, 1890-07-16

rlegel, q German chemist, commenced OK"
perimentS on plants grown in pots OF VAST
ed quartz sand. To all the pots he added
nutritive solutions containing no nitrogen /;
to one series nothing but these non nitro
genOuS fertilizers; to a second, a fixed
quantity of nitrate Of soda, to a third twice
as much and to a fourth, four times as
much. The result was that gramlneous
plants grew pretty we'll propOrtlonately to
the quantity of nitrogen supplied, while
leguminouS plants did lot follow the same
rule. Still the latter plants did not gene
rally flourish greatly in the pots to which
no nitrogen was supplied, only one plant
here and there developing luxuriantly. On
examination, it was found that the lnXu-
rianC plants had an abundant growth OfnO-
dulles on their roots, while the feeble ones
had none This gave rise to the impress
sion that organisms connected with the no
dulles might be the agency for the hxatIon
of free nitrogen for the nOurishment OF
plants, and Hellriegel instituted expert
ments to elucidate this point. To this end
he added to some of his pots small Quanti-
ties of a turbid extract OF a fertile soil, made
by shaking 81 given quantity OF 1t with five
times it's weight of distilled water. In
some eases this extract was applied as 1t
was thus obtained, and in others 1t was
sterilizpd, presumably by heat. In those
cases in which it was not SteriliZed there
was almost uniformly luxuriant growth and
abundant iOrmatiO OF root nOduleS in peas
vetcheS, and some other plants of the same
family but where the steIilizod soil oX-
tract was applied no such results followed.
This appeared to show pretty cOncIuSIVeIy
that organisms obtained from the fertile
soil were agents in forming root n0duleS
and fixing the nitrogen appropriated by
the aouriNhing plants from the atmosphere,
which was ihe only apparent source
whence they could have Obtained the con
,Ederable quantity essential to their de-
~Vciopment, and found in them when they
were matured. Blu the application Of tho
soil extract had no effect on lupins, and it
was thought that p ssihly the particular
variety Of oI ganism needed by p al.tS OF the
lupiu tribe had not been obtained from the
field whence the said extract was derived.
Accordingly, some extract was made front
soil taken from The field in which lupins
were growing we'll, and applied to pots i'll
which experiment. on lupinS were being
made. The results were then as S~atisfac-
tory with the lupins as they were with the
peas.
These r esuits we're deemed of such great
importanc e that Sir John Lawes determin-
ed to test them. Accordingly, in 1888, he
commenced experiments identical with
Hellriegel'S, and obtained Identical results,
except for disturbing Influences due, it is
supposed, to the sand used not being tree
from NITROGEN, and to the soil extract used
from luplns having been accidentally steri-
lized. Analysis of the peas showed that
there was at least twice as much nitrogen
in the above ground growth in pots to
which soil extract was applied aS in a pot
to which it was not added. Comparing the
total quantity of nitrogen iu the soil an'
PLANTS after the latter had matured with
the quantity in the soil and the seed, the
increase was thIeefOld even i'll a pot of linz
pureSand without soil extract, fivefold in
one pot to which soil extract was applied
and more than fOurfOld in another. These
increases cOnclusively prove that nitrogen
was obtained from the atmosphere,
In 1889 more extensive experiments were
carried on, care being taken to obtain
quartz sand sufficiently, if not absolutely,
sterilized. Peas, red clover, vetches, lu-
pins, and lucern were the plants grown,
and the results fully confirmed those of
1888, without the failure in the case of
lupinS due to the accidental circumstances
above alluded to. The complete results
have not yet been determined, some of the
plants, such As clover and lucern, having
been left to grow for a second season. But
Sir John Lawes, after duly considering the
results obtained SO far, says: "UpOn the
whole, then, the evidences at command
points to the conclusion that, in the case of
most If nor oil nf nnr lan1 M mons nSOro q