The  Wohrirn  Pot-Culture  Experiments,  1903. 
Rainfall  at  Woburn  Experimental  Station,  1903. 
(292  feet  above  sea  level.) 
Inches 
Number  of 
days  on 
which  '01 
inch  or 
more  fell 
Inches 
Number  of 
days  on 
which  ‘01 
inch  or 
more  fell 
January 
2-44 
18 
July  . 
3-85 
15 
February 
•67 
7 
August 
3-46 
18 
March 
2-86 
18 
September  . 
2- 13 
16 
April  . 
1-43 
12 
October 
6-29 
26 
May  . 
3-23 
15 
November  . 
1-97 
14 
June  . 
4-98 
9 
December  . 
Total 
116 
34-47 
11 
179 
IT.  POT-CULTURE  EXPERIMENTS,  1903. 
The  Hills  Experiments. 
In  1902,  expei'imeiits  were  conducted  on  the  action  of  different 
compounds  of  manganese  on  the  growth  of  wheat  and  barley. 
The  oxitles,  chloride,  iodide,  carbonate,  sulphate,  phosphate, 
and  nitrate  of  manganese  were  severally  employed.  Results 
of  a somewhat  striking  nature  having  been  obtained  as  regards 
the  use  of  the  iodide  and  oxides,  it  was  determined  to  pursue 
the  inquiry  further  in  1903. 
The  iodide,  in  the  case  of  wheat,  retarded  germination  and 
gave  a much  reduced  crop,  some  of  the  plants  not  developing 
at  all.  Soaking  the  seed  in  a 10  per  cent,  solution  of  the  iodide 
produced  also  a very  harmful  effect,  which,  however,  was  not 
noticed  when  a b per  cent,  solution  was  used,  while  a 1 per 
cent,  solution  gave  a slight  increase  of  crop.  The  application 
of  the  black  oxide  of  manganese  (MnO^)  gave  a brown  colour 
to  the  surface  soil  and  caused  it  to  “cake.”  With  barley  the 
harmful  effects  of  the  iodide  were  not  shown,  whether  tliis 
was  applied  direct  to  the  soil  or  for  soaking  the  seed  ; the  black 
oxide,  as  with  wheat,  gave  the  black  colour  and  “caking”  of 
the  soil. 
1.  The  Injiuence  of  the  Iodides  and  Oxides  of  Manganese, 
Potassium,  Sodium,  and  Lithium  on  Wheat. 
The  seed  sown  was  grey-chaff  Browick  ; earthenware  pots 
were  used,  and  these  were  in  trijjlicate.  The  number  of 
seeds  sown  was  twelve  in  each  pot,  the  plants  being  subse- 
quently reduced  to  six  in  number.  In  previous  experiments 
the  salts  used,  when  soluble,  were  given  dissolved  in  water. 
To  meet  possible  objection  that  the  salts  were  removed  beyond 
the  reach  of  the  plant  in  the  early  stages,  the  applications  were 
this  time  made  by  mixing  the  salts  in  the  solid  state  with  the 
last  4 lb.  of  earth  used  in  tilling  the  pots.  The  seeds  sown 
