THE VALUE OF CERTAIN NUTRITIVE ELEMENTS IN THE 
DEVELOPMENT OF THE OAT PLANT 
James Geere Dickson 
Introduction 
It has long been recognized that the incombustible residue resulting 
from the incineration of a plant is of great importance, and a large 
amount of work has been done to determine the chemical combinations 
resulting from the incineration, since by this means it was hoped 
to determine the nutritive elements which are essential to the plant. 
This method has proven only partially successful. Liebig (1855), 
basing his conclusions upon water culture methods, advanced the view 
that certain salts are indispensable to plant development and main- 
tained that the productiveness of the soil is determined by the essential 
salts present. Liebig's hypothesis stimulated research, and it was 
later determined that six ash constituents are essential to the growth 
of phanerogams, viz., calcium, magnesium, potassium, sulphur, phos- 
phorus, and iron, to which should be added nitrogen, a constituent not 
found in the ash. 
Many similar experiments confirmed these results, but the general 
trend of investigation soon changed to the study of the function of the 
elements thus shown to be essential. Various writers, more recently 
Chirikov (1914) and Truog (1916), have attributed to calcium the 
function of acting as a carrier of the essential phosphoric acid and as 
a neutralizer of the organic acids formed in protein synthesis. In 
agreement with several early workers, Hansteen (1910) has described 
calcium as functioning in the transformation and transfer of carbo- 
hydrates and in the formation of cell walls by green plants. On the 
other hand, Robert (191 1, 1912), confirming the results of earlier 
investigators, has shown that calcium is not an essential element in the 
nutrition of fungi, and Molisch (1895) has found that certain algae 
can thrive without calcium. The effect of calcium in reducing the 
toxic action of other bases, notably magnesium, in the culture solution 
has been studied especially by Loeb (1906), Osterhout (1906a, 1908, 
1911, 1912, 1916), and McCool (1913). 
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