The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1897-10-30
LECTURE ON PLANTS.
Second OF the University Extension
Series, by John Nj. Coulter.

The second of the series of lectures by
John M Coulter. of the University of Chi
cago, under the auspices of the University
Extension, was given last night at the
First Baptist Church. Professor Coulters
topic was the Dependence of Plants Upon
Each Other" Professor Coulter said In
part:
plants are not scattered at haphazard
over the surface of the earth, but are or
ganiZed into definite associations or socie-
ties. Each society has its terms of admis-
sion, which may be discovered by examln-
ing the conditions of living. AS nature OF
soil and amount of water and many other
important factors may vary widely, the va
riouS plant societies. organized TO meet
certain combination Of these factors, are
very numerous. Among the plants in any
society we find a certain sort Of mutual de-
pendence. They divide the soil materials,
some climb upon the bodies of others III
order to reach suitable conditions. This
sort of Independence Is loose, but IT IS very
real Another form of mutual dependence,
much more intimate and necessary, mas
come to be known as symbiosis. 1t Will
be noted that the word means living TO-
gether," and the relationship is supposed to
be mutually helpful. In certain sense
parasite and it's host live together but this
haps the most notable case of symblosis lis
that found in the lichen. lichen is not
single plant, but two very different kinds
of plants, which have come to be very oe-
pendent upon each other. The lichen body
Is a composite, made up of an alga and a
fungus. The fungus part consists OF color-
less interviewer threads, which form the
wsrp and wool of the body. In the mesh
work of the body there lives green alga
which gives whatever of color the lichen
may possess. By virtue of its green colcr-
ing matter the alga Is able to make food
out OF water and carbon dioxide. Ths the
fungus is unable to do and so the alga
feeds it. Some have regarded the alga as
being held in slavery by the fungus. Lichens
grow in such exposed places however, that
oil w ar notwithstanding nIan1S
could not exist; but protected by the fun
gus mesh about them like damp sponge
and they are able to thrive The lichen,
therefore, has always been one of the most
important geological agents in the manu-
facture of humus on bare rocks: II the hrst
land surface was bare rocks, only some SUCH
composite organism as the lichen could
grow upon it. The fungus needs something
10 feed it, and the alga needs something 10
protect it. After lichens have grown on the
bare rock for a time, their decaying bodies
furnish humus in which higher plants can
begin to grow.
'sRoot Fungi.-Another interesting form Of
symbiosis lis found in connection with many
roots. notably those of such trees as the
cases a delicate thread-like fungus grows
in the soil and attaches itself to the roots.
The fungus helps the roots absorb soil ma
terial, and the roots feed the fungus with
organized food Not only does this root
| fungus help in absorption, but 1T breaks
I'D soil material and puts 1t into more
| favorable forms for absorption.
Root Tubercles.-The legume family, to
| which clover, peas and beans belong, mas
| been observed to develop upon its roots
| little tubercleS like very small potatoes. 1t
| has also long been known that clover can
| grow upon impoverished land and reclaim
| 1t. This power seems to be associated with
| the occurrence of these tubercles on the
| roots 1t is found that the tubercles swarm
| with certain kind of soil bacteria, which
| have the power of taking the free nitrogen
| OF the air and putting it into combinations
| that the plant can use. BY means of these
| bacteria, therefore, the clover can grow in
| soil impoverished in nitrogen foods, for it
| can obtain its nitrogen from the unfailing
| supply to be found in the air. The return
| the clover makes is to supply, In its tuber-
cles. a favorable place for the development
of the bacteria.
1.-THE great principle of symbiosis enters
into the living of plants and animals far
more extensively than was formerly inn
agined. In a large plant which produces
the green color, this color is only in the
surface cells. Only these cells, therefore,
can produce food. and the deeper cells are
dependent upon them, and at the same time
supply them with material necessary to
the making of food. Even in a single indi-
vidual living cell, prominently containing a
nucleus and cytoplaSm, these two organs
are possibly two different organisms, once
Independent, but now so dependent that
neither can exist without the other. Ex-
tending the view still further, we may say
that animals and plants together form a
great symbolic community.