802 
Journal of Agricultural Research 
Vol XXIII, No. to 
nodal troubles are most abundant. The types of soil which are high in 
organic matter and low in calcium and phosphorus seem to be the best 
environment for the development of seedling-blight. Because of these 
relations an attempt was made to ascertain the cause of the brownish 
purple discolorations of the vascular plate. Microchemical tests made 
upon these discolored tissues proved the presence of organic compounds 
of iron and aluminum in them. 
The purpose of this paper is to discuss the methods used to detect 
these metallic accumulations and the methods used to determine the 
cause of the nodal discolorations and subsequent disintegrations and 
their probable importance in relation to the development of the rootrots, 
stalkrots, and earrots of com. 
OCCURRENCE OF IRON AND ALUMINUM IN PLANTS 
Iron compounds are essential to the normal development of all green 
plants. Their importance has been demonstrated by numerous experi¬ 
ments, the history of which needs no reference here. Chlorosis, which 
has been directly referable to conditions which develop in the plant 
and which is associated with deficient quantities of available iron salts, 
is well known and its causes are more or less understood. 
Less is known regarding the occurrence of aluminum in plants, although 
considerable work has been done in the study of its r 61 e in the soil as a 
factor affecting the growth of plants, both as a stimulant and as a toxic 
agent. 
Maz 4 (17) 2 believes that the presence of aluminum in the soil is neces¬ 
sary for the normal development of maize. He also includes iodin, 
fluorin, and boron as being necessary. True, Black, and Kelley (25) 
report a higher aluminum content of the tops of spinach when the plants 
are diseased than when they are healthy. Kratzmann (14) reports the 
ash content of the leaves of maize to contain 2.35 per cent of aluminum. 
A study of 130 different plants showed that aluminum is widely dis¬ 
tributed, and the unusually large quantities present in some plants 
suggested that certain species may be ‘ * aluminophilous. 1 ’ According 
to Kratzmann, different plants possess a specific elective power toward 
aluminum. Two plants of different species may accumulate widely 
different quantities of aluminum even though grown close together. 
This same phenomenon of varying capacities for the absorption of 
aluminum by different plants seems to apply equally well to different 
individuals within a definite variety of com, or even to individual plants 
grown from different kernels from the same seed ear. These differences 
may be interpreted as being due to the heterozygosity of the strain of 
com. Qualitative tests for iron and aluminum applied to many plants 
studied in the rootrot investigations show very variable amounts of 
iron and aluminum in different stalks. From these observations it is 
evident that Kratzmann’s designation of specific elective powers of 
plants for aluminum applies to com for both aluminum and iron. The 
conditions which develop in the com plant when large quantities of 
iron and aluminum salts enter the plant and concentrate in certain tissues 
have not been studied so far as can be learned. 
* Reference is made by number (italic) to literature cited/' pp. 822-823. 
