Their  Application  to  Stock-hr ceding. 
343 
wheat  absolutely  indistinguishable  from  the  parent  has  been 
picked  out  of  the  progeny  of  the  cross-bred  and  grown  on  for 
two  seasons  without  showing  any  signs  of  “ reversion.”  Such 
a fact  is  so  markedly  at  variance  with  what  one  hears  of  the 
experience  of  breeders  of  pedigree  stock  that  it  may  be  worth 
stating  in  another  form.  Thus,  among  the  progeny  of  two 
cross-bred  Shorthorn  x Aberdeen  Angus,  pure  Shorthorn  and 
pure  Aberdeen  Angus  individuals  would  occur,  ^ and  further, 
they  would  stand  the  test  of  being  bred  from,  for  if  crossed 
with  the  pure  type  of  Shorthorn  or  Aberdeen  Angus  respec- 
tively only  the  pure  types  would  result.  To  the  breeder  of 
pedigree  stock  the  question  at  once  arises,  “ Should  such 
animals  find  a place  in  the  herd-books  ? ” The  value  of 
pedigree  as  we  see  it  now  lies  in  the  fact  that  the  gametes 
(ova  and  spermatozoa  in  this  case)  of  the  individuals  of  any 
particular  strain  are  all  of  the  same  type.  That  now  is  the 
sole  test  of  the  purity  of  a strain,  and  as  far  as  gametic  purity 
goes  such  animals  are  indistinguishable  from  those  of  the  most 
carefully  bred  herds  in  the  woi’ld.  Yet  their  grandparents 
were  Shorthorn  and  Aberdeen  Angus. 
Turning  now  to  barleys,  we  find  again  that  the  laws 
enunciated  by  Mendel  hold  with  the  same  accuracy.  It  would 
serve  no  useful  purpose  here  to  describe  the  investigations  so 
far  made  in  any  detail.  I must  content  myself  with  grouping 
some  of  the  more  important  charactei’S  into  dominants  and 
corresponding  recessives,  as  a knowledge  of  this  will  enable 
any  one  to  foretell  with  reasonable  certainty  the  results  of  any 
particular  cross  between  races  showing  these  characters. 
Domimuit. 
Two  row  ..... 
Abyssinian  types  .... 
Lax  ...... 
Awnless  ...... 
Hooded  (i.e.  with  trifurcate  pale.v) 
Dark  coloured  (black  or  purple,  &c.) 
Adherent  palea;  .... 
Jifcessire. 
Six  row. 
Two  row. 
Dense. 
Awned. 
.\wned. 
Light  coloured. 
Naked  grain. 
So  far,  though,  we  have  only  dealt  with  characters  which  are 
either  dominant  or  recessive — characters  similar  to  those  found 
by  Mendel  in  his  original  work  with  peas.  There  are,  however, 
a considerable  number  of  pairs  of  characters  which  on  crossing 
do  not  show  any  clear  dominance  or  recessiveness ; and  it  is 
important  to  realise  that  tliis  particular  phenomenon — probably 
a very  common  one — in  no  way  interferes  with  the  fundamental 
fact  that  the  gametes  are  pure  with  respect  to  the  characters 
they  carry.  Such  a character  as  the  grey  colour  of  the  chaff  of 
Rivet  wheat  may  be  well  marked  in  a cross-bred  with  a white 
' I say  nothing  of  the  other  types  appearing  in  this  generation.  The  story 
promises  to  be  a complex  one. 
