COLOUR AND PHOSPHORESCENCE
181
roundings are the nightly changes of colour which occur-With
uniailing regularity.
Whatever “colour the prawns "may
'
_
have by
they all change to a “beautiful transparent
,
blue by night (Plate 66), the alterationin‘ colour taking” .
place quite quickly shortly after night£all.
f
5
!
'
Great numbers of minute “
pigmehtcells
”
scattered
over the surface of the body are' responsible for the colour”
-
of the Æsop prawn (Plate 68).
EaCh of these'cells consists
of a central bag running out from which are many ”ne
extensions.
Within the'central
there are three
-,
pigments, red, yellow, and blue, and the ”colour of the
_’
animal is controlled“ by the extentt0'wh‘ich these pigments
spread through the branches, -‘thus covering the
maximum area, or
withdraW’n into the centre where they
are
reduced in area to a minute point and so hardly affect
,
the general colour of the animal.
The three colours ”may be
‘
associated in different ways ; 't‘hus the red pigment alone
occupies the branches When the animal. is red, the green
colour is produced When the red pigment is withdraWn
into—the central bag and the yeHOW and blue pigments
together spread into the branches.
noëtu‘rnal blue
colour lis produced when-the red and yellow pigments are“
_
both withdrawn and. only the blue one extends into the
"
branches of the pigment cells.‘
'
.
‘
:
f
,
What is the mechanism which contrdls these remarkable ‘
'
and exact changes in colour ? - It'appeai*s that the pigment
cells are inuenced by the light which acts either by way
,
of“—the eyes or' directly” on the pigment cells.” Diñerént
light affects the'horm'o‘nes controlling the OW
pigment in “different Ways, “and ensùres that the colour
'
scheme produced shall tone with the background of the » -
animal..
The
supreme
importance of these elaborate "
,.
mechanisms ;f0r 0010ur' change to these little animals is
There can be no doubt that the protection given
_
181
roundings are the nightly changes of colour which occur-With
uniailing regularity.
Whatever “colour the prawns "may
'
_
have by
they all change to a “beautiful transparent
,
blue by night (Plate 66), the alterationin‘ colour taking” .
place quite quickly shortly after night£all.
f
5
!
'
Great numbers of minute “
pigmehtcells
”
scattered
over the surface of the body are' responsible for the colour”
-
of the Æsop prawn (Plate 68).
EaCh of these'cells consists
of a central bag running out from which are many ”ne
extensions.
Within the'central
there are three
-,
pigments, red, yellow, and blue, and the ”colour of the
_’
animal is controlled“ by the extentt0'wh‘ich these pigments
spread through the branches, -‘thus covering the
maximum area, or
withdraW’n into the centre where they
are
reduced in area to a minute point and so hardly affect
,
the general colour of the animal.
The three colours ”may be
‘
associated in different ways ; 't‘hus the red pigment alone
occupies the branches When the animal. is red, the green
colour is produced When the red pigment is withdraWn
into—the central bag and the yeHOW and blue pigments
together spread into the branches.
noëtu‘rnal blue
colour lis produced when-the red and yellow pigments are“
_
both withdrawn and. only the blue one extends into the
"
branches of the pigment cells.‘
'
.
‘
:
f
,
What is the mechanism which contrdls these remarkable ‘
'
and exact changes in colour ? - It'appeai*s that the pigment
cells are inuenced by the light which acts either by way
,
of“—the eyes or' directly” on the pigment cells.” Diñerént
light affects the'horm'o‘nes controlling the OW
pigment in “different Ways, “and ensùres that the colour
'
scheme produced shall tone with the background of the » -
animal..
The
supreme
importance of these elaborate "
,.
mechanisms ;f0r 0010ur' change to these little animals is
There can be no doubt that the protection given
_