
  way 
  with 
  the 
  distribution 
  of 
  vegetative 
  vigour. 
  But 
  

   weak 
  growth 
  on 
  type 
  plants 
  is 
  not 
  specially 
  likely 
  to 
  bear 
  rogues, 
  nor 
  do 
  

   rogues, 
  however 
  luxuriantly 
  growing, 
  produce 
  types. 
  Aetiological 
  interpreta- 
  

   tions 
  of 
  this 
  kind 
  are 
  inconsistent 
  with 
  all 
  that 
  we 
  have 
  learnt 
  of 
  genetic 
  

   principle. 
  Nevertheless, 
  the 
  coincidence 
  may 
  not 
  be 
  without 
  significance. 
  

  

  Where 
  the 
  output 
  of 
  the 
  several 
  sorts 
  of 
  gametes 
  is 
  so 
  uncertain 
  no 
  gametic 
  

   system 
  of 
  a 
  Mendelian 
  kind 
  can 
  be 
  propounded. 
  The 
  most 
  that 
  can 
  be 
  

   expected 
  of 
  such 
  a 
  system 
  in 
  this 
  case 
  is 
  that 
  it 
  should 
  qualitatively 
  represent 
  

   the 
  distinction 
  between 
  the 
  genetic 
  nature 
  of 
  the 
  classes 
  here 
  called 
  2 
  and 
  3. 
  

   Since 
  type 
  (T) 
  and 
  rogue 
  (R) 
  gives 
  Fi 
  rogue, 
  neither 
  of 
  these 
  intermediates 
  can 
  

   receive 
  a 
  rogue 
  gamete 
  in 
  fertilization. 
  Since 
  also 
  these 
  two 
  classes 
  differ 
  

   from 
  the 
  type, 
  the 
  gametes 
  composing 
  either 
  of 
  them 
  cannot 
  both 
  be 
  type- 
  

   bearing. 
  From 
  this 
  reasoning 
  it 
  appears 
  to 
  be 
  practically 
  certain 
  that 
  two 
  

   sorts 
  of 
  intermediate 
  gametes 
  must 
  exist, 
  the 
  one 
  more 
  type-like, 
  T', 
  the 
  other 
  

   more 
  rogue-like, 
  R'. 
  TT' 
  will 
  then 
  represent 
  Class 
  2 
  and 
  TR' 
  Class 
  3 
  ; 
  but 
  

   where, 
  as 
  in 
  this 
  case, 
  there 
  is 
  no 
  clear 
  discontinuity 
  no 
  analysis 
  can 
  be 
  pressed. 
  

   All 
  that 
  can 
  be 
  positively 
  stated 
  is 
  that 
  there 
  are 
  two 
  sorts 
  of 
  intermediate 
  

   gametes, 
  that 
  both 
  are 
  unstable, 
  being 
  incapable 
  of 
  constituting 
  a 
  stable 
  zygote, 
  

  

  * 
  1 
  Jour. 
  Genetics,' 
  vol. 
  5, 
  p. 
  227 
  (1916). 
  

   t 
  Ibid., 
  vol. 
  6, 
  p. 
  201 
  (1917). 
  

  

  X 
  Especially 
  ' 
  Zeits. 
  f. 
  ind. 
  Abstammungslehre,' 
  vol. 
  4, 
  Heft 
  2 
  (1910). 
  

   § 
  'C. 
  R. 
  Lab. 
  Carlsberg,' 
  vol. 
  14, 
  No. 
  3, 
  p. 
  11 
  (1919). 
  

  

  