638 
Journal of Agricultural Research 
Vol. XXIV. No. 7 
percent^e of iron m the ash was higher in the green plants, this was 
largely due to a high pro^rtion of silica in the ash of the chlorotic 
plants. The percentage of iron in the silica-free ash was about the same 
in the green and in the chlorotic plants. 
Such observations would indicate that the chlorosis in these pots was 
not due to a deficiency of iron, but Gile and Ageton (7) explained a 
Similar result in their work as possibly being due to the fact that the 
tissues of chlorotic plants represent an earlier period of growth than do 
the tissues of green pl^ts of the same age and that they therefore require 
a greater quantity of iron to prevent chlorosis. It would not be impos¬ 
sible, however, for iron in a chlorotic plant, though present in sufficient 
quantity, to be rendered inactive for the development of chlorophyll by 
abnoraal conditions in the plant. ^ 
It is shown that the ^een plants had an ash content which was less 
than that of the chlorotic plants, but the high ash content of the latter 
may have been due to the depression of carbon assimilation and to a 
consequent small quantity of carbonaceous matter in the plant. The high 
silica content of the chlorotic plants can best be explained in the same 
way, and variations in the amount of this constituent in the plant ash 
are apparently of no importance. 
In regard to the silica-free ash, the plants of all treatments had a 
general unifoimity of compositions at the same stage of growth but 
gave some evidence that the use of calcium nitrate as a fertilizer de¬ 
pressed the absorption of this constituent up to the tim e of the second 
cutting. It is hardly possible, however, that the silica-free ash content 
of the plant can be considered as indicative of the way in which nitrate 
fertilizer cause the development of chlorosis, because the analysis of 
plants in the second cutting from the nitrate pots showed that there 
was no consistent difference between the chlorotic and the green plants 
in this regard. 
As was shown of the nitrogen content, the rate of absorption of the 
ash constituents, with the exception of silica, tended toward diminution 
as the pl^t passed through the stage in which it began to recover from 
the condition causing chlorosis. It does not appear, however, that the 
analytical results presented offer an evidence that variation in the ash 
content of the plant at different periods of growth has any bearing on 
chlorosis. 
StJMMARY 
The development of chlorosis of rice on calcareous soils may be gov¬ 
erned by the natm-e of the nutrients supplied, those compounds repre¬ 
sented by sodium nitrate, calcium nitrate, and ammonium phosphate, 
which, in themselves or by virtue .of an unassimilable ion, are the cause 
of the precipitation of iron, being associated with chlorosis, while the 
plants which have been supplied with ammonium sulphate in which 
the unassimilable radicle may serve as a solvent for iron may be thrifty 
and of normal color. 
It h^ not been shown by the experimental methods used whether 
the basic material in the soil or the basic residues of the nitrates were 
primarily the cause of the conditions determining the appearance of 
chlorosis, nor whether the acidic residue of ammonium sulphate served 
to prevent chlorosis in the calcareous soil. Inasmuch, however, as it 
was shown in the first experiment that the degree of chlorosis attending 
the use of sodium nitrate as a nutrient was in proportion to the quantity 
