12 
THE AUSTRALIAN GARDENER. 
March 1, 1905 
~ sre should rot believe the statement were it 
mot for convincing and irrefutable facts. 
Before explaining the discovery and man- 
wer of this extraordinary process of agri- 
cultural science, it might be well to review 
a few well-known facts in the life of plants. 
IMPORTANCE CE NITHCGEN. 
One vf the most important elements of 
the food of a plant is nitregen, which it 
‘absorbs from the soil mainly through its 
roots; successive crops of grain soon drain 
the soil of its plant food, and in process of 
time make the richest land pocr and worth- 
dess. 
A good farmer partly balances the drain 
pn his soil hy using plentiful quantities of 
gvenure ard fertiliser, and thus puts back 
mouch of the nitrogen whith bis crops re- 
amove. 
We send to Chili, thousands of miles 
auzy, for help, and at much expense import 
ficm her thousands of tons of costly nitrate, 
theugh we have aj] abcut us—in the air we 
hoe athe-exhaustless stores of fertiliser. 
Fiee nitrogen forms seven-tenths of the 
atmos} here. If we could tap and use this 
sea of nitrogen we could fertilise the whole 
énith and keep it rich; but it has been of 
mo use to us hitherto because we have had 
uo means of caj turing it and of putting it 
juto the ground. Its simplicity las baffled 
cus. Like the plenty that tormented Tanta- 
jus, it has ever eluded oui grasp. : 
A NITRCGEN FAMINE. 
We are taking the nitrogen from the soil 
so much faster than we can put it-back that 
scme persons have predicted a ‘‘nitrogen 
jamine” at no distant date, and have 
Juridly described the horrors that will fall 
spon us when the soil becomes so poverty- 
stricken that our crops of wheat and grain 
and rice will fail to feed the nations. While 
this view is, of course, partly imaginative 
and exaggerates the nearness of the danger, 
the fact remains that many areas in England 
and Europe and the Eastern United States, 
formerly fertile, are now unproductive be- 
‘cause the nitrogen in the soil has been ex- 
Fhausted. a 
But now man bas captured a tiny germ 
-Gnvisible to the naked eye, which can take 
from the boundless stores of nitrogen he has 
«oveted, avd put it into the earth for him. 
' Fiver since the time of Pliny, farmers 
Shaye noticed that, after a crop of peas, 
alfalfa, or any of the leguminous plants, a 
Meavier yield of wheat can be obtained ; 
thus bas arisen the old profitable rule of 
motation of erops. Ph 
But the reason why certain plants enrich 
the ground while others exhaust it remained 
mystery until an enquiring German dis- 
eovered some years ayo that peas, beans, - 
pte, obtained their nitrogen food not from 
the nitrates in the soil, but from the free 
supply in the air. 1 e also discovered that 
these plauts absorbed much more nitrogen 
than they could use, and left the suiplus in 
the soil—that is, beans, peas, alfalfa, clover — 
put back into the mother earth what corn 
‘and wheat and grains remove. The manner 
jn which they do this is unique, and another 
instance of the marvellous and mysterious 
laws by which the balance of nature is 
“maintained. 
THE BACTERIA NODULES, 
If one digs up a bealthy bean or clover 
plant and examines the roots, he will see a 
number of rounded bulbs, called nodules or 
tubercles, on the roots. At first sight he 
might imagine that the plant had a lot of 
sores over it, that it was diseised, or had 
been bitten by worms or insects. All legumes 
have these nodules or tubercles, varying in 
size from a pinhead to clusters as large as a 
good-sized potato. Scientists noticed that 
plants with good-sized nodules flourished, 
while plants without nodules or with very 
small ones looked starved and withered, aud 
they concluded that the nodules must have 
something to do with the vigor of the 
plants. On dissecting a bulb and examining 
under a microscope, it was found to be 
packed with bacteria. Further examina- 
tion showed that it and all nodules con- 
sisted of millions of bacteria, and that these 
bacteria were incessantly absorbing free 
nitrogen from the air and converting it into 
forms suitable for the plant’s digestion. 
NITROGEN-FIXING BACTERIA. 
For want of a better term, we will call 
the germs nitrogen-fixing bacteria. 
Careful examination of the earth showed 
that all.soils where these legumes grow con- 
tain these nitrogen -fixing bacteria in 
greater or less quantities; that these or- 
ganisms settle on the plants and form the 
colonies or tubercles on the roots If the 
soil contains none of these organisms to 
settle on the roots, the legumes will not 
grow at all. Each tubercle acts as a feeder 
to the plant. The more numerous and 
larger the tubercles the more prosperous is 
the plant. One might thus define a tubercle 
as a little factory where miliions of tireless, 
infinitesimal workers are separating the 
nitrogen in the air and converting it into 
plant food. A celebrated German, Pro- 
fessor Nobbe, of Tharandt, realised that if 
he could put into barren ground some of 
these organisms, or if he could artificially 
present the seeds with power to develop 
tubercles of themselves, he could make 
legumes grow in the most hopeless soil. 
THE FAILURE OF NITRAGIN. 
After much labor, he isolated the nitro- 
gen-fixing bacteria. He ~ succeeded in 
breeding and colonising the germs, and 
then proceeded to put them on the market. 
advertised them widely as able to make 
legumes grow in the pvorest soil. Naturally 
the announcement made a great sensation, 
and farmers from all quarters of the globe 
wrote him for sample bacteria. He sold 
different preparations for different ‘crops, 
putting them up in bottles and calling them 
Nitragin. But the bacteria did not work 
the miracles promised. Seeds inoculated 
with them failed to develop tubercles. A 
few persons, to be sure, obtained wonderful 
results, but the Vast majority of cases were 
complete failures The bacteria burned 
themselves out and disappeared without 
producing a single nodule on the plants. 
They lacked permanence. The nitragin was 
withdrawn from the market. 
These two men had done a great service 
to mankind: one had solved the problem of 
why certain plants enriched instead of 
drained the soil—he had isolated the micro- 
scopic agents, the myriads of organisms 
which carry back to mother earth what _ 
othérs had stolen; the other had shown 
that man could breed as many of these little 
helpers as he desired, but he had not been. 
able to give them permanence, so that man 
could get service from them At this point 
the inventive genius of an American, Dr.. 
George T. Moore, came to the rescue, and 
saved the discovery by giving it just the- 
practical value it had lacked. Dr. Moore is-. 
in charge of the Laboratory of Plant. 
Physiology of the Department of Agricul- 
ture, and a widely known practical botanist.. 
He had been watching Dr. Nobbe’s experi- 
ments, and had come to the conclusion that. 
Dr. Nobbe did not cultivate his nitrogen- 
fixing bacteria in the right way. Tha Ger- 
man’s method of rearing nis germ colonies 
resembled that of a rich father who gives. - 
his son everything he asks for without. 
making the boy work for anything, As a 
result, when the youth is thrown on his own 
resources he proves unable to earn his owa 
living, and collapses. Similarly, Dr. Nobbe, 
instead of developing the natural inclination 
and ability of his bacteria to hunt out 
nitrogen for themselves, dulled and 
destroyed this ability by giving them large 
quantities of nitrogen food, in what we 
might call predigested form ; he so satiated 
them with nitrogen that they lost their 
ability to hunt for it themselves, and when 
turned out of the laboratory were helpless. 
They soon consumed the store of nitrogen 
which they had received, but could not by 
themselves get any more. Their nitrogen- 
fixing ability was gone, and they perished, 
Dr. Moore decided not to dull the appe-- 
tite of the nitrogen-fixing bacteria by 
giving them all the nitrogen they wanted ; 
he thought he would whet their appetite— 
would strengthen. their nitrogen-fixing 
power, by exercise, by giving them in their 
food just enough nitrogen to make them 
want more and to make them strive to get 
more by their own efforts. By. following 
this principle of teeding he developed a 
permanent type of bacteria in his labora- 
tory, possessing five or ten times more 
power to flx nitrogen. than the original 
germs had possessed. The bacteria had 
gained strength, vigor, and self-reliance, 
aud, when turned out of the laboratory, 
prospered like all healthy bacteria. 
Legumes inoculated with the bacteria de- 
veloped great tubercles and grew to great 
size even in the poorest soil. 
The nitrogen-lixing power of the bacteria 
developed by Dr. Moore is so extraordinary 
that seeds soaked in the solution will sprout 
dnd produce luxurious plants in quartz sand 
which has been previously ignited to a red 
heat in order to drive out all nitrates. 
DISTRIBUTING MEDIUMS FoR SIE BACTERIA, 
Having secured a type of bacteria the 
nitrogen-fixing power of which was perma- 
nent, the next step was to obtain a simple 
means of distributing them to persons who 
desired to inoculate their land. Experi- 
ments showed that bacteria when grown 
upon nitrogen-free media will retain their 
high activity for a long time if carefully 
dried out and revived in a@ liquid medium. 
Dr. Moore also discovered that by using 
some absorbent, like cotton, a small piece 
of which will soak up millions of the or- 
ganisms, and then by allowing these cul- 
tures to become dry, the bacteria .can be 
seut to any part of the world and yet. 
arrive in perfect condition, 
