Lexington weekly intelligencer. (Lexington, Mo.) 1871-1887, 1880-11-20

entirely around the stem or branch
for several inches or even feet. Thu
upper portion of course ultimatel!
dies, unless, as may happen when tn
csmbium is not destroyed, a new
bark is formed underneath the deaf
one. The leaves are invaded by thu
DESTROYER, but tho sudden destruc
ton often witnessed is especially du'
to the girdling effects upon the liml
or trunk.
Tue progress Of the disease in thu
tissue Of the plant is always slow
The bacteria are not carried by thi
circulation in the fluids Of the tree
but gradually work their way BY
their own powers Of movement
through the imperforated walls o
the cells. These walls must present
an almost insurmountable barrier t.
their progress fTsm cell to cell. In
deed, the puzzle really ls how they
get through at all. In old wood tbs
cell walls become pierced with
minute pores, but no such thing ex.
ists iu the cells containing the stored
materials upon which the bacteris
live. The walls of such cells, though
psrmeabis by water, Lave no open.
ings which the highest powers Of the
microscope reveal, either before or
after the change produced by blight.
The thick cells Of the llber CAST or
inner fibrous layer are really proof
against the invasion by the bacteria.
Not infrequently q continuous layer
Of these cells separates the diseased
parts from those perfectly healthy.
1t may be that the progress OF the
nalady is thus checked in some
plants, while in others. with less
bast, it's course is uninterrupted.
LII the fermentation which occurs
of the starch, aud presumably OF
other carbonaceous materials, car
bonic acid, and hydrogen are formed.
This is very different from the results
of putrefaction or ordinary decay, aud
especially Indicates the agency of
bacteria, for the butyric fermentation
Is only known as q consequence of
their action.
Having now indicsted the changes
which take place in the still living
but infected cells, aud having found
All organism capable or producing
these changes, it remains to show
that this organism really does cause
the phenomena observed. The proof
is direct and, it is believed, conclu-
sive. 1t consists in artificially intro
ducing the bacteria into the healthy
bark Of living trees aud noting the
results. II I'M great number Of them
disease follows such incubation,
plainly spreading from the minute
puncture required, and if we are rsa-
sonably certain no other active agent
is thus introduced, cs the cunclu-
sion be avoided that the bacteria
which we see multiplying and
spreading from cell to cell do GER
talnly cause the observed changes,
aud thus the disease? This has been
done i'll the most careful manner.
and, in case Of the pear tree, has been
followed by disease in si1ty-three
per cent. of the inoculatiOnsl
In q few of the operations small
pieces of diseased bark were inserted
as Ill budding, but i'll most cases the
NEGOTIATIONS were performed by dip
ping a needle or sharp pointed knife
into the fluid (distilled water) con-
tanning many bacteria taken from
diseased trees, aud thrusting the
wetted instrument into healthy bark.
AS o counter check q clean needle
or knife was frequently inserted in a
similar manner in the bark.
In a row of ftty-fve pear trees,
three years old, certain evidence of
blight followed in s. per cent. Of the
NEGOTIATIONS with bacteria, in no
case from the puncture with a'clean
instrument, aud i'll IL case only
spontaneously. 1. e., without con-
scious Introduction by myself. Many
applications of bacteria to the uuin-
jured surface of the bark and the
leaves were without result.
Ineculatious in a similar way with
virus from the diseased pear in ap-
pie and ounce produced disease
Identical III every respect with that
in the pear. OF those in the apple 80
per cent. only were successful, while
100 per cent. Of the i~nOculatious i'll
ounce clearly communicated tue dis
ease. In the apple the percentage
successful was much reduced BY the
bark of portions more than one year
old. This may have been due to
temporary causes, not to uniform
conditions.
Here, then, is given the change
in the tissue, a living thing known
to produce such changes discovered,
and its active agency confirmed by
trial. Is it not more than probable
that the bacteria really cause the
disease.
The experiments above referred .c
(inoculstions) were made during
July and August, 1880, and papers
based upon these and previous inves-
legations were read by the author
before the recent meeting Of the
American Society of Mierescopists, at
Detroit, and of the American Asso-
citation for the advancement Of
science, at Boston. Examinations
have since confirmed Al expressed
opinion that the disease of the peach
tree, known az the "yellows," 10 also
due to bacteria. The peach tree
parasite, if such it may be called, is
less in transverse diameter. being
only l MN. (O.OOOOS4s inch) thick,
and has shorter calculations. The
length of what seems TO be the lyrical
form is 3.5 nm. (0.OOO12O2 inch). The
physiological effects seem to be very
nearly this same. The stored starch
is destroyed aud the cells left other
wise intact.