The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1899-08-02

! superficial layer of the feathers in its
passage to the eye; no blue or violet
pigments occur in feathers, and green
pigments are very rare" On the other
| hand, we are told that the beautiful
metallic tints of many birds are en-
! tirely the result of structure, owing
| their existence to a thin, transparent,
superficial layer which acts as a prism.
/ I'm such feathers the color changes
according to the relative position of the
bird and of the eye of the observer with
regard to the source of light" White,
and in some cases yellow, is produced
by the total reflection of light from the
spongy substance of the feather filed
with air. like white ice. There is no
such thing as white pigment. Parker
and Hasnells ZoologyD
In insects the conditions are some
what different, as the coloring matter
is lodged not only in the scales, but in
the skin or crust of the body. The pig
ment in most insects, as well as in the
lobster. is secreted in the deeper la,.er
of the skin, under the cuticle, and this
layer is called the hypodermis. When
the lobster casts its shell the soft hypo-
dermal layer consists of cells which are
filled with red and blue pigment mass
es. This cellular layer gives rise to the
outer cuticle, which thus derives it's
hue, red and blue, from the deeper
inner layer of color-secreting cells. In
most insects the cuticle is nearly color
less. or horn colored, or honey yellow
ish, in tint.
In insects the colors are both optical
and natural. Optical tints are due TO
the interference of light. in scales con-
tanning no pigment, but which are
marked with fine lines or are composed
of two layers. The beautiful colors of
butterflies reside in the scales. which
themselves are usually seen to be color
less when examined under the micro
scope.
Natural coiors in insects are both
dermal and hypodermal. The hypoder-
NAL colors. or pigments, are formed
from the waste products of the blood
not thrown off with the urinary secre-
tions. These colors tend to fade after
death, but when inclosed and preserved
in alright SacS. such as the scales and
hairs of butterflies and the wing covers
of beetles, the colors remain bright for
a Longer time, though finally fading
where dried specimens are exposed to
the light. Hypodermal colorS are light
er and brighter than dermal ones; they
are light clue and green of different
shades, and yellow to orange, and nu-
merous shades of these colors combined
with white the latter being due to the
presence of air. (Hagen.)
The colorS of insects can be changed
by exposure to different acids; also by
chan. of temperature. Madder-lake
and indigo blue can be produced arti-
ficially by the action OF acids on the
fat bodies of insects. 1t has been found
by experiments that pigments may be
dissolved out by chemical reagents and
subsequently restored by other agents.
Both Coste and Urech have proved that
reds. yellows, brown and black colOrs
in the scales of certain butterflies are
always due to pigments, and in few
cases greens. blues, violets, puppies and
whites are due to the presence of pig
ments in the scales themselves. Mr.. A.
CT. Mayer believes that the pigments of
lepidopterous insects are derived from
the blood of the chrysalis. The first
color to appear in the pupa or chrysalis
of the American silkworm. on which
he made his observations is dull yell
low ochre or drab; this is of the hue of
the blood when removed from the
chrysalis and exposed to the air.
Mayer has also artificially produced
several kinds of pigments from the
blood. which are similar in color to
various markings on the wings of the
image. or adult. He has also found
that chemical reagents have the same
effects on these manufactured prod
ucts as on similar pigments in the
wings of the living moth.
- r,.nlrrs lodi