THE INCOMPETENCY OF "NATURAL SELECTION" TO ACCOUNT FOR THE INCIPIENT STAGES
OF USEFUL STRUCTURES.
Mr. Darwin supposes that natural selection acts by slight
variations.--These must be useful at once.--Difficulties as to the
giraffe; as to mimicry; as to the heads of flat-fishes; as to the
origin and constancy of the vertebrate limbs; as to whalebone; as to
the young kangaroo; as to sea-urchins; as to certain processes of
metamorphosis; as to the mammary gland; as to certain ape characters;
as to the rattlesnake and cobra; as to the process of formation of the
eye and ear; as to the fully developed condition of the eye and ear; as
to the voice; as to shell-fish; as to orchids; as to ants.--The
necessity for the simultaneous modification of many
individuals.--Summary and conclusion.
"Natural Selection," simply and by itself, is potent to explain the
maintenance or the further extension and development of favourable
variations, which are at once sufficiently considerable to be useful from
the first to the individual possessing them. But Natural Selection utterly
fails to account for the conservation and development of the minute and
rudimentary beginnings, the slight and infinitesimal commencements of
structures, however useful those structures may afterwards become.
Now, it is distinctly enunciated by Mr. Darwin, that the spontaneous
variations upon which his theory depends are individually slight, minute,
and insensible. He says,[15] "Slight individual differences, however, {24}
suffice for the work, and are probably the sole differences which are
effective in the production of new species." And again, after mentioning
the frequent sudden appearances of domestic varieties, he speaks of "the
false belief as to the similarity of natural species in this respect."[16]
In his work on the "Origin of Species," he also observes, "Natural
Selection acts only by the preservation and accumulation of small inherited
modifications."[17] And "Natural Selection, if it be a true principle, will
banish the belief ... of any great and sudden modification in their
structure."[18] Finally, he adds, "If it could be demonstrated that any
complex organ existed, which could not possibly have been formed by
numerous, successive, slight modifications, my theory would absolutely
break down."[19]
Now the conservation of minute variations in many instances is, of course,
plain and intelligible enough; such, _e.g._, as those which tend to promote
the destructive faculties of beasts of prey on the one hand, or to
facilitate the flight or concealment of the animals pursued on the other;
provided always that these minute beginnings are of such a kind as really
to have a certain efficiency, however small, in favour of the conservation
of the individual possessing them; and also provided that no unfavourable
peculiarity in any other direction accompanies and neutralizes, in the
struggle for life, the minute favourable variation.
But some of the cases which have been brought forward, and which have met
with very general acceptance, seem less satisfactory when carefully
analysed than they at first appear to be. Amongst these we may mention "the
neck of the giraffe."
At first sight it would seem as though a better example in support of
"Natural Selection" could hardly have been chosen. Let the fact of the {25}
occurrence of occasional, severe droughts in the country which that animal
has inhabited be granted. In that case, when the ground vegetation has been
consumed, and the trees alone remain, it is plain that at such times only
those individuals (of what we assume to be the nascent giraffe species)
which were able to reach high up would be preserved, and would become the
parents of the following generation, some individuals of which would, of
course, inherit that high-reaching power which alone preserved their
parents. Only the high-reaching issue of these high-reaching individuals
would again, _cæteris paribus_, be preserved at the next drought, and would
again transmit to their offspring their still loftier stature; and so on,
from period to period, through æons of time, all the individuals tending to
revert to the ancient shorter type of body, being ruthlessly destroyed at
the occurrence of each drought.
(1.) But against this it may be said, in the first place, that the argument
proves too much; for, on this supposition, many species must have tended to
undergo a similar modification, and we ought to have at least several
forms, similar to the giraffe, developed from different Ungulata.[20] A
careful observer of animal life, who has long resided in South Africa,
explored the interior, and lived in the giraffe country, has assured the
Author that the giraffe has powers of locomotion and endurance fully equal
to those possessed by any of the other Ungulata of that continent. It would
seem, therefore, that some of these other Ungulates ought to have developed
in a similar manner as to the neck, under pain of being starved, when the
long neck of the giraffe was in its incipient stage.
To this criticism it has been objected that different kinds of animals are
preserved, in the struggle for life, in very different ways, and even {26}
that "high reaching" may be attained in more modes than one--as, for
example, by the trunk of the elephant. This is, indeed, true, but then none
of the African Ungulata[21] have, nor do they appear ever to have had, any
proboscis whatsoever; nor have they acquired such a development as to allow
them to rise on their hind limbs and graze on trees in a kangaroo-attitude,
nor a power of climbing, nor, as far as known, any other modification
tending to compensate for the comparative shortness of the neck. Again, it
may perhaps be said that leaf-eating forms are exceptional, and that
therefore the struggle to attain high branches would not affect many
Ungulates. But surely, when these severe droughts necessary for the theory
occur, the ground vegetation is supposed to be exhausted; and, indeed, the
giraffe is quite capable of feeding from off the ground. So that, in these
cases, the other Ungulata _must_ have taken to leaf eating or have starved,
and thus must have had any accidental long-necked varieties favoured and
preserved exactly as the long-necked varieties of the giraffe are supposed
to have been favoured and preserved.
The argument as to the different modes of preservation has been very well
put by Mr. Wallace,[22] in reply to the objection that "colour, being
dangerous, should not exist in nature." This objection appears similar to
mine; as I say that a giraffe neck, being needful, there should be many
animals with it, while the objector noticed by Mr. Wallace says, "a dull
colour being needful, all animals should be so coloured." And Mr. Wallace
shows in reply how porcupines, tortoises and mussels, very hard-coated
bombadier beetles, stinging insects and nauseous-tasted caterpillars, can
afford to be brilliant by the various means of active defence or passive
protection they possess, other than obscure colouration. He says "the {27}
attitudes of some insects may also protect them, as the habit of turning up
the tail by the harmless rove-beetles (Staphylinidæ) no doubt leads other
animals, besides children, to the belief that they can sting. The curious
attitude assumed by sphinx caterpillars is probably a safeguard, as well as
the blood-red tentacles which can suddenly be thrown out from the neck by
the caterpillars of all the true swallow-tailed butterflies."
But, because many different kinds of animals can elude the observation or
defy the attack of enemies in a great variety of ways, it by no means
follows that there are any similar number and variety of ways for attaining
vegetable food in a country where all such food, other than the lofty
branches of trees, has been for a time destroyed. In such a country we have
a number of vegetable-feeding Ungulates, all of which present minute
variations as to the length of the neck. If, as Mr. Darwin contends, the
natural selection of these favourable variations has alone lengthened the
neck of the giraffe by preserving it during droughts; similar variations,
in similarly-feeding forms, at the same times, ought similarly to have been
preserved and so lengthened the neck of some other Ungulates by similarly
preserving them during the same droughts.
(2.) It may be also objected, that the power of reaching upwards, acquired
by the lengthening of the neck and legs, must have necessitated a
considerable increase in the entire size and mass of the body (larger bones
requiring stronger and more voluminous muscles and tendons, and these again
necessitating larger nerves, more capacious blood-vessels, &c.), and it is
very problematical whether the disadvantages thence arising would not, in
times of scarcity, more than counterbalance the advantages.
For a considerable increase in the supply of food would be requisite on
account of this increase in size and mass, while at the same time there
would be a certain decrease in strength; for, as Mr. Herbert Spencer {28}
says,[23] "It is demonstrable that the excess of absorbed over expended
nutriment must, other things equal, become less as the size of an animal
becomes greater. In similarly-shaped bodies, the masses vary as the cubes
of the dimensions; whereas the strengths vary as the squares of the
dimensions.".... "Supposing a creature which a year ago was one foot high,
has now become two feet high, while it is unchanged in proportions and
structure--what are the necessary concomitant changes that have taken place
in it? It is eight times as heavy; that is to say, it has to resist eight
times the strain which gravitation puts on its structure; and in producing,
as well as in arresting, every one of its movements, it has to overcome
eight times the inertia. Meanwhile, the muscles and bones have severally
increased their contractile and resisting powers, in proportion to the
areas of their transverse sections; and hence are severally but four times
as strong as they were. Thus, while the creature has doubled in height, and
while its ability to overcome forces has quadrupled, the forces it has to
overcome have grown eight times as great. Hence, to raise its body through
a given space, its muscles have to be contracted with twice the intensity,
at a double cost of matter expended." Again, as to the cost at which
nutriment is distributed through the body, and effete matters removed from
it, "Each increment of growth being added at the periphery of an organism,
the force expended in the transfer of matter must increase in a rapid
progression--a progression more rapid than that of the mass."
There is yet another point. Vast as may have been the time during which the
process of evolution has continued, it is nevertheless not infinite. Yet,
as every kind, on the Darwinian hypothesis, varies slightly but
indefinitely in every organ and every part of every organ, how very
generally must favourable variations as to the length of the neck have {29}
been accompanied by some unfavourable variation in some other part,
neutralizing the action of the favourable one, the latter, moreover, only
taking effect during these periods of drought! How often must not
individuals, favoured by a slightly increased length of neck, have failed
to enjoy the elevated foliage which they had not strength or endurance to
attain; while other individuals, exceptionally robust, could struggle on
yet further till they arrived at vegetation within their reach.
However, allowing this example to pass, many other instances will be found
to present great difficulties.
Let us take the cases of mimicry amongst lepidoptera and other insects. Of
this subject Mr. Wallace has given a most interesting and complete
account,[24] showing in how many and strange instances this superficial
resemblance by one creature to some other quite distinct creature acts as a
safeguard to the first. One or two instances must here suffice. In South
America there is a family of butterflies, termed _Heliconidæ_, which are
very conspicuously coloured and slow in flight, and yet the individuals
abound in prodigious numbers, and take no precautions to conceal
themselves, even when at rest, during the night. Mr. Bates (the author of
the very interesting work "The Naturalist on the River Amazons," and the
discoverer of "Mimicry") found that these conspicuous butterflies had a
very strong and disagreeable odour; so much so that any one handling them
and squeezing them, as a collector must do, has his fingers stained and so
infected by the smell, as to require time and much trouble to remove it.
It is suggested that this unpleasant quality is the cause of the abundance
of the Heliconidæ; Mr. Bates and other observers reporting that they have
never seen them attacked by the birds, reptiles, or insects which prey upon
other lepidoptera.
Now it is a curious fact that very different South American butterflies{30}
put on, as it were, the exact dress of these offensive beauties and mimic
them even in their mode of flight.
In explaining the mode of action of this protecting resemblance Mr. Wallace
observes:[25] "Tropical insectivorous birds very frequently sit on dead
branches of a lofty tree, or on those which overhang forest paths, gazing
intently around, and darting off at intervals to seize an insect at a
considerable distance, with which they generally return to their station to
devour. If a bird began by capturing the slow-flying conspicuous
Heliconidæ, and found them always so disagreeable that it could not eat
them, it would after a very few trials leave off catching them at all; and
their whole appearance, form, colouring, and mode of flight is so peculiar,
that there can be little doubt birds would soon learn to distinguish them
at a long distance, and never waste any time in pursuit of them. Under
these circumstances, it is evident that any other butterfly of a group
which birds were accustomed to devour, would be almost equally well
protected by closely resembling a Heliconia externally, as if it acquired
also the disagreeable odour; always supposing that there were only a few of
them among a great number of Heliconias."
"The approach in colour and form to the Heliconidæ, however, would be at
the first a positive, though perhaps a slight, advantage; for although at
short distances this variety would be easily distinguished and devoured,
yet at a longer distance it might be mistaken for one of the uneatable
group, and so be passed by and gain another day's life, which might in many
cases be sufficient for it to lay a quantity of eggs and leave a numerous
progeny, many of which would inherit the peculiarity which had been the
safeguard of their parent."
[Illustration: LEAF BUTTERFLY IN FLIGHT AND REPOSE.
(_From Mr. Wallace's_ "_Malay Archipelago._")]
As a complete example of mimicry Mr. Wallace refers to a common Indian
butterfly. He says:[26] "But the most wonderful and undoubted case of
protective resemblance in a butterfly, which I have ever seen, is that {31}
of the common Indian _Kallima inachis_, and its Malayan ally, _Kallima
paralekta_. The upper surface of these is very striking and showy, as they
are of a large size, and are adorned with a broad band of rich orange {32}
on a deep bluish ground. The under side is very variable in colour, so that
out of fifty specimens no two can be found exactly alike, but every one of
them will be of some shade of ash, or brown, or ochre, such as are found
among dead, dry, or decaying leaves. The apex of the upper wings is
produced into an acute point, a very common form in the leaves of tropical
shrubs and trees, and the lower wings are also produced into a short narrow
tail. Between these two points runs a dark curved line exactly representing
the midrib of a leaf, and from this radiate on each side a few oblique
lines, which serve to indicate the lateral veins of a leaf. These marks are
more clearly seen on the outer portion of the base of the wings, and on the
inner side towards the middle and apex, and it is very curious to observe
how the usual marginal and transverse striæ of the group are here modified
and strengthened so as to become adapted for an imitation of the venation
of a leaf." ... "But this resemblance, close as it is, would be of little
use if the habits of the insect did not accord with it. If the butterfly
sat upon leaves or upon flowers, or opened its wings so as to expose the
upper surface, or exposed and moved its head and antennæ as many other
butterflies do, its disguise would be of little avail. We might be sure,
however, from the analogy of many other cases, that the habits of the
insect are such as still further to aid its deceptive garb; but we are not
obliged to make any such supposition, since I myself had the good fortune
to observe scores of _Kallima paralekta_, in Sumatra, and to capture many
of them, and can vouch for the accuracy of the following details. These
butterflies frequent dry forests, and fly very swiftly. They were seen to
settle on a flower or a green leaf, but were many times lost sight of in a
bush or tree of dead leaves. On such occasions they were generally searched
for in vain, for while gazing intently at the very spot where one had
disappeared, it would often suddenly dart out, and again vanish twenty or
fifty yards further on. On one or two occasions the insect was detected{33}
reposing, and it could then be seen how completely it assimilates itself to
the surrounding leaves. It sits on a nearly upright twig, the wings fitting
closely back to back, concealing the antennæ and head, which are drawn up
between their bases. The little tails of the hind wing touch the branch,
and form a perfect stalk to the leaf, which is supported in its place by
the claws of the middle pair of feet, which are slender and inconspicuous.
The irregular outline of the wings gives exactly the perspective effect of
a shrivelled leaf. We thus have size, colour, form, markings, and habits,
all combining together to produce a disguise which may be said to be
absolutely perfect; and the protection which it affords is sufficiently
indicated by the abundance of the individuals that possess it."
Beetles also imitate bees and wasps, as do some Lepidoptera; and objects
the most bizarre and unexpected are simulated, such as dung and drops of
dew. Some insects, called bamboo and walking-stick insects, have a most
remarkable resemblance to pieces of bamboo, to twigs and branches. Of these
latter insects Mr. Wallace says:[27] "Some of these are a foot long and as
thick as one's finger, and their whole colouring, form, rugosity, and the
arrangement of the head, legs, and antennæ, are such as to render them
absolutely identical in appearance with dry sticks. They hang loosely about
shrubs in the forest, and have the extraordinary habit of stretching out
their legs unsymmetrically, so as to render the deception more complete."
Now let us suppose that the ancestors of these various animals were all
destitute of the very special protections they at present possess, as on
the Darwinian hypothesis we must do. Let it also be conceded that small
deviations from the antecedent colouring or form would tend to make some of
their ancestors escape destruction by causing them more or less frequently
to be passed over, or mistaken by their persecutors. Yet the deviation {34}
must, as the event has shown, in each case be in some definite direction,
whether it be towards some other animal or plant, or towards some dead or
inorganic matter. But as, according to Mr. Darwin's theory, there is a
constant tendency to indefinite variation, and as the minute incipient
variations will be in _all directions_, they must tend to neutralize each
other, and at first to form such unstable modifications that it is
difficult, if not impossible, to see how such indefinite oscillations of
infinitesimal beginnings can ever build up a sufficiently appreciable
resemblance to a leaf, bamboo, or other object, for "Natural Selection" to
seize upon and perpetuate. This difficulty is augmented when we consider--a
point to be dwelt upon hereafter--how necessary it is that many individuals
should be similarly modified simultaneously. This has been insisted on in
an able article in the _North British Review_ for June 1867, p. 286, and
the consideration of the article has occasioned Mr. Darwin to make an
important modification in his views.[28]
In these cases of mimicry it seems difficult indeed to imagine a reason why
variations tending in an _infinitesimal degree_ in any special direction
should be preserved. All variations would be preserved which tended to
obscure the perception of an animal by its enemies, whatever direction
those variations might take, and the common preservation of conflicting
tendencies would greatly favour their mutual neutralization and
obliteration if we may rely on the many cases recently brought forward by
Mr. Darwin with regard to domestic animals.
[Illustration: THE WALKING-LEAF INSECT.]
Mr. Darwin explains the imitation of some species by others more or less
nearly allied to it, by the common origin of both the mimic and the
mimicked species, and the consequent possession by both (according to the
theory of "Pangenesis") of gemmules tending to reproduce ancestral
characters, which characters the mimic must be assumed first to have {35}
lost and then to have recovered. Mr. Darwin says,[29] "Varieties of one
species frequently mimic distinct species, a fact in perfect harmony with
the foregoing cases, and explicable _only on the theory of descent_." But
this at the best is but a partial and very incomplete explanation. It is
one, moreover, which Mr. Wallace does not accept.[30] It is very
incomplete, because it has no bearing on some of the most striking cases,
and of course Mr. Darwin does not pretend that it has. We should have to go
back far indeed to reach the common ancestor of the mimicking {36}
walking-leaf insect and the real leaf it mimics, or the original progenitor
of both the bamboo insect and the bamboo itself. As these last most
remarkable cases have certainly nothing to do with heredity,[31] it is
unwarrantable to make use of that explanation for other protective
resemblances, seeing that its inapplicability, in certain instances, is so
manifest.
Again, at the other end of the process it is as difficult to account for
the last touches of perfection in the mimicry. Some insects which imitate
leaves extend the imitation even to the very injuries on those leaves made
by the attacks of insects or of fungi. Thus, speaking of one of the
walking-stick insects, Mr. Wallace says:[32] "One of these creatures
obtained by myself in Borneo (_Ceroxylus laceratus_) was covered over with
foliaceous excrescences of a clear olive-green colour, so as exactly to
resemble a stick grown over by a creeping moss or jungermannia. The Dyak
who brought it me assured me it was grown over with moss although alive,
and it was only after a most minute examination that I could convince
myself it was not so." Again, as to the leaf butterfly, he says:[33] "We
come to a still more extraordinary part of the imitation, for we find
representations of leaves in every stage of decay, variously blotched, and
mildewed, and pierced with holes, and in many cases irregularly covered
with powdery black dots, gathered into patches and spots, so closely
resembling the various kinds of minute fungi that grow on dead leaves, that
it is impossible to avoid thinking at first sight that the butterflies
themselves have been attacked by real fungi."
Here imitation has attained a development which seems utterly beyond the
power of the mere "survival of the fittest" to produce. How this double
mimicry can importantly aid in the struggle for life seems puzzling indeed,
but much more so how the first faint beginnings of the imitation of {37}
such injuries in the leaf can be developed in the animal into such a
complete representation of them--_a fortiori_ how simultaneous and similar
first beginnings of imitations of such injuries could ever have been
developed in several individuals, out of utterly indifferent and
indeterminate infinitesimal variations in all conceivable directions.
[Illustration: PLEURONECTIDÆ, WITH THE PECULIARLY PLACED EYE IN DIFFERENT
POSITIONS.
(_From Dr. Traquair's paper in the "Transactions of the Linnean Society,
1865."_)]
Another instance which may be cited is the asymmetrical condition of the
heads of the flat-fishes (Pleuronectidæ), such as the sole, the flounder,
the brill, the turbot, &c. In all these fishes the two eyes, which in the
young are situated as usual one on each side, come to be placed, in the
adult, both on the same side of the head. If this condition had appeared at
once, if in the hypothetically fortunate common ancestor of these fishes an
eye had suddenly become thus transferred, then the perpetuation of such a
transformation by the action of "Natural Selection" is conceivable enough.
Such sudden changes, however, are not those favoured by the Darwinian
theory, and indeed the accidental occurrence of such a spontaneous
transformation is hardly conceivable. But if this is not so, if the transit
was gradual, then how such transit of one eye a minute fraction of the {38}
journey towards the other side of the head could benefit the individual is
indeed far from clear. It seems, even, that such an incipient
transformation must rather have been injurious. Another point with regard
to these flat-fishes is that they appear to be in all probability of recent
origin--_i.e._ geologically speaking. There is, of course, no great stress
to be laid on the mere absence of their remains from the secondary strata,
nevertheless that absence is noteworthy, seeing that existing fish
families, _e.g._ sharks (Squalidæ), have been found abundantly even down so
far as the carboniferous rocks, and traces of them in the Upper Silurian.
Another difficulty seems to be the first formation of the limbs of the
higher animals. The lowest Vertebrata[34] are perfectly limbless, and if,
as most Darwinians would probably assume, the primeval vertebrate creature
was also apodal, how are the preservation and development of the first
rudiments of limbs to be accounted for--such rudiments being, on the
hypothesis in question, infinitesimal and functionless?
In reply to this it has been suggested that a mere flattening of the end of
the body has been useful, such, _e.g._, as we see in sea-snakes,[35] which
may be the rudiment of a tail formed strictly to aid in swimming. Also that
a mere _roughness_ of the skin might be useful to a swimming animal by
holding the water better, that thus minute processes might be selected and
preserved, and that, in the same way, these might be gradually increased
into limbs. But it is, to say the least, very questionable whether a
roughness of the skin, or minute processes, would be useful to a {39}
swimming animal; the motion of which they would as much impede as aid,
unless they were at once capable of a suitable and appropriate action,
which is against the hypothesis. Again, the change from mere indefinite and
accidental processes to two regular pairs of symmetrical limbs, as the
result of merely fortuitous, favouring variations, is a step the
feasibility of which hardly commends itself to the reason, seeing the very
different positions assumed by the ventral fins in different fishes. If the
above suggestion made in opposition to the views here asserted be true,
then the general constancy of position of the limbs of vertebrata may be
considered as due to the position assumed by the primitive rugosities from
which those limbs were generated. Clearly only two pairs of rugosities were
so preserved and developed, and all limbs (on this view) are descendants of
the same two pairs, as all have so similar a fundamental structure. Yet we
find in many fishes the pair of fins, which correspond to the hinder limbs
of other animals, placed so far forwards as to be either on the same level
with, or actually in front of, the normally anterior pair of limbs; and
such fishes are from this circumstance called "thoracic," or "jugular"
fishes respectively, as the weaver fishes and the cod. This is a wonderful
contrast to the fixity of position of vertebrate limbs generally. If then
such a change can have taken place in the comparatively short time occupied
by the evolution of these special fish forms, we might certainly expect
other and far more bizarre structures would (did not some law forbid) have
been developed, from other rugosities, in the manifold exigencies of the
multitudinous organisms which must (on the Darwinian hypothesis) have been
gradually evolved during the enormous period intervening between the first
appearance of vertebrate life and the present day. Yet, with these
exceptions, the position of the limbs is constant from the lower fishes up
to man, there being always an anterior pectoral pair placed in front of a
posterior or pelvic pair when both are present, and in no single {40}
instance are there more than these two pairs.
[Illustration: MOUTH OF A WHALE.]
The development of whalebone (baleen) in the mouth of the whale is another
difficulty. A whale's mouth is furnished with very numerous horny plates,
which hang down from the palate along each side of the mouth. They thus
form two longitudinal series, each plate of which is placed transversely to
the long axis of the body, and all are very close together. On depressing
the lower lip the free outer edges of these plates come into view. Their
inner edges are furnished with numerous coarse hair-like processes,
consisting of some of the constituent fibres of the horny plates--which, as
it were, fray out--and the mouth is thus lined, except below, by a network
of countless fibres formed by the inner edges of the two series of plates.
This network acts as a sort of sieve. When the whale feeds it takes {41}
into its mouth a great gulp of water, which it drives out again through the
intervals of the horny plates of baleen, the fluid thus traversing the
sieve of horny fibres, which retains the minute creatures on which these
marine monsters subsist. Now it is obvious, that if this baleen had once
attained such a size and development as to be at all useful, then its
preservation and augmentation within serviceable limits, would be promoted
by "Natural Selection" alone. But how to obtain the beginning of such
useful development? There are indeed certain animals of exclusively aquatic
habits (the dugong and manatee) which also possess more or less horn on the
palate, and at first sight this might be taken as a mitigation of the
difficulty; but it is not so, and the fact does not help us one step
further along the road: for, in the first place, these latter animals
differ so importantly in structure from whales and porpoises that they form
an altogether distinct order, and cannot be thought to approximate to the
whale's progenitors. They are vegetarians, the whales feed on animals; the
former never have the ribs articulated in the mode in which they are in
some of the latter; the former have pectoral mammæ, and the latter are {42}
provided with two inguinal mammary glands, and have the nostrils enlarged
into blowers, which the former have not. The former thus constitute the
order Sirenia, while the latter belong to the Cetacea. In the second place,
the horny matter on the palates of the dugong and manatee has not, even
initially, that "strainer" action, which is the characteristic function of
the Cetacean "baleen."
[Illustration: FOUR PLATES OF BALEEN SEEN OBLIQUELY FROM WITHIN.]
[Illustration: DUGONG.]
There is another very curious structure, the origin or the disappearance of
which it seems impossible to account for on the hypothesis of minute
indefinite variations. It is that of the mouth of the young kangaroo. In
all mammals, as in ourselves, the air-passage from the lungs opens in the
floor of the mouth behind the tongue, and in front of the opening of the
gullet, so that each particle of food as it is swallowed passes over the
opening, but is prevented from falling into it (and thus causing death from
choking) by the action of a small cartilaginous shield (the epiglottis),
which at the right moment bends back and protects the orifice. Now the
kangaroo is born in such an exceedingly imperfect and undeveloped
condition, that it is quite unable to suck. The mother therefore places the
minute blind and naked young upon the nipple, and then injects milk into it
by means of a special muscular envelope of the mammary gland. Did no
special provision exist, the young one must infallibly be choked by the
intrusion of the milk into the windpipe. But there _is_ a special
provision. The larynx is so elongated that it rises up into the posterior
end of the nasal passage, and is thus enabled to give free entrance to the
air for the lungs, while the milk passes harmlessly on each side of this
elongated larynx, and so safely attains the gullet behind it.
Now, on the Darwinian hypothesis, either all mammals descended from
marsupial progenitors, or else the marsupials, sprung from animals having
in most respects the ordinary mammalian structure. [Page 43]
On the first alternative, how did "Natural Selection" remove this (at least
perfectly innocent and harmless) structure in almost all other mammals,
and, having done so, again reproduce it in precisely those forms which
alone require it, namely, the Cetacea? That such a harmless structure _need
not_ be removed any Darwinian must confess, since a structure exists in
both the crocodiles and gavials, which enables the former to breathe
themselves while drowning the prey which they hold in their mouths. On Mr.
Darwin's hypothesis it could only have been developed where useful,
therefore not in the gavials(!) which feed on fish, but which yet retain,
as we might expect, this, in them superfluous but harmless formation.
On the second alternative, how did the elongated larynx itself arise,
seeing that if its development lagged behind that of the maternal
structure, the young primeval kangaroo must be choked: while without the
injecting power in the mother, it must be starved? The struggle by the sole
action of which such a form was developed must indeed have been severe!
[Illustration: AN ECHINUS, OR SEA-URCHIN
(The spines removed from one-half.)]
The sea-urchins (Echinus) present us also with structures the origin of
which it seems impossible to explain by the action of "Natural {44}
Selection" only. These lowly animals belong to that group of the star-fish
class (Echinodermata), the species of which possess generally spheroidal
bodies, built up of multitudinous calcareous plates, and constitute the
order Echinoidea. They are also popularly known as sea-eggs. Utterly devoid
of limbs, the locomotion of these creatures is effected by means of rows of
small tubular suckers (which protrude through pores in the calcareous
plates) and by moveable spines scattered over the body.
[Illustration: PEDICELLARIÆ. (Immensely enlarged.)]
Besides these spines and suckers there are certain very peculiar
structures, termed "Pedicellariæ." Each of these consists of a long slender
stalk, ending in three short limbs--or rather jaws--the whole supported by
a delicate internal skeleton. The three limbs (or jaws), which start from a
common point at the end of the stalk, are in the constant habit of opening
and closing together again with a snapping action, while the stalk itself
sways about. The utility of these appendages is, even now, problematical.
It may be that they remove from the surface of the animal's body foreign
substances which would be prejudicial to it, and which it cannot otherwise
get rid of. But granting this, what would be the utility of the _first
rudimentary beginnings_ of such structures, and how could such incipient
buddings have ever preserved the life of a single Echinus? It is true that
on Darwinian principles the ancestral form from which the sea-urchin
developed was different, and must not be conceived merely as an Echinus
devoid of pedicellariæ; but this makes the difficulty none the less. It is
equally hard to imagine that the first rudiments of such structures could
have been useful to _any_ animal from which the Echinus might have been{45}
derived. Moreover, not even the _sudden_ development of the snapping action
could have been beneficial without the freely moveable stalk, nor could the
latter have been efficient without the snapping jaws, yet no minute merely
indefinite variations could simultaneously evolve these complex
co-ordinations of structure; to deny this seems to do no less than to
affirm a startling paradox.
Mr. Darwin explains the appearance of some structures, the utility of which
is not apparent, by the existence of certain "laws of correlation." By
these he means that certain parts or organs of the body are so related to
other organs or parts, that when the first are modified by the action of
"Natural Selection," or what not, the second are simultaneously affected,
and increase proportionally or possibly so decrease. Examples of such are
the hair and teeth in the naked Turkish dog, the general deafness of white
cats with blue eyes, the relation between the presence of more or less down
on young birds when first hatched, and the future colour of their
plumage,[36] with many others. But the idea that the modification of any
internal or external part of the body of an Echinus carries with it the
effect of producing elongated, flexible, triradiate, snapping processes,
is, to say the very least, fully as obscure and mysterious as what is here
contended for, viz. the efficient presence of an unknown internal natural
law or laws conditioning the evolution of new specific forms from preceding
ones, modified by the action of surrounding conditions, by "Natural
Selection" and by other controlling influences.
The same difficulty seems to present itself in other examples of
exceptional structure and action. In the same Echinus, as in many allied
forms, and also in some more or less remote ones, a very peculiar mode of
development exists. The adult is not formed from the egg directly, but {46}
the egg gives rise to a creature which swims freely about, feeds, and is
even somewhat complexly organized. Soon a small lump appears on one side of
its stomach; this enlarges, and, having established a communication with
the exterior, envelopes and appropriates the creature's stomach, with which
it swims away and develops into the complete adult form, while the
dispossessed individual perishes.
Again, certain flies present a mode of development equally bizarre, though
quite different. In these flies, the grub is, as usual, produced from the
ovum, but this grub, instead of growing up into the adult in the ordinary
way, undergoes a sort of liquefaction of a great part of its body, while
certain patches of formative tissue, which are attached to the ramifying
air tubes, or tracheæ (and which patches bear the name of "imaginal
disks"), give rise to the legs, wings, eyes, &c., respectively; and these
severally formed parts grow together, and build up the head and body by
their mutual approximation. Such a process is unknown outside the class of
insects, and inside that class it is only known in a few of the two-winged
flies. Now, how "Natural Selection," or any "laws of correlation," can
account for the gradual development of such an exceptional process of
development--so extremely divergent from that of other insects--seems
nothing less than inconceivable. Mr. Darwin himself[37] gives an account of
a very peculiar and abnormal mode of development of a certain beetle, the
sitaris, as described by M. Fabre. This insect, instead of at first
appearing in its grub stage, and then, after a time, putting on the adult
form, is at first active and furnished with six legs, two long antennæ, and
four eyes. Hatched in the nests of bees, it at first attaches itself to one
of the males, and then crawls, when the opportunity offers, upon a female
bee. When the female bee lays her eggs, the young sitaris springs upon them
and devours them. Then, losing its eyes, legs, and antennæ, and {47}
becoming rudimentary, it sinks into an ordinary grub-like form, and feeds
on honey, ultimately undergoing another transformation, re-acquiring its
legs, &c., and emerging a perfect beetle! That such a process should have
arisen by the accumulation of minute accidental variations in structure and
habit, appears to many minds, quite competent to form an opinion on the
subject, absolutely incredible.
It may be objected, perhaps, that these difficulties are _difficulties of
ignorance_--that we cannot explain them because we do not know _enough_ of
the animals. But it is here contended that this is not the case; it is not
that we merely fail to see how Natural Selection acted, but that there is a
positive incompatibility between the cause assigned and the results. It
will be stated shortly what wonderful instances of co-ordination and of
unexpected utility Mr. Darwin has discovered in orchids. The discoveries
are not disputed or undervalued, but the explanation of their _origin_ is
deemed thoroughly unsatisfactory--utterly insufficient to explain the
incipient, infinitesimal beginnings of structures which are of utility only
when they are considerably developed.
Let us consider the mammary gland, or breast. Is it conceivable that the
young of any animal was ever saved from destruction by accidentally sucking
a drop of scarcely nutritious fluid from an accidentally hypertrophied
cutaneous gland of its mother? And even if one was so, what chance was
there of the perpetuation of such a variation? On the hypothesis of Natural
Selection itself, we must assume that up to that time the race had been
well adapted to the surrounding conditions; the temporary and accidental
trial and change of conditions, which caused the so-sucking young one to be
the "fittest to survive" under the supposed circumstances, would soon cease
to act, and then the progeny of the mother, with the accidentally
hypertrophied, sebaceous glands, would have no tendency to survive the {48}
far outnumbering descendants of the normal ancestral form. If, on the other
hand, we assume the change of conditions not to have been temporary but
permanent, and also assume that this permanent change of conditions was
accidentally synchronous with the change of structure, we have a
coincidence of very remote probability indeed. But if, again, we accept the
presence of some harmonizing law simultaneously determining the two
changes, or connecting the second with the first by causation, then, of
course, we remove the accidental character of the coincidence.
Again, how explain the external position of the male sexual glands in
certain mammals? The utility of the modification, when accomplished, is
problematical enough, and no less so the incipient stages of the descent.
As was said in the first chapter, Mr. Darwin explains the brilliant plumage
of the peacock or the humming-bird by the action of sexual selection: the
more and more brilliant males being selected by the females (which are thus
attracted) to become the fathers of the next generation, to which
generation they tend to communicate their own bright nuptial vesture. But
there are peculiarities of colour and of form which it is exceedingly
difficult to account for by any such action. Thus, amongst apes, the female
is notoriously weaker, and is armed with much less powerful canine tusks
than the male. When we consider what is known of the emotional nature of
these animals, and the periodicity of its intensification, it is hardly
credible that a female would often risk life or limb through her admiration
of a trifling shade of colour, or an infinitesimally greater though
irresistibly fascinating degree of wartiness.[38]
{49}
[Illustration: RATTLESNAKE.]
Yet the males of some kinds of ape are adorned with quite exceptionally
brilliant local decoration, and the male orang is provided with remarkable,
projecting, warty lumps of skin upon the cheeks. As we have said, the
weaker female can hardly be supposed to have developed these by persevering
and long-continued selection, nor can they be thought to tend to the
preservation of the individual. On the contrary, the presence of this
enlarged appendage must occasion a slight increase in the need of
nutriment, and in so far must be a detriment, although its detrimental
effect would not be worth speaking of except in relation to "Darwinism,"
according to which, "selection" has acted through unimaginable ages, {50}
and has ever tended to suppress any useless development by the struggle for
life.[39]
[Illustration: COBRA.
(_Copied, by permission, from Sir Andrew Smith's "Reptiles of South
Africa."_)]
In poisonous serpents, also, we have structures which, at all events at
first sight, seem positively hurtful to those reptiles. Such are the rattle
of the rattlesnake, and the expanding neck of the cobra, the former seeming
to warn the ear of the intended victim, as the latter warns the eye. It is
true we cannot perhaps demonstrate that the victims are alarmed and warned,
but, on Darwinian principles, they certainly ought to be so. For the {51}
rashest and most incautious of the animals preyed on would always tend to
fall victims, and the existing individuals being the long-descended progeny
of the timid and cautious, ought to have an inherited tendency to distrust,
amongst other things, both "rattling" and "expanding" snakes. As to any
power of fascination exercised by means of these actions, the most
distinguished naturalists, certainly the most distinguished erpetologists,
entirely deny it, and it is opposed to the careful observations of those
known to us.[40]
The mode of formation of both the eye and the ear of the highest animals is
such that, if it is (as most Darwinians assert processes of development to
be) a record of the actual steps by which such structures were first
evolved in antecedent forms, it almost amounts to a demonstration that
those steps were never produced by "Natural Selection."
The eye is formed by a simultaneous and corresponding ingrowth of one part
and outgrowth of another. The skin in front of the future eye becomes
depressed, the depression increases and assumes the form of a sac, which
changes into the aqueous humour and lens. An outgrowth of brain substance,
on the other hand, forms the retina, while a third process is a lateral
ingrowth of connective tissue, which afterwards changes into the vitreous
humour of the eye.
The internal ear is formed by an involution of the integument, and not by
an outgrowth of the brain. But tissue, in connexion with it, becomes in
part changed, thus forming the auditory nerve, which places the tegumentary
sac in direct communication with the brain itself.
{52}
Now, these complex and simultaneous co-ordinations could never have been
produced by infinitesimal beginnings, since, until so far developed as to
effect the requisite junctions, they are useless. But the eye and ear when
fully developed present conditions which are hopelessly difficult to
reconcile with the mere action of "Natural Selection." The difficulties
with regard to the eye have been well put by Mr. Murphy, especially that of
the concordant result of visual development springing from different
starting-points and continued on by independent roads.
He says,[41] speaking of the beautiful structure of the perfect eye, "The
higher the organization, whether of an entire organism or of a single
organ, the greater is the number of the parts that co-operate, and the more
perfect is their co-operation; and consequently, the more necessity there
is for corresponding variations to take place in all the co-operating parts
at once, and the more useless will be any variation whatever unless it is
accompanied by corresponding variations in the co-operating parts; while it
is obvious that the greater the number of variations which are needed in
order to effect an improvement, the less will be the probability of their
all occurring at once. It is no reply to this to say, what is no doubt
abstractedly true, that whatever is possible becomes probable, if only time
enough be allowed. There are improbabilities so great that the common sense
of mankind treats them as impossibilities. It is not, for instance, in the
strictest sense of the word, impossible that a poem and a mathematical
proposition should be obtained by the process of shaking letters out of a
box; but it is improbable to a degree that cannot be distinguished from
impossibility; and the improbability of obtaining an improvement in an
organ by means of several spontaneous variations, all occurring together,
is an improbability of the same kind. If we suppose that any single
variation occurs on the average once in _m_ times, the probability of {53}
that variation occurring in any individual will be
1/_m_;
and suppose that _x_ variations must concur in order to make an
improvement, then the probability of the necessary variations all occurring
together will be
1/_m_^x.
Now suppose, what I think a moderate proposition, that the value of _m_ is
1,000, and the value of _x_ is 10, then
1/_m_^x = 1/1000^{10} = 1/10^{30}.
A number about ten thousand times as great as the number of waves of light
that have fallen on the earth since historical time began. And it is to be
further observed, that no improvement will give its possessor a _certainty_
of surviving and leaving offspring, but only an _extra chance_, the value
of which it is quite impossible to estimate." This difficulty is, as Mr.
Murphy points out, greatly intensified by the undoubted fact that the
wonderfully complex structure has been arrived at quite independently in
beasts on the one hand and in cuttle-fishes on the other; while creatures
of the insect and crab division present us with a third and quite
separately developed complexity.
As to the ear, it would take up too much space to describe its internal
structure;[42] it must suffice to say that in its interior there is an
immense series of minute rod-like bodies, termed _fibres of Corti_, having
the appearance of a key-board, and each fibre being connected with a
filament of the auditory nerve, these nerves being like strings to be
struck by the keys, _i.e._ by the fibres of Corti. Moreover, this apparatus
is supposed to be a key-board in function as well as in appearance, the{54}
vibration of each one fibre giving rise, it is believed, to the sensation
of one particular tone, and combinations of such vibrations producing
chords. It is by the action of this complex organ then, that all the
wonderful intricacy and beauty of Beethoven and Mozart come, most probably,
to be perceived and appreciated.
Now it can hardly be contended that the preservation of any race of men in
the struggle for life ever depended on such an extreme delicacy and
refinement of the internal ear,--a perfection only exercised in the
enjoyment and appreciation of the most perfect musical performances. How,
then, could either the minute incipient stages, or the final perfecting
touches of this admirable structure, have been brought about by vague,
aimless, and indefinite variations in all conceivable directions of an
organ, suitable to enable the rudest savage to minister to his necessities,
but no more?
Mr. Wallace[43] makes an analogous remark with regard to the organ of voice
in man--the human larynx. He says of singing: "The habits of savages give
no indication of how this faculty could have been developed by Natural
Selection, because it is never required or used by them. The singing of
savages is a more or less monotonous howling, and the females seldom sing
at all. Savages certainly never choose their wives for fine voices, but for
rude health, and strength, and physical beauty. Sexual selection could not
therefore have developed this wonderful power, which only comes into play
among civilized people."
Reverting once more to beauty of form and colour, there is one
manifestation of it for which no one can pretend that sexual selection can
possibly account. The instance referred to is that presented by bivalve
shell-fish.[44] Here we meet with charming tints and elegant forms and
markings of no direct use to their possessors[45] in the struggle for {55}
life, and of no indirect utility as regards sexual selection, for
fertilization takes place by the mere action of currents of water, and the
least beautiful individual has fully as good a chance of becoming a parent
as has the one which is the most favoured in beauty of form and colour.
Again, the peculiar outline and coloration of certain orchids--notably of
our own bee, fly, and spider orchids--seem hardly explicable by any action
of "Natural Selection." Mr. Darwin says very little on this singular
resemblance of flowers to insects, and what he does say seems hardly to be
what an advocate of "Natural Selection" would require. Surely, for minute
accidental indefinite variations to have built up such a striking
resemblance to insects, we ought to find that the preservation of the
plant, or the perpetuation of its race, depends almost constantly on
relations between bees, spiders, and flies respectively and the bee,
spider, and fly orchids.[46] This process must have continued for ages
constantly and perseveringly, and yet what is the fact? Mr. Darwin tells
us, in his work on the Fertilization of Orchids, that neither the spider
nor the fly orchids are much visited by insects, while, with regard to the
bee orchid, he says, "I have never seen an insect visit these flowers." And
he shows how this species is even wonderfully and specially modified to
effect self-fertilization.
In the work just referred to Mr. Darwin gives a series of the most
wonderful and minute contrivances by which the visits of insects are
utilized for the fertilization of orchids,--structures so wonderful {56}
that nothing could well be more so, except the attribution of their origin
to minute, fortuitous, and indefinite variation.
The instances are too numerous and too long to quote, but in his "Origin of
Species"[47] he describes two which must not be passed over. In one
(_Coryanthes_) the orchid has its lower lip enlarged into a bucket, above
which stand two water-secreting horns. These latter replenish the bucket
from which, when half-filled, the water overflows by a spout on one side.
Bees visiting the flower fall into the bucket and crawl out at the spout.
By the peculiar arrangement of the parts of the flower, the first bee which
does so carries away the pollen-mass glued to his back, and then when he
has his next involuntary bath in another flower, as he crawls out the
pollen-mass attached to him comes in contact with the stigma of that second
flower and fertilizes it. In the other example (_Catasetum_), when a bee
gnaws a certain part of the flower, he inevitably touches a long delicate
projection, which Mr. Darwin calls the antenna. "This antenna transmits a
vibration to a certain membrane, which is instantly ruptured; this sets
free a spring by which the pollen-mass is shot forth like an arrow in the
right direction, and adheres by its viscid extremity to the back of the
bee!"
Another difficulty, and one of some importance, is presented by those
communities of ants which have not only a population of sterile females, or
workers, but two distinct and very different castes of such. Mr. Darwin
believes that he has got over this difficulty by having found individuals
intermediate in form and structure[48] between the two working castes;
others may think that we have in this belief of Mr. Darwin, an example {57}
of the unconscious action of volition upon credence. A vast number of
difficulties similar to those which have been mentioned might easily be
cited--those given, however, may suffice.
There remains, however, to be noticed a very important consideration, which
was brought forward in the _North British Review_ for June 1867, p. 286,
namely, the necessity for the simultaneous modification of _many
individuals_. This consideration seems to have escaped Mr. Darwin, for at
p. 104 of his last (fifth) edition of "Natural Selection," he admits, with
great candour, that until reading this article he did not "appreciate how
rarely single variations, whether slight or strongly marked, could be
perpetuated."
The _North British Review_ (speaking of the supposition that a species is
changed by the survival of a few individuals in a century through a similar
and favourable variation) says: "It is very difficult to see how this can
be accomplished, even when the variation is eminently favourable indeed;
and still more difficult when the advantage gained is very slight, as must
generally be the case. The advantage, whatever it may be, is utterly
outbalanced by numerical inferiority. A million creatures are born; ten
thousand survive to produce offspring. One of the million has twice as good
a chance as any other of surviving; but the chances are fifty to one
against the gifted individuals being one of the hundred survivors. No doubt
the chances are twice as great against any one other individual, but this
does not prevent their being enormously in favour of _some_ average
individual. However slight the advantage may be, if it is shared by half
the individuals produced, it will probably be present in at least fifty-one
of the survivors, and in a larger proportion of their offspring; but the
chances are against the preservation of any one 'sport' (_i.e._ sudden,
marked variation) in a numerous tribe. The vague use of an imperfectly
understood doctrine of chance has led Darwinian supporters, first, to
confuse the two cases above distinguished; and, secondly, to imagine {58}
that a very slight balance in favour of some individual sport must lead to
its perpetuation. All that can be said is that in the above example the
favoured sport would be preserved once in fifty times. Let us consider what
will be its influence on the main stock when preserved. It will breed and
have a progeny of say 100; now this progeny will, on the whole, be
intermediate between the average individual and the sport. The odds in
favour of one of this generation of the new breed will be, say one and a
half to one, as compared with the average individual; the odds in their
favour will, therefore, be less than that of their parents; but owing to
their greater number, the chances are that about one and a half of them
would survive. Unless these breed together, a most improbable event, their
progeny would again approach the average individual; there would be 150 of
them, and their superiority would be, say in the ratio of one and a quarter
to one; the probability would now be that nearly two of them would survive,
and have 200 children, with an eighth superiority. Rather more than two of
these would survive; but the superiority would again dwindle, until after a
few generations it would no longer be observed, and would count for no more
in the struggle for life than any of the hundred trifling advantages which
occur in the ordinary organs. An illustration will bring this conception
home. Suppose a white man to have been wrecked on an island inhabited by
negroes, and to have established himself in friendly relations with a
powerful tribe, whose customs he has learnt. Suppose him to possess the
physical strength, energy, and ability of a dominant white race, and let
the food and climate of the island suit his constitution; grant him every
advantage which we can conceive a white to possess over the native; concede
that in the struggle for existence his chance of a long life will be much
superior to that of the native chiefs; yet from all these admissions, there
does not follow the conclusion that, after a limited or unlimited {59}
number of generations, the inhabitants of the island will be white. Our
shipwrecked hero would probably become king; he would kill a great many
blacks in the struggle for existence; he would have a great many wives and
children." ... "In the first generation there will be some dozens of
intelligent young mulattoes, much superior in average intelligence to the
negroes. We might expect the throne for some generations to be occupied by
a more or less yellow king; but can any one believe that the whole island
will gradually acquire a white, or even a yellow, population?"
"Darwin says that in the struggle for life a grain may turn the balance in
favour of a given structure, which will then be preserved. But one of the
weights in the scale of nature is due to the number of a given tribe. Let
there be 7000 A's and 7000 B's, representing two varieties of a given
animal, and let all the B's, in virtue of a slight difference of structure,
have the better chance of life by 1/7000 part. We must allow that there is
a slight probability that the descendants of B will supplant the
descendants of A; but let there be only 7001 A's against 7000 B's at first,
and the chances are once more equal, while if there be 7002 A's to start,
the odds would be laid on the A's. True, they stand a greater chance of
being killed; but then they can better afford to be killed. The grain will
only turn the scales when these are very nicely balanced, and an advantage
in numbers counts for weight, even as an advantage in structure. As the
numbers of the favoured variety diminish, so must its relative advantages
increase, if the chance of its existence is to surpass the chance of its
extinction, until hardly any conceivable advantage would enable the
descendants of a single pair to exterminate the descendants of many
thousands if they and their descendants are supposed to breed freely with
the inferior variety, and so gradually lose their ascendency."
Mr. Darwin himself says of the article quoted: "The justice of these
remarks cannot, I think, be disputed. If, for instance, a bird of some {60}
kind could procure its food more easily by having its beak curved, and if
one were born with its beak strongly curved, and which consequently
flourished, nevertheless there would be a very poor chance of this one
individual perpetuating its kind to the exclusion of the common form." This
admission seems almost to amount to a change of front in the face of the
enemy!
These remarks have been quoted at length because they so greatly intensify
the difficulties brought forward in this chapter. If the most favourable
variations have to contend with such difficulties, what must be thought as
to the chance of preservation of the slightly displaced eye in a sole or of
the incipient development of baleen in a whale?
SUMMARY AND CONCLUSION.
It has been here contended that a certain few facts, out of many which
might have been brought forward, are inconsistent with the origination of
species by "Natural Selection" only or mainly.
Mr. Darwin's theory requires minute, indefinite, fortuitous variations of
all parts in all directions, and he insists that the sole operation of
"Natural Selection" upon such is sufficient to account for the great
majority of organic forms, with their most complicated structures,
intricate mutual adaptations and delicate adjustments.
To this conception has been opposed the difficulties presented by such a
structure as the form of the giraffe, which ought not to have been the
solitary structure it is; also the minute beginnings and the last
refinements of protective mimicry equally difficult or rather impossible to
account for by "Natural Selection." Again the difficulty as to the heads of
flat-fishes has been insisted on, as also the origin, and at the same time
the constancy, of the limbs of the highest animals. Reference has also been
made to the whalebone of whales, and to the impossibility of {61}
understanding its origin through "Natural Selection" only; the same as
regards the infant kangaroo, with its singular deficiency of power
compensated for by maternal structures on the one hand, to which its own
breathing organs bear direct relation on the other. Again, the delicate and
complex pedicellariæ of Echinoderms, with a certain process of development
(through a secondary larva) found in that class, together with certain
other exceptional modes of development, have been brought forward. The
development of colour in certain apes, the hood of the cobra, and the
rattle of the rattlesnake have also been cited. Again, difficulties as to
the process of formation of the eye and ear, and as to the fully developed
condition of those complex organs, as well as of the voice, have been
considered. The beauty of certain shell-fish; the wonderful adaptations of
structure, and variety of form and resemblance, found in orchids; together
with the complex habits and social conditions of certain ants, have been
hastily passed in review. When all these complications are duly weighed and
considered, and when it is borne in mind how necessary it is for the
permanence of a new variety that many individuals in each case should be
simultaneously modified, the cumulative argument seems irresistible.
The Author of this book can say that though by no means disposed originally
to dissent from the theory of "Natural Selection," if only its difficulties
could be solved, he has found each successive year that deeper
consideration and more careful examination have more and more brought home
to him the inadequacy of Mr. Darwin's theory to account for the
preservation and intensification of incipient, specific, and generic
characters. That minute, fortuitous, and indefinite variations could have
brought about such special forms and modifications as have been enumerated
in this chapter, seems to contradict not imagination, but reason. [Page 62]
That either many individuals amongst a species of butterfly should be
simultaneously preserved through a similar accidental and minute variation
in one definite direction, when variations in many other directions would
also preserve; or that one or two so varying should succeed in supplanting
the progeny of thousands of other individuals, and that this should by no
other cause be carried so far as to produce the appearance (as we have
before stated) of spots of fungi, &c.--are alternatives of an improbability
so extreme as to be practically equal to impossibility.
In spite of all the resources of a fertile imagination, the Darwinian, pure
and simple, is reduced to the assertion of a paradox as great as any he
opposes. In the place of a mere assertion of our ignorance as to the way
these phenomena have been produced, he brings forward, as their
explanation, a cause which it is contended in this work is demonstrably
insufficient.
Of course in this matter, as elsewhere throughout nature, we have to do
with the operation of fixed and constant natural laws, and the knowledge of
these may before long be obtained by human patience or human genius; but
there is, it is believed, already enough evidence to show that these as yet
unknown natural laws or law will never be resolved into the action of
"Natural Selection," but will constitute or exemplify a mode and condition
of organic action of which the Darwinian theory takes no account
whatsoever. [Page 63]
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