Mar. io, 1923 
Aluminum and Iron Compounds in Corn Plants 813 
Aluminum-chlorid, aluminum-nitrate (PI. 11), iron-citrate (PI. 18, A), 
and ferrous-sulphate injections (PI. 18, B) caused marked injurious 
effects upon the vascular plate tissues, while iron nitrate (PL 18, C) and 
iron chlorid (PL 18, D) accumulated in the vascular plate tissues without 
producing any marked injury to either the leaves or vascular plates. 
These accumulations were detected by testing the tissues chemically. 
Acetic, citric, tartaric, phosphoric, and malic acids in 1 per cent con¬ 
centrations caused no injurious effects that could be noticed in the 
plants. In fact, the plants receiving the malic and phosphoric acids 
appeared greener and healthier than the control plants. Formic acid, 
however, proved to be harmful, the plants dying within two days. The 
r 61 e of the organic acids in relation to the availability of the metallic 
salts is being investigated further. Maz£ (16) reports that malic acid is 
secreted by the roots of the corn plants and has an important bearing 
upon the absorption of the plant nutrients. 
The chief purpose of the injection studies was to determine the specific 
effects of the iron and aluminum salts. The effect of aluminum nitrate 
upon the com plant tissues is shown in Plate 11, A and B. The ultimate 
effect upon the leaf tissues consists of a killing of the intervascular leaf 
tissues and a destruction of the nodal vascular plate tissues. The prog¬ 
ress of this action on these tissues is of much interest because the symp¬ 
toms of various stages resemble closely certain of the symptoms which 
become prominent during the progress of development of the injuries in 
the stalk and leaves associated with the rootrot disease in soils with 
available aluminum salts. 
Of a 1 per cent solution of aluminum nitrate 5 c. c. was sufficient to 
cause the effects shown in Plate 11, A. The quantity of aluminum ions 
was less than 9 mgm. It is seen then that a sudden increase in the 
aluminum-ion content of the stalk is disastrous and that the quantity 
that is necessary is exceedingly small. 
Aluminum chlorid is also very toxic, but in this case the action of 
chlorine ions may have played a part in the injuries. These effects will 
be studied further. In this relation the effects of N/20 hydrochloric 
add should be noted. No injury to the nodal plate tissues resulted 
from the introduction of 30 c. c. of the acid. From these results it is 
evident that the aluminum ions are the toxic ones. 
When N/100 aluminum nitrate was injected into the stalks the injury 
to the leaf tissues developed slowly, the first effect being a slight yellow¬ 
ing of the intervascular tissues at the distal end of the leaves. The 
yellowing of the tissues was followed by a complete disappearance of 
the chlorophyll and this by a water-soaked appearance of the tissues. 
The affected tissues then became dry and brown, and the leaves presented 
the streaked appearance shown in Plate 11, B. The stages in the prog¬ 
ress of the injury to the nodal tissues were observed in a number of 
plants. The accumulation was most pronounced in the vascular plate 
tissues, although the aluminum salts combine with the cell contents of 
the phloem cells along the entire vascular bundles through which they 
are being conducted. The vascular plate tissues (zone B in Pl. 3, A) 
first become yellowish brown in color, then brown, and with the deepen¬ 
ing of the brown color the disintegration of the tissues can be noted. 
The advanced stages of this disintegration are shown in Plate 11, A. 
