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AMERICAN JOURNAL OF BOTANY 
IVol. 10, 
and only once, when the cultures were six weeks old, was there an addition 
of distilled water ranging from 300 to 500 cc. per culture to make up for 
the loss in transpiration of water by the plants. One half cc. of 0.01 
molecular solution of FeS 0 4 was added to each culture at the beginning of 
the experiment, as it was known that, if a small trace of iron was not added 
to the tap water, the culture would soon turn yellow and die. All the 
varieties matured and produced grain. The first variety to mature ripened 
during the last week of June, and the last during the first week of August. 
The amount of grain produced obviously was small. The yield differed 
markedly with the varieties, but the results were consistent for each variety. 
These differences in yield of grain obtained appear to bear in no small 
measure upon a principle that determines adaptation of varieties of wheat 
(and perhaps of other species of plants) to the supply of nutrients in the 
growth medium. This phase of the experiment will be treated in another 
. paper. 
It was found, when the results of the two tests were compared, that the 
order of the maturity of the varieties was not the same in the two cases. 
The variety that ripened first of those grown in soil was the fifth of the 
varieties to mature when grown in tap water. Therefore, the effect of tap 
water, a poor growth medium, deficient in the essential salt nutrients, 
plus whatever effect the then prevailing climatic complex had, was to permit 
the alteration of the order of maturity of the varieties from that obtained 
by growing wheat in fertile soil. The obvious result of this change was to 
make a wheat, which was early under a given set of conditions, relatively 
late under the other set of conditions. Or, stated in another way, physio- 
Table 1. Differences in Order of Maturity and Change in Awned Characters of Different 
Varieties of Wheat , Grown in Soils and Tap Water (Medium Deficient in Nutrients) 
Name of Variety 
Order of Maturity 
Change of Awned Characters 
Soil 
Tap Water 
Bunyip. 
1 
5 
No change 
Cedar. 
2 
1 
No change 
Hard Federation. 
3 
4 
No change 
F ulcast.er. 
4 
3 
No change 
Sonora. 
5 
2 
7 percent of the plants produced awns 
when grown in tap water; all awnless 
in soil cultures 
Early Baart. 
Dart’s Imperial. 
6 
6 
No change 
7 
7 
No change 
White Australian. 
8 
9 
No change 
Marquis. 
9 
8 
No change 
logical conditions had a profound influence in determining whether certain 
varieties of wheat become relatively early or relatively late. 
Another genetic character of wheat altered by growing the plants in 
