14 T. L. Lyon anv J. K. WiLson 
which represented samples left in the field and in the shock, for the former 
a loss of about 23 pounds was shown, while for the latter a slight gain 
was reported. This loss of nitrogen when the plants were left in the 
field after October 8 was from both ears and stalks. In the former there 
was a loss of 9.2 pounds in the field and a gain of 7.6 pounds in the shock; 
in the latter there was a loss of 15 pounds in the field and a loss of an 
2.1 pounds in the shock. 
Taking the results of these investigations as a whole, there appears 
to be in nearly all cases a loss of nitrogen from grass and small grains at 
some time between the period of full bloom and complete maturity. 
In maize this occurs if the plants are allowed to ripen when connected with 
the roots, but potatoes showed no loss of nitrogen in the Bernburg and 
Australia experiments, and only a small loss in those of Le Clere and 
Breazeale. 
OBJECT OF THE PRESENT EXPERIMENTS 
The experiments herein described had two more or less distinct objects’ 
The first was to ascertain whether growing plants liberate organic matter’ 
and, if they do, to determine at what stage of growth this takes place 
and what relation it bears to the absorption of nitrate nitrogen by the 
plant. The second object was to detect, if possible, the presence of 
reducing and oxidizing ferments in the nutrient solutions in which the 
plants used for the first investigation were grown. 
METHODS USED 
The plants used in these experiments were grown in water culture. 
This was done in order that an intimate study might be made of the 
plant as it grew and the solution as it was being drawn upon by the plant 
for various nutrients, especially nitrogen. Since a number of organic 
bodies may be given off by the developing plant, these may not be present 
when the nutrient solution is analyzed if it is allowed to become infected 
with molds or bacteria. Therefore, in order that this solution should 
represent the action of the plant alone, a method for growing the root 
system in contact with the nutrient solution without infection was used. 
This method has been published, together with data showing its reliability 
(Wilson, 1920). A description of the method follows, 
