On the Genesis of Species

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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: PLEURONECTIDAE, 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 (Pleuronectidae), 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 (Squalidae), 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 mammae, 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: PEDICELLARIAE. (Immensely enlarged.)]

Besides these spines and suckers there are certain very peculiar
structures, termed "Pedicellariae." 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 pedicellariae; 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 tracheae (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 antennae, 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 antennae, 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

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