314  The  Wolnirn  Pot-Culture  Experiments,  1903. 
iodide.  The  plant,  with  both  oxides,  gi-ew  fairly,  though  not 
equal  to  the  untreated,  and  did  not  die  away  as  it  did  with  the 
iodides. 
It  is  clear  from  this  that  the  iodides  of  the  two  metals 
manganese  and  lithium  have  an  injurious  effect  on  the  roots  of 
the  barley  plant,  this  being  more  marked  the  stronger  the 
solution  is.  Further,  the  oxides  do  not  have  this  harmful 
influence,  though  they  do  not  benefit  the  plant.  The  difference 
between  manganese  and  lithium  is  also  worthy  of  note,  the 
manganese  salts  producing  a thin,  long,  wiry  root,  the  lithium 
salts  a thick,  short,  and  stunted  one. 
Miscellaneous  Experiments. 
“ Head  " v.  “ Tail  ” Corn  for  Seed  Barley. 
Experiments  conducted  in  1901  and  1902  with  wheat’ 
indicated  that  there  was  no  advantage  to  be  gained  by  the 
selection  for  seed  purposes  of  the  larger  and  plumper  grains 
as  against  the  smaller  or  “ tail  ” corn.  Preliminary  trials  with 
barley,  made  at  the  Pot-culture  Station,  also  pointed  in  the 
same  direction,  and  it  was  decided,  therefore,  to  test  the 
question  more  thoroughly  in  1903.  In  a matter  of  this  kind 
it  is  necessary  to  distinguish  clearly  between  what  is  meant 
by  “head”  corn  and  what  by  “tail”  corn.  In  ordinary 
farming  “ head  ” corn  means  the  plump  grain  separated  from 
the  smaller  corns  and  from  all  weed  seeds,  &c.,  by  dressing 
the  grain  carefully ; while  the  “ tail  ” corn  is,  speaking 
genei’ally,  all  that  goes  through  the  screens,  and  inclmles  not 
only  the  small  corn,  but  broken  grains,  weed  seeds,  &c.  To 
sow  the  latter,  even  in  equal  quantity  by  weight,  in  competition 
with  large  plump  grain,  is  not  a fair  comparison,  for  the 
amount  of  really  good  seed  sown  is  less,  and  the  young  plant 
has,  moreover,  to  maintain  a struggle  with  the  weeds.  The 
true  comparison  should  be  between  seeds  capable  of  germina- 
tion, but  taking  in  the  one  case  the  large  grains  and  in  the 
other  the  small  grains.  This  was  done  in  the  present  instance, 
and  a better  description  of  the  experiment  would  pi’obably 
be  “‘large’  corn  v.  ‘small’  corn.”  The  sample  taken  was 
“ Standwell  ” barley,  the  “ large  ” corn  being  the  “ head  ” 
corn  as  obtained  direct  from  the  dressing  machine,  while  the 
“small”  corn  was  obtained  by  further  cleaning  of  the  “tail” 
corn,  using  finer  sieves  and  removing  the  weed  seeds  and 
rubbish  that  generally  accompany  the  “ offal  ” corn.  All 
broken  corns  were  similarly  removed  till  the  sample  was  one 
of  perfectly  sound,  though  “ small,”  corn.  Three  comparative 
trials  were  instituted  : — 
> Journal  ll.A.S.E,,  Vol.  G3,  1902,  pp.  353-356  ; and  Vol.  64,  1903, 
pp.  353,  354, 
