Rogue River courier. (Grants Pass, Or.) 1886-1927, 1910-12-02

named by bacterlologlsts Da'i''N'
amylovorus." For our purpose OIL
discussion we may call 1t the pear
blight bacillus, the pear blight germ
or the pear blight mierobe, all these
terms meaning practically the same
thing. These germs are among the
most minute OF living organisms anu
are az truly plants as trees, grasses
etc. However, they are very 10"
down in the scale Of the vegetable
kingdom, since the individual organ
ism consists OF single cell, wnicn
NAV be elliptical or rod-like Ii form
They multiply by lengthening littie
and then pinching In two. Ihis is
the only way in which they may IN
crease their numbers This procets
can take place within half an hour
mr. less. and this have proven py
observation In a hanging drop cur
ture under the microscope. Aitnousn
thew are extremely minute they may
be measured by means Of miscropical
annaratus. The standard OF measure
ment for these minute objects IS tne
m,cromillimeter, and a millimeter Is
about twenty-fifth part of an inch
The pear blight is from two-thirds
N three-fourths of micromillimeter
wide. and from one to one ana one
half micromillimeters long Wheh II
has reached It's mature stage. Al
another illustration showing their
minute size may say that II 2b,ooo
near blight germs were placed end
70 end they would scarcely measure
an inch in length. Curiously enough
the young germs are longer than the
older ones. When they are grow
ing rapidly their development In
length goes on more rapidly thar
their division. This germ forms nc
spores, and for this reason can no'
live over the dry season, as do the
germs OF anthrax which form spores
The pear blight germ is every sensi
tive to drying and, in fact, Is very
short-lived germ. The fact that i
does not form spores Is highly i'm
portant, as spore-forming bacterii
are capable OF living over In dus
which may be blown about by th'
winds. The germ dies rapidly In tn
blighted tissues, as soon as the tbs
sues have become fully killed. !
can not Withstand drying, usuall
dying within two weeks or so. IL
killed by exposure to direct sunshin
IN a very few minutes, usually nc
more than ten minutes unless pre-
tected by the bark or twigs. II raI
idly dies when II Is washed Into tn
soil, since II can no longer get IN
necessary food for It's existence an
multiplication. In fact, the pea
blight germs disappear and die ver
shortly after they are exuded
washed out by the rains from u
twigs and branches II also dies wne
the blighted bark dries up, II ca
only live along the advancing ma
gin OF the disease in the thick, flesf
bark or cambium which has been i
vaded by the bacteria, and whit
does not have time to dry out uni
the cool weather approaches. IT
thick bark OF the large lint
branches and root system renal
moist during a long period, especi'
ly in the winter. by this method, {
Importance OF which we will she
later, the germs are able to car
over, or live over, from one seas
to another. As n matter OF fact,
is only by this means that the pc
blight germ can live over during I
dormant period OF the trees 7
germs are killed by high tempe
ture, they are wholly destroyed VIII
subjected In LIQUID culture to
temperature OF 55 degrees centigrS
for ten minutes. They are who
uninjured, on the other hand, by G
degree OF cold. Temperatures OF
degrees Fahrenheit below zero hi
no effect whatever. They may
found 10 be frozen at this tempe
ture, but thaw out Immediately WI
plunged into warm water and so
with their activities uninjured c
retards their development but II
so prolongs their llie Like OF
vegetable organisms. cold storage
the effect OF prolonging life owe
long period OF time, In the lahC
tory the organism lives FOR relat
~ short time NJ room temperntu
while II the cultures nre put into
lcebox the berms may hve for MOI
providing the culture medium
not dry out,
In the lie cycle oi this &c
blossom blight may he consld,
MS the first step, .Nt least, this is
first step In It's lie cycle that Ia