LIBERATION OF ORGANIC MatTrTer By Roots oF GRowING PLANTS 33 
7 parts in the plant, which was the narrowest ratio, to one part in the 
ution to 65.3 parts in the plant, which was the widest ratio. If it is 
) be assumed that the decomposition of this organic matter in the soil 
ould increase its liberation by the plant, the result would be that a very 
rge quantity of organic matter would be transferred to the soil. It is 
itirely conceivable that higher plants may influence bacterial activity 
the soil by means of this liberation of organic matter, which would 
rnish a source of energy for certain bacteria, as, for instance; nitrate 
nsumers. 
In the solutions in which these four plants grew there were at harvest 
) ammonia, no nitrates, and very little organic nitrogen, which condition 
dicates a strong demand for nitrogen by the plants. Sometimes 
amoniacal nitrogen was found to be present in the solutions and some- 
nes it was absent. The cause of its formation is an unsolved problem. 
wo possibilities present themselves. One is that ammonification of the 
ganic matter in the solution took place between the time when the 
sk was opened and the time when the test for ammonia was made, 
ntamination of the solution from outside occurring after the flask was 
ened. This was guarded against as far as possible. Another hypoth- 
s is that ammonia formation was due to enzymic action, the plants 
ving liberated the necessary enzymes. 
Possibly ammonia is commonly formed and when the demand of the 
nts for nitrogen is great it is absorbed and thus disappears from the 
ution. If it is derived from the liberated organic nitrogen, as seems 
ssible, it may be the means by which organic nitrogen is rendered 
ailable to higher plants. 
In a previous experiment, flasks were opened at four different stages in 
> growth of maize. As the periods of growth varied from a rather 
‘ly stage, before the nitrate nitrogen was all removed from the solution, 
maturity, it would have been a very interesting experiment had it not 
on for the fact that the last two flasks opened were found to be con- 
ninated. The data, however, are all tabulated in table 4, altho there 
of course, no assurance that the results were not materially affected 
the organisms that had gained access to the solutions. 
he sterile flasks in this experiment agree with those in the experiment 
orded in table 3 in showing the presence of a large amount of organic 
tter in the solution in which the plants grew. The amount was less 
