Mar io, x 9 2 3 Aluminum and Iron Compounds in Corn Plants 
8 i 7 
It has been learned that certain soils vary within a few feet, and for this 
reason some of the plants which became diseased may have had larger 
quantities of these salts for absorption. This soil condition is frequently 
found in many fields, as is illustrated in Plate 4, A. 
Plate 17 shows two plants growing from the same seed ear. The 
plants were grown within 12 feet of each other. The soil in which the 
normal plant grew gave no reaction for available iron and aluminum, 
while the soil in which the stunted plant grew had a lime requirement of 
1,100 pounds per acre. Plate 19 shows this marked difference in the 
rates of growth in a field. The tall plants were growing in a soil which 
gave no reaction for available iron or aluminum and also reacted basically 
to the extent of an equivalent of 600 pounds of lime per acre. A sample 
taken from the soil where the stunted plants were growing showed the 
presence of available aluminum and iron salts, and a lime requirement 
of 900 pounds per acre. * The plants in this part of the field were badly 
rootrotted on June 30, 1921, while those growing in the better soil had 
no rot lesions on the roots. 
The ash of normal stalks contains approximately 2 per cent of alumi¬ 
num (A 1 2 0 ) 3 , but when the proportion increases the pathological phe¬ 
nomena of stunted growth, leaf streaking, nodal-tissue discoloration and 
disintegration, broken shanks, and premature death of the stalks may 
develop. The nature of the symptoms, of course, is dependent upon the 
relative availability of the aluminum and iron salts in the soil and the 
meteorological conditions favoring the growth of the corn plants. 
EFFECTS OF METALS ON FUNCTIONING OF VASCULAR BUNDLES 
Many plants which wilted and died prematurely have been studied. 
When stalks in various stages of disease are cut near the base and placed 
immediately in tap water colored with methylene blue it will be found 
that a number of the vascular bundles are not functioning. Plate 20, A-C, 
and Plate 1, B, show longitudinal and cross sections through a diseased 
stalk. Note the small number of functioning bundles as contrasted with 
sections through a similarly treated normal-appearing stalk, as shown 
in Plate 21, A and B, and in Plate 1, A. It has been found that the central 
bundles in the stalk cease functioning first, and when longitudinal 
sections are made through the stalks and tested chemically for iron 
and aluminum, these are the ones which give the reactions for the'largest 
quantities of accumulated metals in the vascular plate tissues. 
This plugging of the vascular bundles is a common effect of various 
solutions of the metals when absorbed by corn plants. Aluminum salts 
are especially active in this regard. It has been found in experiments 
that plants wilt very rapidly when cut and placed in N/100 solution of 
aluminum nitrate, whereas in the same concentration of ferrous sulphate 
larger quantities are absorbed before wilting begins. This latter type of 
wilting, due to ferrous sulphate, is subsequent to marked leaf-tissue 
injuries, whereas the wilting due to the aluminum usually precedes the 
leaf-tissue injuries. The physiological-chemical interpretation of this 
action is not known. Neither is the physiological effect of the metal 
salts upon the phloem tissues known. The changes which occur in plants 
with large quantities of metals in their tissues offer many problems 
which must be solved according to their influence upon the functions 
of the different tissues, such as absorption, transpiration, translocation, 
