On the Genesis of Species

es.-Independent origins of similar sense organs.-The ear.-The eye.-Other coincidences.-Causes besides Natural Selection produce concordant variations in certain geographical regions.-Causes besides

and con

by indefinite, fortuitous,[49] minute variations in every part and in all directions-those variations only being preserved wh

PTERODACTYLE,

Mr. Andrew Murray's "Geograph

ying membrane of the bat's wing. Certain fishes and certain reptiles can also flit and take very prolonged jumps in the air. The flying-fish, however, takes these by means of a great elongation of the rays of the pectoral fins-parts which cannot be said to be of the same nature as the constituents of the wing of either the bat or the bird. The little lizard, which enjoys the formidable name of "flying-dragon," flits by means of a structure altogether peculiar-namely, by the liberation and great elongation of some of the ribs which support a fold of skin. In the extinct pterodactyles-which were truly flying reptiles-we meet with an approximation to the structure of the bat, but in the pterodactyle we have only one finger elongated in each hand: a striking example of how the very same function may be provided for by a modification similar in principle, yet surely manifesting the independence of its origin. When we go to lower animals, we find flight produced by organs, as the wings

F THE FLYI

ed ribs which suppor

oth. In wasps and bees the sting is formed of modified parts, accessory in reproduction. In the scorpion, we have the median terminal process of t

NTIP

is so improbable as to be practically impossible for two exactly similar structures to have ever been independently developed. It is so because the number of possible variations is in

to pure Darwinism, which makes use only of indirec

each animal and plant so acted on. Such theories have not to contend against the difficulty proposed, and it is here urged that even very complex extremely similar structures have again and again been developed quite independently one of the other, and this becau

unknown natural cause is to deny the purely Darwinian theory, which relies upon

of this very difficulty, and the calling his attention to the striking resemblance between certain teeth of

halangers, &c., of Australia), and the true opossums of America, called implacental Mammals. Now the placental mammals are subdivided into various orders, amongst which are the flesh-eaters (Carnivora, i.e. cats, dogs, otters, weasels, &c.), and the insect-eaters (Insectivora,

ures, in 1866, to promulgate the notion that a vast and widely-diffused marsupial fauna may have existed anteriorly to the development of the ordinary placental, non-pouche

OTRICHUS AN

e. These, indeed, are strikingly similar, but there are better examples still of this sort of coincidence. Thus it has often been remarked that the insectivoro

id?) in their jumping habits and long hind legs, but also in the structure of their molar teeth, and even f

The food of different kinds of apes is very different, yet how uniform is their dental structure! Again, who, looking at the teet

it has not met with any notable acceptance, and though he seems himself to have returned to the older notion,

l of the fittest. If, however, the Reader thinks that teeth are parts peculiarly qualified for rapid variation (in which view the Author cannot concur), he is requested to suspend his judgment till he has considered the question of the independent

learned Professor, refers to the structure of birds,

birds, however, present forms which, though closely resembling in the greater part of their structure, yet differ importantly the one from the other. One form is exemplified by the ostrich, rhe

class of birds so uniform and homogeneous should have had a double reptilian origin. If one set of birds sprang from one set of reptiles, and another set of birds from another set of reptiles, the two sets co

lly pointed out by Professor Huxley in his "Hunterian Course" for 1867, when attention was called to the existence in Dimorphodon macronyx of even that small process which in birds gives attachment to the upper end of the merrythought. Also Mr. Seeley[53] has shown that in pterodactyles, as in birds, the optic lobes of the brain were placed low down on each side-"lateral and depressed." Nevertheless, the view has been put forward and ably maintained by the same Professor,[54] as also by Professor Cope in the United States, that the line of descent from reptiles to birds has not been from ordinary reptiles, through pterodactyl

robably cerebral characters must have spontaneously and independently arisen. Here is a dilemma, either horn of which bears a

of the reptilian forms. But to this it may be replied that the ancient common stock could not have had at one and the same time a shoulder structure of both kinds. It must have been that of the struthious birds or that of the carinate birds, or something different from both. If it was that of the struthious birds, how did the pterodactyles and carinate birds independently arrive at the very same divergent structure? If it was that of the carinate

t up the shoulder structure of the pterodactyles and carinate birds, and have laterally depressed their optic lobes, at a time so far back as the deposition of the Oolite strata,[56] is a coincidence of the highest improbability; but that an innate power and evolutionary law, aided by the corrective action of "Natural Selection," should have furnished like needs with like aids, is not at all improbable. The difficulty does not tell against the theory of evolution, but on

RYX (of the O

xplain the difficulty as he does; but it would not

calcareous particles-otoliths), which are primitively or permanently lodged in two chambers, one on each side of the cartilaginous skull. The primitive cartilaginous cranium supports and protects the base of the brain, and the auditory nerves pass from that brain into the cartilaginous chambers to re

type of structure utterly remote from that on which the animals of the higher division provided with a spinal column are constructed. And indeed no transi

olith, and the auditory nerves pass from the cerebral ganglia into the cartilaginous chambers to reach the auditory sacs. Moreover, it has been suggested by Professor Owen that sinuosities between processes projecting from the inner wall of

LE-F

spect. B. Do

endence one of the other! It would be difficult to calculate the odds against the independent occurrence and conservation of two such complex series of merely accidental and minute haphazard variatio

ow many individuals of various kinds of four-gilled cephalopods have been found, it is fair to infer that at the least a certain small percentage of dibranchs would also have left traces of their presence had they existed. Thus it is probable that some four-gilled form was the progenitor of the dibranch cephalopods. Now the four-gilled kinds

fected in at least "three distinct lines of descent," alluding not only to the molluscous division of the animal kingdom, and the division provided with a spinal column, but also to a third primary division, namely, that which includes all insect

merely indefinite and minute accidental variations, is an improbability which amounts practically to impossibility. Moreover, we have here again the same imperfection of the four-gilled cephalopod, as compared with the two-gilled, and therefore (if the latter proceeded from the former) a similar indication of a certain comparative rapidity of development. Finally, and this is perhaps one of the most curious circumstances

ated that there is no such necessity as to the details of the process. For in the higher Annulosa, such as the dragon-fly, we meet with an eye of an unquestionably very high degree of efficiency, but formed on a type of structure only remot

ts have in many instances been arrived at; on the other hand, we have in the fish and the cephalopod not

the other, present us with residuary phenomena for which "Natural Selection" alone is quite incompetent to account. And that these same phenomena must therefore be considered

lves inexplicable by Natural Selection, but which are more readily to be explained by the action of the unknown law or la

OF AN ICH

he Ichthyosauria, and this not only in structures readily referable to similarity of habit, but in such matters as gre

odactyles; not only to a certain extent in the breast-bone and mode of supporting the flying membran

e shell, one valve of which is placed on each side) have their two shells united by one or two powerful muscles, which pass directly across from o

IDEA T

externally like a bivalve

in respect, the structure of true bivalves. Allusion is here made to certain small Crustacea-certain phyllopods and ostracods-which have the hard outer coat of their thorax so modified as to look wonderfully like a bivalve shell, although its nature and composition a

ITH BIRD'S-H

ations has been stated. But structures essentially similar (called avicularia, or "bird's-head processes") are developed from the surface o

r neck. The beak opens and shuts at intervals, like the jaws of the pedicellari? of the echinus, and there is altogether, in general principle, a remarkable similarity between the structures.

OCESSES VERY G

of the mother by means of vascular prominences. No trace of such a structure exists in any bird or in any reptile, and yet it crops out again in certain sharks. There indeed it

f any, nearer to an explanation of the phenomenon by means of "Natural Selection," for in the sharks in question the vascular prominences are deve

chinus minutissim

Mus delicatul

onvoluted windpipe of the sloth, reminding us of the condition of the windpipe in birds; and in another mammal, allied to the sloth, namely the great ant-eater (Myrmecoph

tadpole, and cuttle-fishes. As to entire external form, may be adduced the wonderful similarity between a true mouse (Mus delicatulus) and a small marsupial, pointed out by Mr. Andrew Murray in his work on the

emselves the species of Amboyna are the largest. 4. The species of Celebes equal or even surpass in size those of Amboyna. 5. The species and varieties of Celebes possess a striking character in the form of the anterior wings, different from that of the allied species and varieties of all the surrounding islands. 6. Tailed species in India or the Indian region become tailless as they spread eastward through the Archipelago. 7. In Amboyna and Ceram the females of several species are dull-coloured, while in the adjacent islands they are more brilliant." Again:[63] "In Amboyna and Ceram the female of the large and handsome Ornithoptera Helena has the large patch on the hind wings constantly of a pale dull ochre or buff colour; while in the scarcely distinguishable varieties from the adjacent islands, of Bouru and New Guinea, it is of a golden yellow, hardly inferior in brilliancy to its colour in

less gaily attired than the corresponding females of the surrounding islands, are questions which we cannot at present attempt to answer. That they depend, however, on some general principle is certain, because analogous facts have been observed in other parts of the world. Mr. Bates informs me that, in three distinct groups, Papilios, which, on the Upper Amazon, and in most other parts of South America, have spotless upper wings, obtain pale or white spots at Pará and on the Lower Amazon, and also that the ?neas group of Papilios never have tails in the equatorial reg

fully studied in relation to those of the surrounding countries; and they seem to indicate that climate and other physical causes have, in

ES OF CELEBES COMPARED WITH TH

ore and Java.-2. Outer outline, P. miletus, of Celebes. Inner outline, P. sarpe

t some time of special persecutors of the modified forms, supporting the opinion by the remark that small, obscure, very rapidly flying and mimicked kinds have not had the wing modified. Such an enemy occasioning increased powers of flight, or rapidity in turning, he adds, "one would naturally suppose to be an insectivorous bird; but it is a remarkable fact that most of the genera of fly-catchers of Borneo and Java on the one side, and of the Moluccas on the other, are almost enti

y birds of which it can only be said that it is "highly probable" that they chase butterflies "when other food is scarce." The quick eye of Mr. Wallace failed to detect them in the act, as also to note any unusual abundance of other insectivorous forms, which therefore, considering Mr. Wallace's zeal and powers of observation, we may conclude do not exist. Moreover

lieving that birds of the same species are more brightly coloured under a clear atmosphere, than when living on islands or near the coast. Mr. Darwin also informs us that Wollaston is convinced that residence near the sea affects the colour of insects; and finally, that Moquin-Tandon gives a list of plants which, when growing near the sea-shore, have their leaves in some degree fleshy, though not so elsewhere. In his work on "Animals and Plants under Domestication,"[68] Mr. Darwin refers to M. Costa as having (in Bull. de la Soc. Imp. d'Accli

admitted opinion that a new type has been developed in the United States, and this in about a couple of centuries only, and in a va

SHIELDED G

on to members of such groups, which nature and tendency seem to induce them to vary in certain definite lines or directions which are different in different groups. Thus with regard to the group of insects, of which the walking leaf is a member, Mr. Wa

FTED BIRD O

gregarious honey-suckers. Now, many other birds would be benefited by similar mimicry, which is none the less confined, in this part of the world, to the oriole genus. It is true that the absence of mimicry in other forms may be explained by their possess

ILED BIRD O

ich agree in developing plumage unequalled in beauty, but a beauty which, as to details, is of different kinds, and produced in different ways in different

d in a common peculiarity, but in one singularly different in detai

a number of species which offer strange and bizarre approximations to different animal form

ED F

CENT BIRD O

fficient to point towards the conclusion which other facts will, it is thought, establish, viz. that there are causes operating (in the evocation of these harm

, between the several joints of the backbone), which are certainly not so explicable. This, however, leads to a rather large subject, which will be spoken of in the eighth chapter of the present work. Here it will be enough to affirm (leaving th

not suppose the carbonates and phosphates found in various parts of the globe-we do not suppose that the families of alkaloids and salts have any nearer kinship than that which consists in the similar

lection from parents specifically distinct, but he will not deny that identical forms may issue from parents genetically distin

scent; that is, by considering such similar forms as the descendants of atoms which inhabited one special part of the primitive n

have produced others by generative multiplication, which mineral atoms never did. In the second, existing animals and plants spring from the living tissues of preceding animals and plants, while existing minerals spri

er the requisite external conditions) certain unions with other atoms, so we may attribute to certain mineral species-as crystals-an innate power and tendency to exhibit (the proper conditions being supplied) a definite and symmetrical external form. The distinction between animals and vegetables on

organisms-it will be necessary to return somewhat to the subject of the independent origin of closely simi

ortant influence is exercised by conditions connected with geographical distribution, but that a deeper-seated influence is at work, which is hinted at by those special tendencies in definite directions, which are the properties of certain groups. Finally, that these facts, wh