264 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
Phospholipins, nuclein and nucleic acid, phytin, and possibly starch con- 
tain phosphorus in chemical combination. In addition to these organic 
compounds, some inorganically combined phosphates are stored in the 
seed, and often large quantities are deposited in the straw of the cereals. 
Probably, lecithin and phytin are the only organic compounds containing 
phosphorus which are accumulated as reserves in the seed, and which are, 
therefore, subject to variation due to the supply of phosphorus. Parrozzani 
(1908) found that the percentages of both lecithin and phytin phosphorus 
were increased by the addition of mineral phosphate fertilizers to the soil. 
The nuclein phosphorus, on the other hand, was quite constant, showing no 
change even with the most varied phosphorus fertilization. Jakouchkine 
(19 1 5) stated that the amount of phytin in the grain is apparently dependent 
on the condition of the soil. Generally only small amounts of inorganically 
combined phosphorus are stored in the grain; therefore, if the total phos- 
phorus of the grain varies with varying amounts in the soil, it is probably 
due to the varying amounts of the organic reserve materials containing 
phosphorus. An organic analysis is necessary to disclose these relations 
and is planned in further pursuit of this problem. 
The composition of the grain from plants grown in culture solutions 
having a deficiency of certain nutrient elements, especially of phosphorus, 
is modified very markedly. The average percentages of total phosphorus 
in the grain from plants grown in the different culture solutions are given 
in table 6. 
Table 6. The Average Phosphorus Content of Grain from Plants Grown in the Normal 
Solution, and in Solutions with One Nutrient Element in Each Case Reduced to One Tenth 
the Normal Amount 
Solution, Deficient Element 
Given 
Percent P2O5 in Grain 
1915 Crop 
1916 Crop 
1917 Crop 
Average 
Normal 
0.673 
1.047 
1.900 
1.206 
Ca 0.1 
0.946 
1. 017 
2.130 
1.364 
Mg 0.1 
1.720 
1.092 
K 0.1 
0.625 
0.963 
1.665 . 
1.084 
P 0.1 
0.472 
0.732 
0453 
0.552 
N 0.1 
1. 121 
1.552 
1-336 
The phosphorus composition of the check plants which were grown in 
a complete nutrient solution varies over the three years* experiments. 
These variations for the different years will be discussed later under another 
heading. The phosphorus content of the grain from the plants grown in 
the calcium-deficient solutions is the highest of any of the series, the average 
content for the three years being 0.158 percent higher than the composition 
of the grain from the checks. The explanation for this extra high phos- 
phorus content may be sought from two diflferent sources : first, the calcium- 
magnesium ratio of the Knop's solution may not be the best for maximum 
