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AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
down, as if the openings had been enlarged through the disintegration of 
adjoining cells. In corn roots with well developed openings, fragments of 
cell walls are often seen projecting into the openings, as shown in figure 3. 
In a wheat root that has been growing fairly rapidly for a period of eight 
days, the openings are i or 2 cortical cells in diameter and are nearly spheri- 
cal. At a later stage about nine openings are seen in a cross section of the 
root, separated by septa composed of one or two layers of unmodified cortical 
cells. 
It was thought that this occurrence might be due to lack of proper 
physiological balance in the nutrient medium. The single-salt solutions 
each contained only two of the six essential elements, and there was no 
evidence that the 3-salt solutions employed were well balanced; moreover 
they had not been renewed as frequently as is customar}^ in water-culture 
work. This suggestion was tested by employing Shive's solutions R1C2 
and R2C5 (optimal series), which are to be regarded as at least fairly 
well balanced for wheat. The solutions were renewed on the fourth day and 
the cultures were continued for 10 days, beginning March i. Openings 
appeared just as before, being visible on the fifth day and well developed 
on the seventh. 
Beginning about the middle of June a few experiments were carried out 
for the sake of further observations on the openings in question. Cultures 
were grown in Shive's solution R5C2 (sub-optimal series), in a good garden 
soil and in sand. Marquis wheat, from the lot of seed used in the cooper- 
ative project of the Division of Biology and Agriculture, of the National 
Research Council was used, and the water-culture seedlings were supported 
by perforated cork stoppers in pint "Mason" jars. 
The solution cultures were in the greenhouse at temperatures varying 
between 25°-45° C. Some of the solutions were renewed daily for the 
first three days, but this treatment seemed to exert no influence on the 
formation of the openings, which appeared at about the same time and in 
the same way in all cultures. 
Rather large intercellular spaces were observed on the fifth day. Two 
days later a cross section of the region 4-6 cm. below the seed appeared as 
is shown in figure i. On the ninth day the openings were larger and pre- 
sented the appearance shown in figure 2. The roots were then 18 cm. long 
and openings were present 2 to 14 cm. below the seed, those toward the 
tip of the root being smaller. The smaller openings certainly contained gas. 
All the plants of these solution cultures appeared to be healthy and vigorous 
throughout the experiment; on the thirteenth day, when the cultures were 
discontinued, the shoots were about 19 cm. high. 
The sand and soil cultures mentioned above were continued for 13 
days in the greenhouse, at temperatures between 25° and 45° C, the media 
1 Livingston, B. E. A plan for cooperative research on the salt requirements of 
representative agricultural plants. Baltimore, 1919. 
