The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1899-08-09
POPULAR LECTURES
IN PHYSICAL SCIENCE.
VI. COLOR IN NATURE.
(Concluded.)
BY A. S. PACKARD, NJ. D., PHI. D.

OF hagen, Hopkins, Spuler, Urech, May
er and others that "a the colors of the
wings of moths and butterflies are due
IN some cases to pigments, in others to
optical effects, and sometimes to a
combination of the two; CD that pig
mental colorS are different shades of
yellow, red, deep brown, or rarely
white, green and pure black; go that
the white, yellow and red pigments of
the white or cabbage butterfly family
| (Pieridae), and possibly of other but
terfiles, are members of the uric-acid
group, and % that the red, yellow and
| white pigments, at least in the Pier
| ldae, are chemically nearly related,
while the black and brown pigments
differ markedly from them, and are of
unknown chemical relations. Then, as
shown by Mayer and others, in the de-
Velopment of color in the chrySaliS
white or yellow tints appear, these
growing darker as the insect develops,
black always being the last to appear
The present writer has noticed the
| same development of color in the pupa
| of humble bees. At first the hairs of
! the half-formed pupa are colorless or
whitish; shortly before the bee leaves
| its cell the hairs become darker, and
finally black, the yellow bands being
apparently the last to appear, unless
they are of near the primitive color,
and have through inheritance failed to
turn black, the original pale or yellow
ish hue surviving, but finally deepening
in tone just before the bee leaves its
cell and takes flight.
This interesting line of investigation
has been recently taken up by others
DR.. NJ. Baer confirms Hagen'S and Spu-
ler's view that the particular tint may
be due to the lines or dots or other
markings of the individual scales, or
to the combination of different scales.
He finds that scales showing optical
colors usually contain pigments in adj
dition, but this pigment does not pro-
duce any marked effect on the color,
though it may be concerned in its pro-
duction. Other apparently optical col
ors, such as emerald green, peacock
blue, violet, etc, are produced, he
claims, by the superposition of scales
containing pigment and scales giving
off optical colors. The exact physical
cause of the optical colorS he did not
ascertain. AS regards pigmental col
ors, Baer classifies them into two types:
Diffused and granular. Pigments of the
first type are diffused through the Chi
tin or substance of the scale, are usual
ly present in very small amount and
include the dark pigments most yellow,
orange and red pigments, except in the
Pieridae, and the white pigment (uric
acid of the Pieridae. Baer, as sum
M. lied by Newbigin in Natural Sci
ence" also, contrary to the results or
Hopkins, finds that some of the orange
and yellow pigments of the Pieridae are
diffuse and not granular. Granular
pigments occur exclusively in the Pier
idae and are yellow or red in color.
They color the scales in which they oc-
cur very deeply. Such scales are few
in number and almost without surface
ha
dark colored scales upon scales deeply
tinted by yellow granular pigment may,
as in Anthochans cardamineS, produce
a greenish tint
OF a good deal of interest is the order
of development of the colors. not only
in the individual, but in the entire
group of Iepidoptera. AS we have seen,
the earliest shades to appear in the
growing insect when in the chrysalls
stage are first colorlesS then yellowish
white or yellow, then orange ana or
ange red. the black tints being. the last
to appear. In a recent paper the Coun-
tess Maria Won Linden confirms this
view and finds that the black color in
butterflies is not due to a black pig
ment replacing the lighter ones. but to
the fact that darkly colored scales over
lie light ones. She also discovered that
optical colors, such as blue, appear
later than the dark tints and are only
exhihited bv scales which contain dark
pigment.
This leads us to the interesting ques-
ton of the development of color IN the
vast order of lepidopterous insects IN
general. Has there been a progressive
in color? OF what hue
were the earliest moths, and how did
the later moths and the butterflies ac-
duire their gorgeous styles of colora-
ton? These problems are difficult TO
answer, but the progressive develop |
ment of the colors of a single butterfly |
is most probably an epitome of the |
color development in the order to which |
it belongs.
1t is highly probable that the earliest, |
most primitive moths were, like the |
caddis flies, plain brownish: then some
with yellowish- brown or drab |
wings. We have caddis flies with spots |
and bars or stripes on their wings but !
they are very few in number The next
step was the evolution in moths of |
bright markings. The wings of certain |
forms became striped or barred. and |
this style being of utility prevailed.
Finally moths with spotted wings |
blue and other colors-appeared here |
and there in conspicuous places or the |
forewings became black and the hind
wings red or yellow, these colors being |
Interchangeable. Finally eye spots. like
those on the hind wings of the 10 moth
and many butterflies, were the latest |
to appear. Somehow moths and but
Lerfiies with bright spots became album
liant later in geological history, and the
presence of such markings evidently
had something to do with the preserva-
ton of the species. Hence a process of
natural selection, or, better. natural
preservation, arose, and nearly all these
yaily attired forms owe their COMPARE
i've immunity from the destructive at
.acks of birds and lizards to the special
of their markings.
In this connection the recent studies
n the field by Herr NJ. c. Piepers, who
mas spent much time butterfly hunting
n eastern Asia, resulted in valuable
He shows that in certain
If the eastern Pieridae the amount of
ed in the wings varies greatly: that |
ed and black vary inversely in
amount; that in dimorphic species the
male has usually more red and less
black than the female. and that where
he forewings contain much red, yellow
occurs on the hind wings. but when red
s present in small amount. yellow is
'eplaced by white. In brief. red and |
Yellow en- the one hand stand in anti
hesis to black and white on the other.
md red tends to predominant in the
males. He concludes that in this group
ed i'm itself, or in the forms of orange
II yellow, is the most primitive color in
he family that black and the dark
ints are more specialized and that as
hey develop the original red dimin-
shes in amount and fades to orange :
FELLOW and ultimately white but this