Waterbury evening Democrat. [volume] (Waterbury, Conn.) 1887-1895, 1890-05-26
4 STUDY OF SENSATION.
As Observed In the Lowest Forms
Of Life.

How the Words ..Irritabilty" and ''Diss
crimination" are Used to Bridge
Perplexing Probloms-sensitive
Plants and sponges-
II the green scum which accumulates
on roofing tiles and other exposed sur
faces be washed of and the water exam
ined under a microscope, 1t will be
found to TEEN with an organism either
entirely green or partly green and red.
This organism is known as the Prot0eoc-
Gus chat is, '.frst berry'D. and is one OF
the lowest and simplest forms OF true
plant-life. Its color indicates the pres
ence Of chlorophyll. and consequently
the power Of assimilating carbon from
tho carbonic acid OF the Atmosphere
one of the marks Of o true plant The
chief end Of the protococcus' life seems
to be to multiply, and this 1t accom-
plishes by dividing itself in pieces, each
piece forming a new individual, which
in turn divides up, to form further
crop. This method of reproduction 10
common in the lowest forms Of life, and
is known as fssion. or splitting of III
tie can be said about the inner J
the protococcus; but from the fact That
affected by conditions external to itself.
it m ay be assumed that these conditions
in some way or other inf uence the vi
tality of the organism. This is perhaps
rs 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, tho protococcus Is not
without touch Of romance. When
1~ir %rov wit
what they describe as red SHOWS" it is
nothing more nor less than the humble
but hardy protococcus flourishing 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 q
short step, and in some roadside ditch
or stagnant pool tho Amn6a finds a
homo. % ameba is o mere speck Of
ielly-looking matter, possessing neither
structure nor organization When this
simple matter Is found in connection
with life, whether plant or animal, it IL
known as protoplasm; and protoplasm is
found at the beginning Of every form OF
life, from the lowest plant to man him
self The ameba is ever changing Its
form (hence It's 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 tho surface of the am9ba, q
contraction OF the protoplasm takes
place. and an opening is made whore
tho organism struck. Soon the luckless
wanderer is engulfed in the body Of the
amBba and diges ted, so tar as it will
digest, to form new protoplasm. When
the ameba whose sense of hunger
never seems to fail, Is waxing too fat
for its own comfort, the protruding
fingers now and again drop Oh, and set
ting up on their own account IS new
individuals, repeat the life of the par.
emit. From the foregoing, 1t will DO
seen that the amoeba Is to a consider
able extent alive to what ia going on
around it. and were its structure un-
known, 1t might be affirmed that 1t
possessed tho special senses Of at least
touch and sight But it does not possess
the ghost of any sense organ. n The con-
traction Of the amoeba when struck by
another body resent les the con traction
Of muscular tissue under sudden irrita-
ton; but again, the ampba has no
tissue Of any kind. Tho parting with
pieces Of itself would seem to be de-
Lucrative act. Yet the am9ba 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-
scribe this particular form Of sensitive
ness Biologists appear to be agreed
that the contractile motion Of the
am1ba is sufficiently described under
tho torn '1rritability" or ''excitability,"
and the other movements are covered
by tho term discrimination" These
terms may to q certain extent be salts
factory; but their value will be better
understood when actions similar to that
Of the am9ba are considered in ono or
two Of the higher classes OF plants.
When tiny insect alights on certain
parts Of such plants as the sundew or
Venus fy-trap, o oontractile movement
is at once set up, which usually costs
| the luckless insect its life If irritated
few times by the point Of pencil or Q
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 sentative
TO the presence Of ammonia that It will
indicate its presence IN 9 solution so
dilute as to be beyond the recognition
Of the ordinary laboratory tests.
| From the behavior Of these plants it
might be surmised that they possess in
some measure the special senses Of
| touch and taste, and in tho 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 ay-trap shows neither
nerve nor muscle, far less any special
organs Of sense. As with the amoeba,
biologists write down the whole phe:
nomena as due to 'irritability" and
discrimination" These terms, no
doubt form very convenient bridge