The sun. [volume] (New York [N.Y.]) 1916-1920, 1919-05-04

Va hlOic vi ieSS UOAeS ne
tween which exist a certain number
of air spaces. A single cell Is shown
in figure and is seen to be composed
OF walls Of a strong supporting ma
terial (a), next to which lies a layer
of living protoplasm (b). the essential
substance which carries on all pro-
cesses necessary to life. Within this
lining there remains a space I'D filled
with cell-sap or blood" of the plant.
Embedded with the protoplasm may
be seen a number OF very important
bodies Up. p.) known as plastids. In
the bud and other green portions of
the plant these -plastids are filled with
the green pigment. chlorophyll, previ-
ously mentioned. Incidentally it Is
these green plastids or chloroplastids
which perform that most important
function for the plant, namely, that OF
storing the energy supply before men
toned.
The two pigments which give to
flowers their yellow color are carotin
and xanthophyll. Carotin is an orange
pigment; and, as its name implies, is
the cause of the brilliant color of car
tots. The latter. xanthophyll, Is
usually associated with carotin, and
they are both never to be found ex-
cept with the plastid bodies alone.
They are present. in addition to chloro.
phyll, in all green herbs and in grass,
and indeed 1t Is carotin derived from
this source that supplies cows with
the yellow colorng matter of cream,
butter and milk. Xanthophyll also
gives to the hen the yellow pigment
for its fat and to the egg its golden
yolk, as may be proved by depriving
poultry of grass or other food which
contains these pigments. The yellow
pigments are found. as has been said,
together with chlorophyll, in chloro-
plastids. These are present in the
green bud, which, during its develop
ment and expansion, loses the chloro-
phyll from the plastids, leaving the
corolla almost colorless, though in the
case OF yellow flowers carotin and
xanthophyll remain. These two pig
ments may become very concentrated,
as, for instance, In the orange red
margin of the corona OF the Poets
Narcussus (Ndrcissus poeticus), OF
which the color is due almost solely to
carotin.
The red blue pigments, or anthocy-
anins, are always dissolved in the cell
sap. (See Fig. d. They are never
present in the plastids, which only
contain the yellow pigments and with
which they must not be confused.
When we come to consider the various
factors which are able to modify a
color 1t will be seen how small a class
of pigments is sufficient to produce
every intermediate shade between blue
and red and even the palest pink or
lilac. 1t Is an anthocyanin which alike
colors the blue cornfower, the scarlet
geranium, the purple blackberry and
even the pink carnation and the mys-
| FERROUS blue periwinkle
g. Colors due to mixtures of pig
ments. The third class comprises
flowers In which two different pig
ments or two or more differently COL
ored pigments of the same sort are the
cause of the color. When, for instance,
plastid pigments occur together with
anthocyanins the result is usually a
| brown color, such as may be seen in
| the wallfiower (Cheirdnthus Cheiri),
as we'll as many shades OF scarlet, as
in the garden nasturtium (TropdcoIum
mdjus). Further, an anthocyanin of
one color may modify that of another.
For example. the lurid colors Of GER
tain larkspurs (Delphinium) are due
| lying side by side with cells containing
| a blue one.
4. White flowers. In this fourth
class are placed the large number of
| flowers which are devoid OF any pig
ment whatsoever. The snowy purity
of lilies and other white flowers is not
altogether due to a lack of pigment in
the cell or in the cell sap; for, as may
be seen from figure /, between one
cell and another are found numerous
interstices or intercellular spaces which
are filled with air. AS a rule the cell
walls which confine this air are
curved inward, and such convex sur
faces, especially when containing air,
possess the property of rejecting
back TO the observer white light In a
very high degree. The total effect of the
scattering and the reflection of light
| which takes place at these surfaces is
to cause a brilliant white appearance
as Of snow. Many other things besides
| flowers are white from the same cause.
The white Of feathers or OF ermine
and other white animals is due to the
numerous tiny air bells or chambers
| which they contain, and even the snCV-