22 
BULLETIN 52, HAWAII EXPERIMENT STATION. 
Manganese dioxid with 5, 10, and 20 milligrams of iron per liter 
from ferric citrate and 18 milligrams per liter of manganese from 
manganous sulphate (0.005 per cent manganous sulphate) caused a 
strong chlorosis and a severe depression in growth. Chlorosis was 
overcome and growth increased as a result of dipping the leaves in 
solutions of ferric citrate. The chlorotic effect of manganese was 
overcome and the weights approached those of the checks when 
the supply of iron in the solution was increased to 40 and 80 milli- 
FlG. 4. 
& JO 20 40 &O 
(Results of Experiment VI.) Effect of calcium carbonate and manganese dioxid on the growth of 
rice in nutrient solutions supplied with various amounts of iron from ferrous sulphate. 
grams. Here, where there were no harmful effects due to the pres- 
ence of excessive iron in the solutions, increased growth was not 
made, because of the presence of manganese dioxid. 
Experiment VI. — Since the action of manganese in causing chlo- 
rosis is similar to that of calcium carbonate, this experiment was made 
to determine the effects of the latter. 
The weights of the plants on the fortieth day are given in Table 
14 and graphically in Figure 4. 
