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The retina
at
back
of
our
eye, behind lens
and
cornea
is
constituted with billions
of
neurons.
The
neurons are nerve
cells
with
different
photoreceptors, which are divided
into two
major
categories according
to
their
shapes. The
first is
bacillary
shape
cells,
reacting only to light
and darkness,
while
the second is conic
shape,
also known
as
retinal cone, which
transmits message
of
colour
to our brain.
The
retinal
cones are
again divided
into
three
principal
types
according
to
their genetic functions, namely chromatic
red, green
and blue.
When
exposing
to light,
a mixtures
of
signals, through
photoreceptors of neurons with
a
series
of
chemical reactions
and
interactions, transmit
to
our
brain, composing
nature's greatest
moving
colour
picture in
our
mind.
When
a
birth
defect occurs, fre-
quently chromatic red in
DNA
or
RNA,
the person becomes
colour
blind
to
red
with
particular
or
total
inability
to
distinguish
this
colour.
Rarely,
there are also defects
in
other
chromatic
colours.
With
understanding
of
this
nature's mystery,
eugenicists
who
deal
with
improvement
(as
by
control of
human mating)
of
hereditary
qualities of persons, may
manage
to reduce such
defects
to
mini-
mum.
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