Emile Zola - "The Three Cities Trilogy: Paris, Vol. 1"

Annie Besant - "An Introduction to Yoga"

Baroness Orczy - "The League of the Scarlet Pimpernel"

Various - "Life at High Tide"

New Philadelphia Book Publisher Highlights Local Talent
Book and Publishing News from Publishers Newswire(tm)

Looking for Child to be on Cover of a New Book, 'The Model Child'
PHILADELPHIA, Pa. -- The Philadelphia literary world will celebrate the launch of two new players today, April 10th: Kay Square Press, a new publishing company focused on Philadelphia-area artists, their stories, and their art; and Kay Square's first release, 'With the Rich and Mighty: Emlen Etting of Philadelphia' (ISBN: 978-0-9815129-0-7), a critical biography by Kenneth C. Kaleta.

FlatSigned Press Alleges Don Imus Remarks Damage Legacy of President Gerald R. Ford
NEW YORK, N.Y. -- Nathan Yungerberg, an accomplished model scout and professional child photographer is launching a nation-wide casting call to find the cover model for his highly anticipated book release, 'The Model Child: A Parents Guide to the Child Modeling Industry' (ISBN: 978-0-9817018-0-6).

Books: On the Origin of Species

C >> Charles Darwin >> On the Origin of Species




In considering transitions of organs, it is so important to bear in
mind the probability of conversion from one function to another, that
I will give one more instance. Pedunculated cirripedes have two minute
folds of skin, called by me the ovigerous frena, which serve, through
the means of a sticky secretion, to retain the eggs until they are
hatched within the sack. These cirripedes have no branchiae, the whole
surface of the body and sack, including the small frena, serving for
respiration. The Balanidae or sessile cirripedes, on the other hand,
have no ovigerous frena, the eggs lying loose at the bottom of the
sack, in the well-enclosed shell; but they have large folded
branchiae. Now I think no one will dispute that the ovigerous frena in
the one family are strictly homologous with the branchiae of the other
family; indeed, they graduate into each other. Therefore I do not
doubt that little folds of skin, which originally served as ovigerous
frena, but which, likewise, very slightly aided the act of
respiration, have been gradually converted by natural selection into
branchiae, simply through an increase in their size and the
obliteration of their adhesive glands. If all pedunculated cirripedes
had become extinct, and they have already suffered far more extinction
than have sessile cirripedes, who would ever have imagined that the
branchiae in this latter family had originally existed as organs for
preventing the ova from being washed out of the sack?

Although we must be extremely cautious in concluding that any organ
could not possibly have been produced by successive transitional
gradations, yet, undoubtedly, grave cases of difficulty occur, some of
which will be discussed in my future work.

One of the gravest is that of neuter insects, which are often very
differently constructed from either the males or fertile females; but
this case will be treated of in the next chapter. The electric organs
of fishes offer another case of special difficulty; it is impossible
to conceive by what steps these wondrous organs have been produced;
but, as Owen and others have remarked, their intimate structure
closely resembles that of common muscle; and as it has lately been
shown that Rays have an organ closely analogous to the electric
apparatus, and yet do not, as Matteuchi asserts, discharge any
electricity, we must own that we are far too ignorant to argue that no
transition of any kind is possible.

The electric organs offer another and even more serious difficulty;
for they occur in only about a dozen fishes, of which several are
widely remote in their affinities. Generally when the same organ
appears in several members of the same class, especially if in members
having very different habits of life, we may attribute its presence to
inheritance from a common ancestor; and its absence in some of the
members to its loss through disuse or natural selection. But if the
electric organs had been inherited from one ancient progenitor thus
provided, we might have expected that all electric fishes would have
been specially related to each other. Nor does geology at all lead to
the belief that formerly most fishes had electric organs, which most
of their modified descendants have lost. The presence of luminous
organs in a few insects, belonging to different families and orders,
offers a parallel case of difficulty. Other cases could be given; for
instance in plants, the very curious contrivance of a mass of
pollen-grains, borne on a foot-stalk with a sticky gland at the end,
is the same in Orchis and Asclepias,--genera almost as remote as
possible amongst flowering plants. In all these cases of two very
distinct species furnished with apparently the same anomalous organ,
it should be observed that, although the general appearance and
function of the organ may be the same, yet some fundamental difference
can generally be detected. I am inclined to believe that in nearly the
same way as two men have sometimes independently hit on the very same
invention, so natural selection, working for the good of each being
and taking advantage of analogous variations, has sometimes modified
in very nearly the same manner two parts in two organic beings, which
owe but little of their structure in common to inheritance from the
same ancestor.

Although in many cases it is most difficult to conjecture by what
transitions an organ could have arrived at its present state; yet,
considering that the proportion of living and known forms to the
extinct and unknown is very small, I have been astonished how rarely
an organ can be named, towards which no transitional grade is known to
lead. The truth of this remark is indeed shown by that old canon in
natural history of "Natura non facit saltum." We meet with this
admission in the writings of almost every experienced naturalist; or,
as Milne Edwards has well expressed it, nature is prodigal in variety,
but niggard in innovation. Why, on the theory of Creation, should this
be so? Why should all the parts and organs of many independent beings,
each supposed to have been separately created for its proper place in
nature, be so invariably linked together by graduated steps? Why
should not Nature have taken a leap from structure to structure? On
the theory of natural selection, we can clearly understand why she
should not; for natural selection can act only by taking advantage of
slight successive variations; she can never take a leap, but must
advance by the shortest and slowest steps.

ORGANS OF LITTLE APPARENT IMPORTANCE.

As natural selection acts by life and death,--by the preservation of
individuals with any favourable variation, and by the destruction of
those with any unfavourable deviation of structure,--I have sometimes
felt much difficulty in understanding the origin of simple parts, of
which the importance does not seem sufficient to cause the
preservation of successively varying individuals. I have sometimes
felt as much difficulty, though of a very different kind, on this
head, as in the case of an organ as perfect and complex as the eye.

In the first place, we are much too ignorant in regard to the whole
economy of any one organic being, to say what slight modifications
would be of importance or not. In a former chapter I have given
instances of most trifling characters, such as the down on fruit and
the colour of the flesh, which, from determining the attacks of
insects or from being correlated with constitutional differences,
might assuredly be acted on by natural selection. The tail of the
giraffe looks like an artificially constructed fly-flapper; and it
seems at first incredible that this could have been adapted for its
present purpose by successive slight modifications, each better and
better, for so trifling an object as driving away flies; yet we should
pause before being too positive even in this case, for we know that
the distribution and existence of cattle and other animals in South
America absolutely depends on their power of resisting the attacks of
insects: so that individuals which could by any means defend
themselves from these small enemies, would be able to range into new
pastures and thus gain a great advantage. It is not that the larger
quadrupeds are actually destroyed (except in some rare cases) by the
flies, but they are incessantly harassed and their strength reduced,
so that they are more subject to disease, or not so well enabled in a
coming dearth to search for food, or to escape from beasts of prey.

Organs now of trifling importance have probably in some cases been of
high importance to an early progenitor, and, after having been slowly
perfected at a former period, have been transmitted in nearly the same
state, although now become of very slight use; and any actually
injurious deviations in their structure will always have been checked
by natural selection. Seeing how important an organ of locomotion the
tail is in most aquatic animals, its general presence and use for many
purposes in so many land animals, which in their lungs or modified
swim-bladders betray their aquatic origin, may perhaps be thus
accounted for. A well-developed tail having been formed in an aquatic
animal, it might subsequently come to be worked in for all sorts of
purposes, as a fly-flapper, an organ of prehension, or as an aid in
turning, as with the dog, though the aid must be slight, for the hare,
with hardly any tail, can double quickly enough.

In the second place, we may sometimes attribute importance to
characters which are really of very little importance, and which have
originated from quite secondary causes, independently of natural
selection. We should remember that climate, food, etc., probably have
some little direct influence on the organisation; that characters
reappear from the law of reversion; that correlation of growth will
have had a most important influence in modifying various structures;
and finally, that sexual selection will often have largely modified
the external characters of animals having a will, to give one male an
advantage in fighting with another or in charming the females.
Moreover when a modification of structure has primarily arisen from
the above or other unknown causes, it may at first have been of no
advantage to the species, but may subsequently have been taken
advantage of by the descendants of the species under new conditions of
life and with newly acquired habits.

To give a few instances to illustrate these latter remarks. If green
woodpeckers alone had existed, and we did not know that there were
many black and pied kinds, I dare say that we should have thought that
the green colour was a beautiful adaptation to hide this
tree-frequenting bird from its enemies; and consequently that it was a
character of importance and might have been acquired through natural
selection; as it is, I have no doubt that the colour is due to some
quite distinct cause, probably to sexual selection. A trailing bamboo
in the Malay Archipelago climbs the loftiest trees by the aid of
exquisitely constructed hooks clustered around the ends of the
branches, and this contrivance, no doubt, is of the highest service to
the plant; but as we see nearly similar hooks on many trees which are
not climbers, the hooks on the bamboo may have arisen from unknown
laws of growth, and have been subsequently taken advantage of by the
plant undergoing further modification and becoming a climber. The
naked skin on the head of a vulture is generally looked at as a direct
adaptation for wallowing in putridity; and so it may be, or it may
possibly be due to the direct action of putrid matter; but we should
be very cautious in drawing any such inference, when we see that the
skin on the head of the clean-feeding male turkey is likewise naked.
The sutures in the skulls of young mammals have been advanced as a
beautiful adaptation for aiding parturition, and no doubt they
facilitate, or may be indispensable for this act; but as sutures occur
in the skulls of young birds and reptiles, which have only to escape
from a broken egg, we may infer that this structure has arisen from
the laws of growth, and has been taken advantage of in the parturition
of the higher animals.

We are profoundly ignorant of the causes producing slight and
unimportant variations; and we are immediately made conscious of this
by reflecting on the differences in the breeds of our domesticated
animals in different countries,--more especially in the less civilized
countries where there has been but little artificial selection.
Careful observers are convinced that a damp climate affects the growth
of the hair, and that with the hair the horns are correlated. Mountain
breeds always differ from lowland breeds; and a mountainous country
would probably affect the hind limbs from exercising them more, and
possibly even the form of the pelvis; and then by the law of
homologous variation, the front limbs and even the head would probably
be affected. The shape, also, of the pelvis might affect by pressure
the shape of the head of the young in the womb. The laborious
breathing necessary in high regions would, we have some reason to
believe, increase the size of the chest; and again correlation would
come into play. Animals kept by savages in different countries often
have to struggle for their own subsistence, and would be exposed to a
certain extent to natural selection, and individuals with slightly
different constitutions would succeed best under different climates;
and there is reason to believe that constitution and colour are
correlated. A good observer, also, states that in cattle
susceptibility to the attacks of flies is correlated with colour, as
is the liability to be poisoned by certain plants; so that colour
would be thus subjected to the action of natural selection. But we are
far too ignorant to speculate on the relative importance of the
several known and unknown laws of variation; and I have here alluded
to them only to show that, if we are unable to account for the
characteristic differences of our domestic breeds, which nevertheless
we generally admit to have arisen through ordinary generation, we
ought not to lay too much stress on our ignorance of the precise cause
of the slight analogous differences between species. I might have
adduced for this same purpose the differences between the races of
man, which are so strongly marked; I may add that some little light
can apparently be thrown on the origin of these differences, chiefly
through sexual selection of a particular kind, but without here
entering on copious details my reasoning would appear frivolous.

The foregoing remarks lead me to say a few words on the protest lately
made by some naturalists, against the utilitarian doctrine that every
detail of structure has been produced for the good of its possessor.
They believe that very many structures have been created for beauty in
the eyes of man, or for mere variety. This doctrine, if true, would be
absolutely fatal to my theory. Yet I fully admit that many structures
are of no direct use to their possessors. Physical conditions probably
have had some little effect on structure, quite independently of any
good thus gained. Correlation of growth has no doubt played a most
important part, and a useful modification of one part will often have
entailed on other parts diversified changes of no direct use. So again
characters which formerly were useful, or which formerly had arisen
from correlation of growth, or from other unknown cause, may reappear
from the law of reversion, though now of no direct use. The effects of
sexual selection, when displayed in beauty to charm the females, can
be called useful only in rather a forced sense. But by far the most
important consideration is that the chief part of the organisation of
every being is simply due to inheritance; and consequently, though
each being assuredly is well fitted for its place in nature, many
structures now have no direct relation to the habits of life of each
species. Thus, we can hardly believe that the webbed feet of the
upland goose or of the frigate-bird are of special use to these birds;
we cannot believe that the same bones in the arm of the monkey, in the
fore leg of the horse, in the wing of the bat, and in the flipper of
the seal, are of special use to these animals. We may safely attribute
these structures to inheritance. But to the progenitor of the upland
goose and of the frigate-bird, webbed feet no doubt were as useful as
they now are to the most aquatic of existing birds. So we may believe
that the progenitor of the seal had not a flipper, but a foot with
five toes fitted for walking or grasping; and we may further venture
to believe that the several bones in the limbs of the monkey, horse,
and bat, which have been inherited from a common progenitor, were
formerly of more special use to that progenitor, or its progenitors,
than they now are to these animals having such widely diversified
habits. Therefore we may infer that these several bones might have
been acquired through natural selection, subjected formerly, as now,
to the several laws of inheritance, reversion, correlation of growth,
etc. Hence every detail of structure in every living creature (making
some little allowance for the direct action of physical conditions)
may be viewed, either as having been of special use to some ancestral
form, or as being now of special use to the descendants of this
form--either directly, or indirectly through the complex laws of
growth.

Natural selection cannot possibly produce any modification in any one
species exclusively for the good of another species; though throughout
nature one species incessantly takes advantage of, and profits by, the
structure of another. But natural selection can and does often produce
structures for the direct injury of other species, as we see in the
fang of the adder, and in the ovipositor of the ichneumon, by which
its eggs are deposited in the living bodies of other insects. If it
could be proved that any part of the structure of any one species had
been formed for the exclusive good of another species, it would
annihilate my theory, for such could not have been produced through
natural selection. Although many statements may be found in works on
natural history to this effect, I cannot find even one which seems to
me of any weight. It is admitted that the rattlesnake has a
poison-fang for its own defence and for the destruction of its prey;
but some authors suppose that at the same time this snake is furnished
with a rattle for its own injury, namely, to warn its prey to escape.
I would almost as soon believe that the cat curls the end of its tail
when preparing to spring, in order to warn the doomed mouse. But I
have not space here to enter on this and other such cases.

Natural selection will never produce in a being anything injurious to
itself, for natural selection acts solely by and for the good of each.
No organ will be formed, as Paley has remarked, for the purpose of
causing pain or for doing an injury to its possessor. If a fair
balance be struck between the good and evil caused by each part, each
will be found on the whole advantageous. After the lapse of time,
under changing conditions of life, if any part comes to be injurious,
it will be modified; or if it be not so, the being will become
extinct, as myriads have become extinct.

Natural selection tends only to make each organic being as perfect as,
or slightly more perfect than, the other inhabitants of the same
country with which it has to struggle for existence. And we see that
this is the degree of perfection attained under nature. The endemic
productions of New Zealand, for instance, are perfect one compared
with another; but they are now rapidly yielding before the advancing
legions of plants and animals introduced from Europe. Natural
selection will not produce absolute perfection, nor do we always meet,
as far as we can judge, with this high standard under nature. The
correction for the aberration of light is said, on high authority, not
to be perfect even in that most perfect organ, the eye. If our reason
leads us to admire with enthusiasm a multitude of inimitable
contrivances in nature, this same reason tells us, though we may
easily err on both sides, that some other contrivances are less
perfect. Can we consider the sting of the wasp or of the bee as
perfect, which, when used against many attacking animals, cannot be
withdrawn, owing to the backward serratures, and so inevitably causes
the death of the insect by tearing out its viscera?

If we look at the sting of the bee, as having originally existed in a
remote progenitor as a boring and serrated instrument, like that in so
many members of the same great order, and which has been modified but
not perfected for its present purpose, with the poison originally
adapted to cause galls subsequently intensified, we can perhaps
understand how it is that the use of the sting should so often cause
the insect's own death: for if on the whole the power of stinging be
useful to the community, it will fulfil all the requirements of
natural selection, though it may cause the death of some few members.
If we admire the truly wonderful power of scent by which the males of
many insects find their females, can we admire the production for this
single purpose of thousands of drones, which are utterly useless to
the community for any other end, and which are ultimately slaughtered
by their industrious and sterile sisters? It may be difficult, but we
ought to admire the savage instinctive hatred of the queen-bee, which
urges her instantly to destroy the young queens her daughters as soon
as born, or to perish herself in the combat; for undoubtedly this is
for the good of the community; and maternal love or maternal hatred,
though the latter fortunately is most rare, is all the same to the
inexorable principle of natural selection. If we admire the several
ingenious contrivances, by which the flowers of the orchis and of many
other plants are fertilised through insect agency, can we consider as
equally perfect the elaboration by our fir-trees of dense clouds of
pollen, in order that a few granules may be wafted by a chance breeze
on to the ovules?

SUMMARY OF CHAPTER.

We have in this chapter discussed some of the difficulties and
objections which may be urged against my theory. Many of them are very
grave; but I think that in the discussion light has been thrown on
several facts, which on the theory of independent acts of creation are
utterly obscure. We have seen that species at any one period are not
indefinitely variable, and are not linked together by a multitude of
intermediate gradations, partly because the process of natural
selection will always be very slow, and will act, at any one time,
only on a very few forms; and partly because the very process of
natural selection almost implies the continual supplanting and
extinction of preceding and intermediate gradations. Closely allied
species, now living on a continuous area, must often have been formed
when the area was not continuous, and when the conditions of life did
not insensibly graduate away from one part to another. When two
varieties are formed in two districts of a continuous area, an
intermediate variety will often be formed, fitted for an intermediate
zone; but from reasons assigned, the intermediate variety will usually
exist in lesser numbers than the two forms which it connects;
consequently the two latter, during the course of further
modification, from existing in greater numbers, will have a great
advantage over the less numerous intermediate variety, and will thus
generally succeed in supplanting and exterminating it.

We have seen in this chapter how cautious we should be in concluding
that the most different habits of life could not graduate into each
other; that a bat, for instance, could not have been formed by natural
selection from an animal which at first could only glide through the
air.

We have seen that a species may under new conditions of life change
its habits, or have diversified habits, with some habits very unlike
those of its nearest congeners. Hence we can understand, bearing in
mind that each organic being is trying to live wherever it can live,
how it has arisen that there are upland geese with webbed feet, ground
woodpeckers, diving thrushes, and petrels with the habits of auks.

Although the belief that an organ so perfect as the eye could have
been formed by natural selection, is more than enough to stagger any
one; yet in the case of any organ, if we know of a long series of
gradations in complexity, each good for its possessor, then, under
changing conditions of life, there is no logical impossibility in the
acquirement of any conceivable degree of perfection through natural
selection. In the cases in which we know of no intermediate or
transitional states, we should be very cautious in concluding that
none could have existed, for the homologies of many organs and their
intermediate states show that wonderful metamorphoses in function are
at least possible. For instance, a swim-bladder has apparently been
converted into an air-breathing lung. The same organ having performed
simultaneously very different functions, and then having been
specialised for one function; and two very distinct organs having
performed at the same time the same function, the one having been
perfected whilst aided by the other, must often have largely
facilitated transitions.

We are far too ignorant, in almost every case, to be enabled to assert
that any part or organ is so unimportant for the welfare of a species,
that modifications in its structure could not have been slowly
accumulated by means of natural selection. But we may confidently
believe that many modifications, wholly due to the laws of growth, and
at first in no way advantageous to a species, have been subsequently
taken advantage of by the still further modified descendants of this
species. We may, also, believe that a part formerly of high importance
has often been retained (as the tail of an aquatic animal by its
terrestrial descendants), though it has become of such small
importance that it could not, in its present state, have been acquired
by natural selection,--a power which acts solely by the preservation
of profitable variations in the struggle for life.