LIBERATION OF OrGANIC Matter By Roots oF Growine PLANts 23 
ORGANIC NITROGEN PRESENT IN NUTRIENT SOLUTIONS AT 
SUCCESSIVE STAGES IN THE GROWTH OF MAIZE 
In order to ascertain how the stage of growth of maize plants affects 
the quantity of organic nitrogen found in the nutrient media, a series 
of flasks containing nutrient solution were prepared in the usual way 
and a young plant was set in each flask. The flasks were placed in the 
greenhouse on December 24, 1915. They were allowed to remain there 
until the time when they were to be brought to the laboratory for analysis 
of the plants and the contents of the flasks. The first flask was opened 
on March 4, 1916, and the others were opened at intervals of a number 
of days until May 24, 1916, when the last one was opened. The interval 
between the opening of the first and that of the last flask covers a period 
of growth between the pre-tassel stage and maturity (figs. 5 to 9). 
The maize plants grew well and most of those that were old enough 
at harvest bore ears. The variety used was a pop corn which under 
normal conditions does not grow very tall. Data regarding all of the 
flasks the contents of which were sterile at harvest are given in table 2. 
All of the contaminated flasks except one were discarded in presenting 
the results. ‘The one exception was made because it fell in what would 
otherwise have been a wide interval between the dates of harvest. It also 
represented the condition of most of the contaminated flasks, which did 
not appear to be materially different from the sterile flasks in respect 
to the quantity of organic nitrogen present in the nutrient solution. 
The data in table 2 are consistent in showing the presence of organic 
nitrogen in all solutions in which plants grew. This organic nitrogen 
appeared at all stages in the growth of the plants, but there seemed to be 
a tendency for it to decrease in amount with progressive stages in the 
life of the plant, and especially about the time when the plant approached 
maturity, at which stage there was a very decided falling off in the quantity 
present. 
The organic nitrogen in the deposit at the bottom of the flask did not 
show any decided tendency to vary in amount with the successive stages 
of plant growth. The amount present was uniformly smaller than that 
ia the solution. In the bottom of the flask there could usually be found 
plant cells, indicating the sloughing off of root caps and root hairs. This 
Suggests a possible source of at least a part of the organic nitrogen in 
