The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1867-08-23


plication Of the special-creation theory TO this
particular case.
The other two supposed explanations,
which may be shortly expressed as the theo-
ries of 'similar conditions and of "heredity,1
agree in making mimicry, where it exists, an
adventitious circumstance not necessarily con-
nected with the well-being OF the mimicking
species. But several of the most striking and
most constant facts which have been adduced
directly contradict both of these hypothesis.
The law that mimicry is confined to a few
groups only is one of these, for 'similar con-
ditions" must act more or less on all groups
in a limited region, and "heredity" must in
huence all groups related to each other in an
equal degree. Again, the general fact that
those species which mimic others are rare,
while those which are initiated are abundant,
is in no way explained by either of these the
ories, any more than is the frequent occur
renee of some palpable mode OF protection
in the initiated species. 'ReversiOn to an
ancestral type" no way explains why the imi-
tator and the initiated always inhabit the very
same district, whereas allied forms of every
degree of nearness and remoteness generally
inhabit different countries and often different
quarters of the glObe and neither it, nor
"similar conditions" will account for the
likeness between species of distinct groups
being superficial only-a disguise, not a true
resemblance; for the imitation of bark, of
leaves, of sticks, of dung; for the resemblance
between species in different orders, and even
different classes and sub Kingdoms; and finally,
for the graduated series of the phenomena,
beginning with general harmony and adap-
tation of tint in autumn and winter moths,
and in arctic and desert animals; and ending
with those complete cases of detailed mimi
cry which not only deceive predacious ami
mails, but puzzle the most experienced insect
collectors and the most learned entomologists.
But there is yet another series of phenom-
ena connected with this subject, which con-
sideraSly strengthens the view here adopted,
while it seems quite incompatible with either
of the other hypotheses; namely, the relation
of protective coloring and mimicry to the sex
ual differences of animals. 1t will be clear to
every one that if two animals which as regards
external conditions and hereditary descent
are exactly alike, yet differ remarkably in
cOlOration, one resembling protected species
and the other not, the resemblance that
exists in one only, can hardly be imputed
to the influence of external conditions or as
the effect of heredity. And if, further, it
can be proved that the one requires protection
more than the other, and that in several cases
it is that one which mimics the protected
species, while the one that least requires pro-
lection never does so, it will afford very strong
corroborative evidence that there is real con-
nection between the necessity for protection
and the phenomenon of mimicry. Now the
sexes of insects offer us a test of the nature
here indicated, and appear to furnish one of
the most conclusive arguments in favor of the
theory that the phenomena termed ''mimicry"
are produced by natural selection.
The comparative importance of the sexes
varies much in different classes of animals.
In the higher vertebrates, where the num-
Der of young produced at a birth is small
and the same individuals breed many years
in succession the preservation of both sexes
is almost equally important. In all the
numerous cases in which the male protects
the female and her offspring, or helps to
supply them with food, his importance in
the economy of nature is proportonally in
creased, though it is never, perhap, quite
equal to that of the female. In insects the
case is very different; they pair but once in
their lives, and the prolonged existence of
the male is in most cases quite unnecessary
for the continuance of the race. The fe-
male, however, must continue to exist
long enough to deposit her eggs in place
adapted for the development and growth of
the progeny. Hence there is a wide diffe-
renee in the need for protection in the two
sexes; and we should, therefore, expect to
find that in some cases the special protec-
tion given to the female was in the male
less in amount or altogether wanting. The
facts entirely confirm this expectation. In
Jne spectre insects (FnaSmlQte) IL Is often the
females alone that so strikingly resemble
leaves, while the males show only a rude
approximation. The male Diadema bolina
is very handsome and conspicuous butterfly
without sign of protective or initiative color
ing, while the female is entirely unlike her
partner and is one of the most wonderful
cases OF mimicry on record resembling most
accurately the common Danais chrysippus, in
whose company it is often found. So in several
species of South American Pieris, the males
are white and black, of similar type of color
ing to our own Cabbage butterflies, while
the females are rich yellow and buff, spotted
and marked so as to exactly resemble species
of Heliconide with which they associate in
the forest. In the Malay archipelago Mr.
Wallace found Diadema which had always
been considered a male insect on account of its
glossy metallic-blue tints, while its companion
OF sober brown was looked upon as the female.
He discovered, however, that the reverse is
the case, and that the rich and glossy colors of
the female are initiative and protective, since
they cause her exactly to resemble the COM
mon Euplra midamus of the same regions, q
species which has been already mentioned in
this article as mimicked by another butterfly,
Paplho paradoxa. In this case, and in that of
Dlademas bOlina, there is no difference in the
habits OF the two sexes, which fly in similar
localities; so that the influence of external
conditions" cannot be invoked here as it has
been IN the case of the South American Piers
pyrrha and allies, where the white males fire.
quent open sunny places, while the Helicsnia-
IKE females haunt the shades of the forest.
We may impute to the same general cause
the greater need of protection for the female,
nNUiTn TO laAFr 10, -