Z 
LIBERATION OF ORGANIC MATTER BY Roots oF GROWING PLAaNts 41 
ested for sterility and analyzed for nitrates, nitrites, ammonia, and 
rganic nitrogen, and in some cases for total organic matter. A determi- 
ation of organic nitrogen in the deposit at the bottom of the flasks was 
lso made. . 
The plants grown were maize, oats, peas, and vetch. The nutrient 
olutions in which each of these plants grew contained nitrogen only 
ithe form of nitrate when the plants were set in the flasks, but when the 
lants had grown for several weeks there was always organic nitrogen 
resent. Even before the nitrate nitrogen had all been absorbed by the 
lants, organic nitrogen appeared in the solutions. 
The deposit at the bottom of each flask contained a small quantity 
f organic nitrogen, which was probably derived from sloughing off of the 
»0t cells as indicated by the presence of plates of cells in the deposit. 
here was no direct evidence that the organic nitrogen in solution was 
berated in any other way, but it is questionable whether such a large 
aantity could all come from these cells, especially during the early stages 
* growth. 
A pea plant which grew in a solution without the addition of combined 
trogen liberated organic nitrogen into the solution in which it grew. 
he growth was by no means as vigorous as that of another pea plant 
hich was furnished with nitrate nitrogen, and the plant itself contained 
ily about one-fifth as much nitrogen as did the latter plant, but it 
erated more than half as much organic nitrogen. 
A series of flasks in which maize was growing were harvested at successive 
ages in the growth of that plant, and the plant and the flask contents 
are examined in the manner already described. Organic nitrogen 
ypeared in the solutions at all stages in the growth of the plants, but 
Pere seemed to be a tendency for it to decrease in amount with pro- 
essive stages in the life of the plant and especially as the plant closely 
proached maturity. The organic nitrogen in the deposit at the bottom 
the flasks did not show any decided tendency to vary in amount with 
e successive stages of plant growth. 
Determinations of total organic matter were made in the solutions 
4#m some of the flasks. This constituent was very large in amount 
4 compared with the nitrogenous organic matter present. Apparently 
dere was much non-nitrogenous organic matter in the solutions. Calcu- 
ing the nitrogenous organic matter at 6.25 times the nitrogen present, 
