792 
Journal of Agricultural Research 
Vol. XXIV, No. 9 
which the increase in dry weight of the plants receiving manganese was 
134-5 cent. All the leguminous plants from which manganese was 
withheld made a normal growth for the first six or eight weeks; there¬ 
after the young buds and leaves as they unfolded were etiolated and 
brown specks developed on the etiolated leaves later. After this condi¬ 
tion had developed but very little growth was made, and the young and 
tender parts of the plants died back, while the plants to which manga¬ 
nese was added made a normal growth and no chlorosis developed during 
their growth. With corn, the only apparent effect produced on the 
growth of the plants was the failure in the production of dry organic 
matter. No chlorosis developed on the leaves of the corn, which was 
harvested after the plants had produced tassels. From these results it 
appears that leguminous plants are more sensitive towards the lack of 
manganese than are the nonlegumes. 
In the cowpea and corn plants to which no manganese was added, 
enough of this element was present for a determination. In the other 
plants to which no manganese was added only a trace of manganese 
could be detected. 
The stalk of the soybean plants which grew in the absence of manga¬ 
nese was the only material in which no manganese could be detected. 
The plants which grew in the pot cultures to which manganese was 
added contained a normal amount of this element. 
More recent experiments with manganese-free sand cultures at the 
Kentucky Agricultural Experiment Station have shown the necessity of 
manganese in both nonleguminous and leguminous plants. 
Plate 2, A, shows in a very striking way the beneficial influence of 
manganese on oats. The plants on the left had no manganese added 
to the sand in which they grew, while those on the right grew in the 
presence of manganese. 
Plate 2, B, shows Canada field peas. The plants on the left received 
no manganese in the sand in which they grew, while to those on the 
right manganese was added, all other conditions being the same. 
Sand cultures were carried out with the following species of plants: 
Wheat, oats, peas, cowpeas, beans, lettuce, tomatoes, onions, spinach, 
cabbage, carrots, radish, and clover, and similar effects were observed 
as those described and shown in Plate 2, A, B. 
SUMMARY 
(1) In the experiments with acid soil which contained approximately 
one-tenth of i per cent of manganese it was found that only small 
amounts of the total manganese were soluble in water. Applications of 
more manganese, in the form of the sulphate, to the acid soil caused a 
decrease in the yields of the crops, whereas like quantities of this com¬ 
pound, when applied to different portions of the same soil, after addition 
of calcium carbonate, caused an increase in the yields of other plants of 
the same species. 
(2) The occurrence of soluble salts of manganese in an acid soil may 
be one of the causes of toxicity in such soils as exhibit toxic effects. 
An excess of manganese sulphate in a soil renders it sterile with respect 
to the growth of plants. Calcium carbonate in the soil causes a diminu¬ 
tion in the toxic effects produced by an excess of manganese sulphate. 
(3) In order to demonstrate whether or not manganese is essential 
for the normal growth of plants, it is necessary that great care should 
