, 1888-07-28

pr0DaOlIlty, that the results may nave
been affected by liberation of nitrogen
from seeds or plants or food supplied-a
liberation which is sometimes, if not al
ways, due to fermentS. This may materi-
ally reduce the nitrogen found at the
end of the experiments, and with it the
apparent gain of nitrogen from the air.
The evidence from the field against the
assimilation is of necessity more or less
incomplete, since-tO say nothing of other
dit1iCulties-SOme of the important factors
of the problem, such as the acquisition of
nitrogen by the soil and it's liberation
from the soil, are inadequately settled or
left entirely out Of account. And, finally,
to deny the acquisition of atmospheric hi.
tr0Sen is to leave some of the most evi.
dent facts OF production unexplained.
On the other hand, the evidence in fl.
YOUR of the acquisition of nitrogen by
plants, legumeS especially, from the at
mOSphere during their period of growth,
is direct and positive. In pot experiments
the gain has been at times very large, and
in comparative trials it has been larger or
smaller in proportion as the conditions
have been more or less nearly normal.
Lass accurate, but ut the same time very
strong, evidence in the same direction
comes from experiments in the field The
conclusion hat plants acquire atm0Sphe-
rio nitrogen accOrdS with and explains FACTS,
of vegetable production otherwise unex-
planned. And late research leads us to
hope that the explanation of the process
SEES by which nitrogen is acquired may be
found, perhaps, in the near future.
1t is reasonably certain that the com
bined nitrogen OF the atmosphere is ASST
inflated by plants. If the results of re-
search should continue to develop in the
same direction i'll which they have been
developing OF late, it will require but %
short time to place the assimilation of free
nitrogen beyond question. Unless future
research should bring evidence directly
opposed to the best now at hand it must
be allowed that the greater part of the nj
trogen which the plants obtain from the
air zones through the foliage. The facul-
ty Of obtaining nitrogen from the air ap-
ptarS to oa especially characteristic Of
the ~legumeS, BY what species Of legumeS
or other families OF plants it is possessed
it is Is yet impossible to say.
But whatever may be the plants that
acquire atmospheric nitrogen, the ways by
which they acquire it, or the form in
which it comes, the fact of its acquisition
in considerable quantities seems we'll es-
tabliShed.
Professor Hellriegel of Germany in 1887
announced experiments in which legumi.
nous plants were found to obtain large
quantities. Of nitrogen directly from the
air, under conditions which led him to be-
lieve that they assjmilated free nitrogen
by the aid of micro, organisms. He said :.
"Tho papillonace8 are not dependent
upon the soil for the nitrogen of their food.
The source OF nitrogen which the atmoS-
phere offers ctn alone suffice to bring
them to normal. indeed, luxuriant develop
ment.
1t is not the small quantities of the com.
bined nitrogen in the air which supplies.
the papilionaceB with nutriment, but the.
free nitrogen of tho air comes into play {;
and there is a direct relation between the
assimilation and the noduleS on the roots
of the leguminOuS plants. That is, the
growth of the papilionaceB 10 soil free
from nitrogen can be caused at will by the
addition of small quantities OF cultivated.
soil, and can be hindered by excluding
heterogeneous" w.
Professor Wolff, the Nestor of German
agricultural chemists, was present at the
meeting when these experiments were an
nOunced, and cited some experiments Of
his W which confirmed Professor He'll
riegel's conclusions.
1t should be added that in his last pa.
per Professor Hellriegel speaks quite
guardedly of the nOdules and the micro.
organisms and their relation to the assimi.