The Washington herald., 1910-06-26

Most persons are familiar with vacci-
nation as a preventive OF the spread OF
smallpox. Well-reguIated communities
generally insist upon the school child
being able 10 show at least one scar made
by the process Of inserting cowpox into
the system 10 produce a varioloid that
makes the subject immune from small
pox over a period supposed TO be seven
years.
Many DO not believe in the practice
on the ground Of its inefficacy to ward
off smallpox. or on the ground that it is
dangerous. because of the possibility of
transmission OF tuberculosis or some
other contagicn. Recently something of
Juror has been raised by medical
men and TefoTmers against the so-called
cruelty and barbarism of compelling vac
cinstion by law as a condition pre-
liminary to a child entering the public
schools.
How COntagiOn Spreads.
Most persons are familiar. TO some ex-
tent, with incubation due to contact
with people suffering from measles. scar
let fever, and other transmlttable dis
eases. At least, they are familiar with
the fact that by such contact these dis
eases are contracted from one person TO
another. Still other illustrations are the
induction OF various toxins into the hui
man system TO stop the power OF dyph-
iberia or yellow fever.
But il has been left TO the Department
= -
incubation, so as TO include big fields.
growing crops. and the regeneration of
exhausted soils. In the case OF the
fields. crops. and soils. 1t is no such
delicate operation as scratching the skin
OF the human arm or the insertion of a
needle into the muscles OF the back.
Agricultural experts do not even treat
the corn stalks or the clover stems or
the branches Of the COW pea and the soy
bean. They go at the process on a much
more extensive scale than that by inn
premating the soil OF a whole field with
bacteria, and spreading broadcast pesti-
lence of microscopic life which attacks
the roots Of the growing plants and
makes two blades OF grass grow where
only one grew before.
Work on Roots of Plants.
II has DEGll lEdEltA titdL the Nd4U6 u
legumes as soil renovators is due 10 GER
tain bacteria which develop nodules upon
the roots of these plants, which have the
power Of rendering the free nitrogen OF
the air available for plant growth. This
Is another way Of saying that ii is neces-
sary 10 produce a disease in the growing
plant 10 make 1t useful. Without these
bacteria, legumes would exhaust and en-
danger the soil the same as any other
plant by taking the free nitrogen out OF
the soil. Through the disease engen-
dered BIZ the work OF the bacteria upon
the roots, the supply OF nitrogen comes
from the air 10 supply the plant growth.
and blowing It under the decay OF the
vegetable mold, enriches the soil, and
the bacteria upon the roots impregnate
the soil with millions OF their kind for
the next crop.
In some regions OF the country these
bacteria either do not exist or are few
and the department has found out a way
to multiply them; that Is 10 inoculate
the soil of a filed or a whole farm with
the bacteria so as 10 make It fruitful
The process is carried on by two methods
soil transfer. by which the bacteria are
carried IN the soil. and the use Of pure
Kind Produces Kind.
Another interesting fact worked out by
the department is that each species OF
legumes may be inoculated better from
that species than by using bacteria iso-
lated from some other species. AS ar
Illustration: the red clover bacteria that
will produce excellent results when ap-
v,ffa1 80 ancfhar Of roH afnr~rr mill
have little beneficial action when applied
to cow peas or soy beans.
The soil transfer method consists in
scattering over the new ground, at the
rate of 200 or 800 pounds TO the acre. sol
either from a healthy old field of the
same crop or from a new field OF the
same crop that shows abundance of no.
dulles on the roots. To facilitate even
scattering the inoculated soil should be
thoroughly mixed with several times IT'S
weight OF ordinary SOIL and may be
either drilled or broadcasteG.
If the soil is brcadcRsted il should be
narrowed in Immediately, and, If possible,
this should be done toward evening or on
a cloudy day, as bright sunshine is very
harmful TO the bacteria.
Pure Culture Method.
The method of incubation by pure Gull
lures depends TO a certain extent upon
the type of pure culture which may be
used. Generally speaking, however, a
bottle OF pure culture of the proper kind
Of bacteria is opened shortly before the
seed is to be planted, and the culture
mixed with the proper quantity of water
and applied to the seed in such a way
that all of the seed may be moistened
though not soaked. The seed should be
planted as SOON as practicable after this
treatment; that is, as soon as it is suffi-
GENTLY dry for convenient handling. Dry.
ing may be facilitated by adding dry
sifted earth, preferably from the field in
which the leguminous crop is to be
grown. 1t is undesirable to store In
oculated seed. as the nodule bacteria
often die out rapidly after the seed has
been treated with the pure cultures and
dried. Inoculated seed should never be
dried in the sun. 1t is also possible 70
thoroughly mix the pure culture with a
considerable quantity of soil. preferably
from the field where the legume is to
be sown. The treated soil can then be
distributed in the same manner as when
inoculating by the use of soil from an old
field.
The advantages of artificial cultures
lie in the greater ease OF their transpor-
tation and application as we'll as In the
absence Of the danger OF introducing
harmful weeds or plant diseases, al
though this method of incubation. es-
pecially in the case OF alfalfa, is less
certain than the soil transfer method.