The daily morning journal and courier. [volume] (New Haven, Conn.) 1894-1907, 1897-12-07
coLoRAT1oN OF BIRDS EGGS.

Some Ingenious Theories and Facts As
certained by biologists.
The why and wherefore of the colors
Of birds eggs has been a favorite theme
for speculation, from the quaint sur
Musings Of Sir Thomas Browne to the
solemn guesswork of Shufeldt, in his
ten biological laws explanatory OF the
variation in color of the shells of the
eggs in class AYES" Hewityoa piously
concludes that the beauty of these ele-
CANT and often exquisitelya. attractive
objects Is intended for the delight Of
human eyes; hence, as he says, eggs
simply white are put out Of sight in
holes! He also sees in the larger num-
Der of eggs laid by game birds a provi-
sion by benevolent providence for the
JOY Of the sportsman and the declara-
ton of the epicure Next comes man
who assures us that the colors of eggs
are due to the influence of their respec-
tive surroundings on the imagination of
the hen birds-the old story of Jacobs
little trick on Laban in the matter Of
young cattle. This school instances as
an example the red blotches prevalent
on the eggs of falcons regarded by it as
a record of the bloody experiences of
the parents but it does not explain
why the equally rapacious owls pro-
duce pure white eggs or the bloodthirs-
ty sk,ias and shrikes lay greenish ones.
I have often wondered why Mr.. Wal
lace never adduced BIRDS eggs as exam
Piles Of recognition colors, where, 1t
seems to me he might have made bet
ter case 1t is well-known fact that
birds occasionally lay in one another's
nests, and from what I know I am in
clined to think that this most often
happens between birds whose eggs are
plain or closely similar in markings, so
that a mistake might be excusable "as
between friends" The supposition that
the varied color1ngs are serviceable in
enabling the owners to recognize their
property would account for the white
ness of eggs laid in dark holes, where
no markings could easily be noticed,
and would give a reasonable explana-
ton OF the Individual variety, within
specific or tribal likeness, which char
acterizes all eggs. However near alike
they may seem to our eyes, doubtless a
mother-bird would be capable of select
ing her own out Of a hundred jumbled
together, so that, on the whole, this
theory seems to me much more tenable
than the other one.
1 do not believe, however that the
coloration Of the eggs of birds is truly
explained by either Of these hypothesis,
however much nature may utilize the
existing facts in the apparent direction
of either and even though / am willing
to admit freely that the influences Of
natural selection may have been, here
and there, instrumental in bringing out
this or that color or pattern. I believe,
on the contrary, that these colors and
patterns are a by result of pecu1iarities
of organization as intimate as is the
microscopic structure of the shell, and
that if natural selection is to get cred
it for it at all, it is only as far as pro-
tective colors in eggs may sometimes
have followed, as secondary, or acct
dentally correlated, "by product" the
tendency to produce protectively col
ored plumage. In other words, there
is a constant relation between the pig
ments that paint the feathers and those
that paint the egg; sometimes they are
suppressed altogether (but white birds
often lay highly colored eggs for in
stance, gulls); sometimes they produce
a similar effect, giving the eggs the
general tone of the mothers plumage,
as in the whippoorwill, shore-birds and
others; and sometimes they produce
upon eggs color effect entirely differ
ent from that of the parents plumage.
1t must not be forgotten that the tint
Of a pigment applied to an egg-shell
might be widely removed from that Of
the same pigment dyeing a feather; and
it is also necessary to remember that
many plumage colors are not pigmenta-
nv at all, but purely optical effects of
interference of the light reflected. Such
is the case with the FURNISHED back of
the turkey, the jeWel-like brilhance. Of