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COLOUR AND PHOSPHORESCENCE
187
but if the tube is shaken further oxygen is admitted and
more
light is produced either as a glow or as a sudden
ash of light.
'
_
The oxy-luciferin can be deprived of the oxygen with
WhiCh
it has
united—Can
be
“
reduced ”
in
chemical
phraseology—and so converted
into
luciferin
again,
and can then be
used, when luciferase and oxygen are
present, to produce more light.
This process may ap—
parently also go on in nature, there being a continuous
'
'
change in the light organs of some animals from luciferin to
oxy—luciferin with the production of light and then back
,
again.
_
_
.
.
'
-
Certain bacteria are the
"
___
.
lowest form of life to pro—
_
'—°Ê
'.ä.
_. _
duce light.
They are re—
o
_
sponsible
for
the
light
‘
;
' -6—__:“
which appears on dead sh,
' -___: ‘ .
and they occasionally
O'; ;'
vade living animals giving
Î_ :=
_."'
_
'
them a luminous appear—
‘
9._‘_
.
ance.
According to a cer—
tain school of investigators
"‘;-'
‘
O
,
similar bacteria live within
the
luminous organs of
'
:"
"'
*
”many
animals
and
-are
.
'
'
'
the
cause
of
the
light
'
-
—
'
'
’
,
.
Produced thereOf the‘
'single-celled animals, the
,
,
.
greatly enlarged—
.
_
Protozoa, two especially,
.
_
'
Noct1‘luca
miliarz‘s
and _Pyro'cysn's noctiluca, have »ex—
'
ceptional powers‘ of phosphorescence (Fig. 38).
They
haVe no special organs for light production but contain
innumerable minute
granules
which
are
responsible
for. the luminescence.
The presence of these
animals— _
.