The Florida agriculturist. [volume] (DeLand, Fla.) 1878-1911, 1896-08-26


they produce. In such plants in state
of maturity, as was mentioned above,
are found larger quantities of organic
nitrogen than could possibly have been
derived from the soil in which they were
grown or from the fertilizers with which
they are supplied. Cultural experiments
in sterilized soils, with careful exclusion
of all sources of organic nitrogen, have
proved beyond question that this gain
in nitrogen is found only in such plants
as are infected by the organism men
toned. The logical conclusion is there
fore inevitable that these organisms, in
their symbolic development with the
plant rootlets, assimilate and oxidiZe the
free nitrogen Of the air and present it to
the plant in a form suited to absorption.
Attempts have been made to innoculate
the rootlets of other families of plants
with these organisms, but so far with
out any pronounced success. There are,
however, certain orders of low vegetable
life, such as cryptogams, for instance,
which seem to share to certain degree
the faculty OF the leguminous plants in
acting as host for the nitrifying or
ganiSmS mentioned. The observation
above recorded becomes sufficient ex
PLANTATION of the fact that the fertility Of
fields is increased by the cultivation of
leguminous plants, which would not be
possible except they could develop some
such property as that which has already
been described.
Another order of organisms has also
been discovered which is capable of oxi-
dizing free nitrogen when cultivated in
an environment from which organic nj
trogen is rigidly excluded. 1t seems
probable, therefore, even in soils which
bear crops not capable of developing
nj flying Organisms on their roOtlets it
is possible that the actual stores of
nvaila Die nitrogen may be increased.
This fact explains the observation which
has frequently been made that in the
fields which are not cultivated but which
remain in grass there may be found an
actual increase in the total amount of
nitrogen which is available for plant
growth. AS will be seen further along,
the soil is also infested with an organ
ism which is capable Of destroying nitric
acid and returning the nitrogen which
it contains in the air in free state. 1t
seems almost certain that in every COM
plete decom position of heterogeneous
organism part of the nitrogen which
it contains escapes in the free state.
Were it not, therefore, for the fact that
this free nitrogen can be again oxidiZed
and made available for plant growth the
total stores of organic nitrogen in exist
ence would be gradually diminished, and
the time would ultimately come when
their total amount would not be suf-
ficient to sustain a plant life abundant
enough to supply the food of the animal
kingdom. Thus the earth itself, even
without becoming too cold for the exist
ence of the life which is now found
upon it, might reach state when plant
and animal life would become practi-
cally i'm possible by reason of the deficit
of heterogeneous foods.
Much less is known concerning the
character and activity of the organisms
that oxldize free nitrogen than of those
which feed upon organic nitrogen. 1t
can not be doubted, however, that these