The Ohio Democrat. (Logan, O. [Ohio]) 1886-1906, 1890-05-31
A STUDY OF SENSATION.
AS Observed in the Lowest Forms
OF Life.
How the words "Irritability" and 'Dis.
elimination" are Used to Bridge
Psrplexing Problcms-Sensitive
Plants and Sponnos.

If the green scum which accumulate
on roofing tiles and other exposed sur
faces be washed off and the water exam
ined under microscope, 1T Will b.
found to TEEN with an organism eithe
entirely green or partly green and red
This organism is known as the ProtOcoc
Gus that is, "frst berry,, and is one o
the lowest and simplest forms Of tru'
plant-life. Its color indicates the pres
ence of chlorophyll, and consequent,
the power of assimilating carbon from
the carbonic acid of the atmosphere
5nc of the marks of true plant Th'
chief end Of the protococcus' life seem
to be to multiply, and this it accom-
plishes by dividing itself in pieces, each
piece forming new individual, which
in turn divides up, to form further
crop This method of reproduction is
common in the loves forms of life, and
is known as fssioa, or splitting off Lit
tie can be said about the inner life oi
the protococcus; but from the fact that
the rapidity with which it mul tiplies is
affected by conditions external to ITSELF
it may be assumed that these conditions
in some way or other influence the vi
as much as can be said about sensation
in this lowly form of life; yet, while oc-
cupying position very near the bottom
of the scale, the protococcus is not
without touch of romance. When
Arctic or Alpine travellers meet with
what they describe as red SHOWS" 1t is
nothing more nor less than the humble
but hardy protococcus forrlshing and
multiplying on the surface of the virgin
snow.
From one of the lowest of plants to
one of the lowest of animals is but a
short step. and in some roadside ditch
or stagnant pool the AmGba finds a
home. The am9ba is a mere speck of
jelly-loobing matter, possessing neither
structure nor organization. When this
simple matter is found in connection
with life, whether plant or animal, it Is
known as protoplasm; and protoplasm is
found at the beginning of every form Of
life, from the lowest plant to man him
self The ammba is ever changing its
form (hence its name, which means
''change"), and by pushing out finger
looking processes is able to move about
through the water. 1t seems also to be
able in some mysterious way to avoid
collisions which might be disastrous to
itself. When smaller organism comes
against the surface of the ameba, a
contraction of the protoplasm takes
place, and an opening is made where
the organism struck. Soon the luckless
wanderer is engulfed in the body of the
ameba and diges ted, so far as it will
digest, to form new protoplasm. When
the amnba, whose sense of hunger
never seems to fail, is waxing too fat
for its own comfort, the protruding
fingers now and again drop of, and set
ting up on their own account as new
individuals, repeat the life of the par
ent. From the foregoing, it will be
seen that the amnba is to consider
able extent alive to what is going on
around it. and were its structure un-
known, it might be affirmed that it
possessed the special senses of at least
touch and sight But it does not possess
the ghost of any sense-organ. The con-
traction of the ameba when struck by
another body resembles the contraction
OF muscular tissue under sudden irrita-
tion: but again, the ameba has no
tissue of any kind. The parting with
pieces of itself would seem to be de-
Lucrative act. Yet the ameba has no
nerve or brain center where such delib-
GRAFTON could be carried on.
Notwithstanding all these negations,
the fact still remains that the ameba is
sensitive to outside conditions, and
some term or terms are required to de-
u. +. e..
ness. Biologists appear to be agreed
that the contractile motion of the
ameba is sufficiently described under
the term ''irritability" or ''eXcitability,
and the other movements are covered
by the term discrimination" These
terms may to a certain extent be salts
factory; but their value will be better
understood when actions similar to that
of the amCeba are considered in one or
two OF the higher classes of plants.
When a tiny insect alights on certain
parts of such plants as the sundew or
Venus hy-trap, a contractile movement
is at once set up, which usually costs
the lucklcss insect its life. If irritated
few times by the point of pencil or
sharp instrument, the plants seem to
discover the fraud, and cease to act.
Drops of rain falling with presumably
greater force than that exerted by the
alighting of an insect produce no effect.
The sundew, moreover, Is so sensitive
to the presence of ammonia that 1T will
indicate its presence In solution SO
dilute as to be beyond the recognition
of the ordinary laboratory tests.
From the behavior of these plants 1t
might be surmised that they possess in
some measure the special senses of
touch and taste, and in the case of the
sundew, also smell, to say nothing Of
an intelligence to make use of these
senses But the anatomy OF the sun
dew and Venus hy-rrap shows neither
nerve nor muscle, far less any special
organs of sense. As with the ameba,
biologists write down the whole phe-
nomena as due to ''irritability" and
discrimination These terms, no
doubt form very convenient bridge
for getting over such problems as the
movements of plants; but they evident
ly fall short Of explaining the phe-
nomena. fHft HttA ttst
The amnba being to all intents one
celled animal, 1t Is comparatively easy
TO understand that an act of irritation
should affect the whole mass; but in the
case OF the sensitive plants, where the
cells directly acted upon have TO pass
the irritation on to some millions Of
othar cells the satisfactorineRs of toe