790 
Journal of Agricultural Research 
Vol. XXIV, No. 9 
that even the trace found in the acid extraction would not be available 
to the plants growing in a Knop’s solution. 
Twelve Alaska pea seedlings were placed in each of four jars containing 
a Knop’s solution. At the beginning of the experiment i part of man¬ 
ganese in the form of the sulphate to 1,000,000 parts of the solution was 
added to each of two of the pots. After the plants had been growing 
three or four weeks the concentration of manganese was increased to five 
parts per million of the Knop’s solution. One cubic centimeter of a man¬ 
ganese-free ferric chlorid solution which contained 0.001 gm. iron was 
added to each of the pots at the time the solutions were changed. 
During the first four or six weeks of growth there was little or no differ¬ 
ence in the size or appearance of the plants. Therefore the plants w'hich 
received no manganese except that contained in the seed began to show 
effects which can not be accounted for in any other way except for a 
lack of this element. The first effect to be observed was that the young 
buds as they unfolded were yellowish instead of a normal green color 
and later became flecked with small specks of brown, which was not 
observed at any time on the plants receiving manganese. The etiolated 
condition became more pronounced as the time progressed and finally 
resulted in the top branches dying back. The green and dry weights of 
the 12 plants that grew in each of the 4 pots were determined. 
The average dry weights of the pea plants show an increase of 49.47 
per cent in the total dry matter produced in the plants which were 
grown in the presence of manganese when compared with those plants 
that grew in a Knop’s solution to which no manganese was added. 
There was also an increase of 24.63 per cent in the mineral nutrients 
assimilated, exclusive of nitrogen, in the plants that grew in the 
Knop’s solution containing manganese. The plants which did not 
get any manganese contained a little more nitrogen than those to 
which manganese was added. The plants from which manganese was 
withheld contained only traces of this element, which was no more 
than could have been derived from the seeds from which the plants 
grew. It therefore appears that the trace of manganese derived from the 
seeds of the plants was not sufficient to maintain a normal metabolic 
process during the latter part of the time the plants were growing. 
The duplicate sets of plants were combined to make a composite 
sample for chemical analysis and the results are given in Table V. 
Tabi^K V .—Analyses of pea, soybean, corn, and cowpea plants grown in media free from, 
and containing manganese {results expressed of the moisture-free material) 
Ash 
(crude). 
Iron 
(Fe). 
Man¬ 
ganese 
(Mn). 
Cal¬ 
cium 
(Ca). 
Mag¬ 
nesium 
(Mg). 
Potas¬ 
sium 
(K). 
Phos¬ 
phorus 
(P). 
Nitro¬ 
gen 
(N). 
Alaska pea plants: 
Per ct. 
Per ct. 
Per ct. 
Per ct. 
Per ct. 
Per ct. 
Per ct. 
Per ct. 
Manganese. 
12. 85 
0.041 
0.179 
1.85 
0. 50 
2.05 
0. 58 
2.97 
No manganese. 
IS- 41 
. 040 
Trace. 
2.41 
.98 
2. 71 
.68 
4 - 71 
Soybean leaves; 
Manganese. 
IS- 00 
.051 
.80 
-S6 
1.58 
. 62 
3 - 42 
No manganese. 
IS- 99 
.094 
Trace. 
.82 
. 62 
I. II 
.48 
3-85 
Soybean stalks; 
Manganese. 
13- 07 
• 036 
. 010 
•S 7 
•37 
1. 08 
•45 
I. 69 
No manganese. 
16. 67 
-033 
None. 
.68 
•39 
1-35 
.46 
2. 21 
Cowpea plants; 
Manganese. 
17- 24 
. 046 
.036 
I. 70 
•54 
S- S6 
.72 
2-57 
No manganese. 
20. 14 
.065 
• 003 
1-32 
. 61 
7. 88 
•SI 
4-51 
Com leaves: 
Manganese. 
8.71 
. 029 
. 040 
-23 
•31 
3. 80 
.40 
. 22 
No manganese. 
10. 28 
•034 
. 001 
• 24 
. .36 
4 - 07 
•35 
1.47 
Corn stalks: 
Manganese. 
6.37 
. 014 
.003 
. 08 
• 13 
3- 02 
.42 
•77 
No manganese. 
8. 24 
. on 
Trace. 
. 10 
• 13 
3 -S 2 
•37 
•95 
