Mar. io, 1923 Aluminum and Iron Compounds in Corn Plants 
811 
not its action was comparable to that of iron. Injections of various 
salts into normal-appearing stalks were made and the specific effects 
of single salts and of salts in various combinations were observed. In 
all cases a hill with two similar and apparently normal stalks was selected. 
The stalk not treated served as a control for comparison with the treated 
stalk. 
METHOD OF INJECTING THE SOLUTIONS 
The method which was used to introduce the chemicals into the 
plants for the study of their specific effects on the plant tissues was 
to insert a straight calcium-chlorid tube into the stalk just above the 
first node. The stalk was first punctured with a sharp cork borer of the 
same size as the small end of the tube. The tubes were inserted ap¬ 
proximately to the center of the stalk and then slightly exserted to form 
a small reservoir for the solutions so that they could be absorbed by 
some of the severed vascular bundles. Measured quantities of the test 
solutions were then placed in the tubes, and a stopper was placed loosely 
into the distal end. The method is illustrated in Plate 12, B. 
When the cortical tissues of the stalk were imperfectly cut the solu¬ 
tions would leak out, and in such cases the results were ignored. Only 
those cases where definite absorption of the solutions occurred have been 
considered. The quantities of the solutions which remained in the 
tubes at the end of the experiment were measured, and the total amounts 
were recorded. The quantities which were absorbed varied considerably 
for different solutes and the moisture content of the soil. 
Because of the wide range in the sizes of the plants which were treated 
and because of their heterozygous conditions also, no accurate quanti¬ 
tative studies have been considered worth while yet with the strains 
of corn available for study. Only plants which were apparently normal 
were used, and each group of plants experimented upon had their origin 
from the same seed ear. This tended to reduce the strain differences 
to a minimum. 
The injections were begun just at the time the plants began to tassel. 
They are difficult to make prior to this time because the cortical tissues 
are not usually mature enough to support the tubes rigidly. The relative 
proportion of the amount of stalk material to the quantity of solute 
injected can not be accurately determined because tie specific effects 
on the tissues of varying quantities of the solute are dependent upon 
a definite time relation. This, too, is affected by changing plant-volume 
and absorption-rate entities during* the time when injections are made. 
The metals which accumulate in the plants under normal seasonal con¬ 
ditions are absorbed by the plants in very dilute concentrations from the 
soil solution. The concentration of the metallic salts in the soil solution 
is therefore a most important factor in determining the length of time 
required to produce the specific effects of the metals. This difference in 
availability of these salts is often observed in fields within small areas. 
In Plate 17 the effects are shown on plants of dent and sweetcom, 
respectively, grown from seed taken from the same seed ears. The 
plants grew within 12 feet of each other, the stunted plants being taken 
from the ends of the rows in the soil with larger quantities of available 
metals. Sweetcom is markedly more affected by these soil conditions 
than dent. This has been observed many times in districts where both 
kinds are extensively grown. 
