The San Francisco call., 1897-07-01
Professor Bioletti on
Feed and Growth
of Plants.
Parasitic and Non-ParaSitiC
Diseases and Their
Remedies.
The Numerous Questions Asked oy
Farmers Show Their interest,"
in the Subject.

WRIGHTS, CAL, June 3d. Continuing
his course of lectures at the Hlghlahu
Grange Summer School OF Husbandry anu
Economies Tuesday F. T. Biolettl OF the
State University spoke in part as foilows'
Yesterday spoke of the plant cell. Today
/ will explain how the feeding and growth oI
The plan. takes place. Each OF the main paris
OF the plant has Its appropriate functlonsn. :.
The roots supply water and 1000 mater us u. .
found in the ground. The stems support the
leaves, carry the food to different parts OF tne
plant and store up reserve food. Ihe leaVes
take up and assimilate plant food from tne
air, and act as the lun gS OF the plans in
aspiration.
The food of the planti is thus derived from
two sources-the soil and the air. From me
soil, by means of its roots, are taken up all the
mineral elements, such as iron, potash, pnos'
phorus and nitrogen, needed for plant NE.
The tips of ,hs rootets are protected in thelr
passage through the ground by little thlmole-
like rootcaps. Behind these caps for about an
inch is the real absorbant surface OF the roof.
lets. This surface is Immensely REINFORCED
by tiny root hairs which grow out OF the outer
cells of the root. These are single cells; are
very delicate and absorb over their whole sur
face. They are continually dying, while new
ones grow out in new plaCes thus tapping dli-
ferent places in the soil where new 1000 male
rial may be found.
We will now inquire how these root hairs
absorb food. In the most thoroughly drained
soil there still remains some moisture. This
exists as thin film of water. closely investing
each particle OF the soil and held there by
cohesion. 1t is known as the microscopic
water of the soil, and is the medium by which
the plant hairs absorb their food. This film
dissolves the food elements found in the soil
and passes through the cell walls OF the plant
hairs by osmosis. Osmosis is the property
which solid substances have when dissolved
in a liquid of passing through an animal or
vegeta Dle memb brane, such as a cell wall IN
which the microscope can reveal no holeS or
pores. By this same process the food material
passes to all parts of the plant Another func-
tion of the root hairs Is the absorption OF
water,
From the air is taken up and assim Hated by
the leaves by far the larger part of the solid
n aterial liz the plant. All the starch, sugar,
eeilulose. cork and ligim, non-m neral food
ingredients of the plant, are made exclusively
from the carbonic acid gas of the atmosphere.
By means of a most important green bstance
called chlorophyll, which exists in the leaves,
the carbonic acid taken from the air Is con-
verted into starch. This. IN turn, Is con-
yerted into sugar, which, being easily soluble,
passes to different parts OF the plant, as 1t may
be needed by The process OF osmosis.
This afternoon Professor Bioietti lec-
tured on the causes of disease in plants.
By the number and variety of the ques-
they showed a wide practical experience
with plant diseases and an eagerness to
learn all they could from the lecturer
which would assist them 20 become good
plant doctors. Professor Bioletti said:
In brief, there are two general classes Of
disease in plants-parasitic and non parasitic,
or such as are caused by adverse conditions.
For practical purposes plant disease may be
looked upon as anything which, lplures the
market vasi e-5f fffe Dr5t' -
1t is usually the case that several CAUSES