[59] Elements of Geology, p. 280.

Lastly, the fact of the flora of the glacial epoch not having exhibited any modifications during the long residence of some of its specific types in Great Britain and elsewhere, is a fact of some importance to the general theory of evolution, since it shows a higher degree of stability on the part of these specific types than might perhaps have been expected, supposing the theory to be true. But I do not see that this constitutes a difficulty against the theory, when we have so many other cases of proved transmutation to set against it. For instance, not to go further afield than this very glacial flora itself, it will be remembered that in an earlier chapter I selected it as furnishing specially cogent proof of the transmutation of species. What, then, is the explanation of so extraordinary a difference between Mr. Carruthers' views and my own upon this point? I believe the explanation to be that he does not take a sufficiently wide survey of the facts.

To begin with, it seems to me that he exaggerates the vicissitudes to which the species of plants that he calls into evidence have been exposed while advancing before, and retreating after, the ice. Rather do I agree with Darwin that "they would not have been exposed during their long migrations to any great diversity of temperature; and as they all migrated in a body together, their mutual relations will not have been much disturbed; hence, in accordance with the principles indicated in this volume, these forms will not have been liable to much modification[60]." But, be this matter of opinion as it may, a much better test is afforded by those numerous cases all the world over, where arctic species have been left stranded on alpine areas by the retreat of glaciation; because here there is no room for differences of opinion as to a "change of environment" having taken place. Not to speak of climatic differences between arctic and alpine stations, consider merely the changes which must have taken place in the relations of the thus isolated species to each other, as well as to those of all the foreign plants, insects, &c., with which they have long been thrown into close association. If in such cases no variation or transmutation had taken place since the glacial epoch, then indeed there would have been a difficulty of some magnitude. But, by parity of reasoning, whatever degree of difficulty would have been thus presented is not merely discharged, but converted into at least an equal degree of corroboration, when it is found that under such circumstances, in whatever part of the world they have occurred, some considerable amount of variation and transmutation has always taken place,—and this in the animals as well as in the plants. For instance, again to quote Darwin, "If we compare the present Alpine plants and animals of the several great European mountain-ranges one with another, though many of the species remain identically the same, some exist as varieties, some as doubtful forms or sub-species, and some as distinct yet closely allied species representing each other on the several ranges[61]." Lastly, if instead of considering the case of alpine floras, we take the much larger case of the Old and New World as a whole, we meet with much larger proofs of the same general facts. For, "during the slowly decreasing warmth of the Pliocene period, as soon as the species in common, which inhabited the New and Old Worlds, migrated south of the Polar Circle, they will have been completely cut off from each other. This separation, as far as the more temperate productions are concerned, must have taken place long ages ago. As the plants and animals migrated southward, they will have become mingled in one great region with the native American productions, and would have had to compete with them; and, in the other great region, with those of the Old World. Consequently we have here everything favourable for much modification,—for far more modification than with the Alpine productions left isolated, within a much more recent period, on the several mountain ranges and on the arctic lands of Europe and N. America. Hence it has come, that when we compare the now living productions of the temperate regions of the New and Old Worlds, we find very few identical species; but we find in every class many forms, which some naturalists rank as geographical races, and others as distinct species; and a host of closely allied or representative forms which are ranked by all naturalists as specifically distinct[62]."

[60] Origin of Species, p. 332.

[61] Origin of Species, p. 332.

[62] Ibid. pp. 333-4.

In view then of all the above considerations—and especially those quoted from Darwin—it appears to me that far from raising any difficulty against the theory of evolution, the facts adduced by Mr. Carruthers make in favour of it. For when once these facts are taken in connection with the others above mentioned, they serve to complete the correspondence between degrees of modification with degrees of time on the one hand, and with degrees of evolution, of change of environment, &c., on the other. Or, in the words of Le Conte, when dealing with this very subject, "It is impossible to conceive a more beautiful illustration of the principles we have been trying to enforce[63]."

[63] Evolution and its Relation to Religious Thought, p. 194.



NOTE A TO PAGE 257.

The passages in Dr. Whewell's writings, to which allusion is here made, are somewhat too long to be quoted in the text. But as I think they deserved to be given, I will here reprint a letter which I wrote to Nature in March, 1888.

In his essay on the Reception of the Origin of Species, Prof. Huxley writes:—

"It is interesting to observe that the possibility of a fifth alternative, in addition to the four he has stated, has not dawned upon Dr. Whewell's mind" (Life and Lectures of Charles Darwin, vol. ii, p. 195).

And again, in the article Science, supplied to The Reign of Queen Victoria, he says:—

"Whewell had not the slightest suspicion of Darwin's main theorem, even as a logical possibility" (p 365).

Now, although it is true that no indication of such a logical possibility is to be met with in the History of the Inductive Sciences, there are several passages in the Bridgewater Treatise which show a glimmering idea of such a possibility. Of these the following are, perhaps, worth quoting. Speaking of the adaptation of the period of flowering to the length of a year, he says:—

"Now such an adjustment must surely be accepted as a proof of design, exercised in the formation of the world. Why should the solar year be so long and no longer? or, this being such a length, why should the vegetable cycle be exactly of the same length? Can this be chance?... And, if not by chance, how otherwise could such a coincidence occur than by an intentional adjustment of these two things to one another; by a selection of such an organization in plants as would fit them to the earth on which they were to grow; by an adaptation of construction to conditions; of the scale of construction to the scale of conditions? It cannot be accepted as an explanation of this fact in the economy of plants, that it is necessary to their existence; that no plants could possibly have subsisted, and come down to us, except those which were thus suited to their place on the earth. This is true; but it does not at all remove the necessity of recurring to design as the origin of the construction by which the existence and continuance of plants is made possible. A watch could not go unless there were the most exact adjustment in the forms and positions of its wheels; yet no one would accept it as an explanation of the origin of such forms and positions that the watch would not go if these were other than they were. If the objector were to suppose that plants were originally fitted to years of various lengths, and that such only have survived to the present time as had a cycle of a length equal to our present year, or one which could be accommodated to it, we should reply that the assumption is too gratuitous and extravagant to require much consideration."

Again, with regard to "the diurnal period," he adds:—

"Any supposition that the astronomical cycle has occasioned the physiological one, that the structure of plants has been brought to be what it is by the action of external causes, or that such plants as could not accommodate themselves to the existing day have perished, would be not only an arbitrary and baseless assumption, but, moreover, useless for the purposes of explanation which it professes, as we have noticed of a similar supposition with respect to the annual cycle."

Of course these passages in no way make against Mr. Huxley's allusions to Dr. Whewell's writings in proof that, until the publication of the Origin of Species, the "main theorem" of this work had not dawned on any other mind, save that of Mr. Wallace. But these passages show, even more emphatically than total silence with regard to the principle of survival could have done, the real distance which at that time separated the minds of thinking men from all that was wrapped up in this principle. For they show that Dr. Whewell, even after he had obtained a glimpse of the principle "as a logical possibility," only saw in it an "arbitrary and baseless assumption." Moreover, the passages show a remarkable juxtaposition of the very terms in which the theory of natural selection was afterwards formulated. Indeed, if we strike out the one word "intentional" (which conveys the preconceived idea of the writer, and thus prevented him from doing justice to any naturalistic view), all the following parts of the above quotations might be supposed to have been written by a Darwinian. "If not by chance, how otherwise could such a coincidence occur, than by an adjustment of these two things to one another; by a selection of such an organization in plants as would fit them to the earth on which they were to grow; by an adaptation of construction to conditions; of the scale of construction to the scale of conditions?" Yet he immediately goes on to say: "If the objector were to suppose that plants were originally fitted to years of various lengths, and that such only have survived to the present time ... as could be accommodated to it (i. e. the actual cycle), we should reply that the assumption is too gratuitous and extravagant to require much consideration." Was there ever a more curious exhibition of failure to perceive the importance of a "logical possibility"? And this at the very time when another mind was bestowing twenty years of labour on its "consideration."



NOTE B TO PAGE 295.

Since these remarks were delivered in my lectures as here printed, Mr. Mivart has alluded to the subject in the following and precisely opposite sense:—

Many of the more noteworthy instincts lead us from manifestations of purpose directed to the maintenance of the individual, to no less plain manifestations of a purpose directed to the preservation of the race. But a careful study of the interrelations and interdependencies which exist between the various orders of creatures inhabiting this planet shows us yet a more noteworthy teleology—the existence of whole orders of such creatures being directed to the service of other orders in various degrees of subordination and augmentation respectively. This study reveals to us, as a fact, the enchainment of all the various orders of creatures in a hierarchy of activities, in harmony with what we might expect to find in a world the outcome of a First Cause possessed of intelligence and will[64].

[64] On Truth, p. 493.

Having read this much, a Darwinian is naturally led to expect that Mr. Mivart is about to offer some examples of instincts or structures exemplifying what in the margin he calls the "Hierarchy of Ministrations." Yet the only facts he proceeds to adduce are the sufficiently obvious facts, that the inorganic world existed before the organic, plants before herbivorous animals, these before carnivorous, and so on: that is to say, everywhere the conditions to the occurrence of any given stage of evolution preceded such occurrence, as it is obvious that they must, if, as of course it is not denied, the possibility of such occurrence depended on the precedence of such conditions. Now, it is surely obvious that such a "hierarchy of ministrations" as this, far from telling against the theory of natural selection, is the very thing which tells most in its favour. The fact that animals, for instance, only appeared upon the earth after there were plants for them to feed upon, is clearly a necessity of the case, whether or not there was any design in the matter. Such "ministrations," therefore, as plant-organisms yield to animal-organisms is just the kind of ministration that the theory of natural selection requires. Thus far, then, both the theories—natural selection and super-natural design—have an equal right to appropriate the facts. But now, if in no one instance can it be shown that the ministration of plant-life to animal-life is of such a kind as to subserve the interests of animal-life without at the same time subserving those of the plant-life itself, then the fact makes wholly in favour of the naturalistic explanation of such ministration as appears. If any plants had presented any characters pointing prospectively to needs of animals without primarily ministering to their own, then, indeed, there would have been no room for the theory of natural selection. But as this can nowhere be alleged, the theory of natural selection finds all the facts to be exactly as it requires them to be: such ministration as plants yield to animals becomes so much evidence of natural selection having slowly formed the animals to appropriate the nutrition which the plants had previously gathered—and gathered under the previous influence of natural selection acting on themselves entirely for their own sakes. Therefore I say it is painfully manifest that "the enchainment of all the various orders of creatures in a hierarchy of activities," is not "in harmony with what we might expect to find in a world the outcome of a First Cause possessed of intelligence and [beneficent] will." So far as any argument from such "enchainment" reaches, it makes entirely against the view which Mr. Mivart is advocating. In point of fact, there is a total absence of any such "ministration" by one "order of creatures" to the needs of any other order, as the beneficent design theory would necessarily expect; while such ministration as actually does obtain is exactly and universally the kind which the naturalistic theory requires.

Again, quite independently, and still more recently, Mr. Mivart alluded in Nature (vol. xli, p. 41) to the difficulty which the apparently exceptional case of gall-formation presents to the theory of natural selection. Therefore I supplied (vol. xli, p. 80) the suggestion given in the text, viz. that although it appears impossible that the sometimes remarkably elaborate and adaptive structures of galls can be due to natural selection acting directly on the plants themselves—seeing that the adaptation has reference to the needs of their parasites—it is quite possible that the phenomena may be due to natural selection acting indirectly on the plants, by always preserving those individual insects (and larvae) the character of whose secretions is such as will best induce the particular shapes of galls that are required. Several other correspondents took part in the discussion, and most of them accepted the above explanation. Mr. T. D. A. Cockerell, however, advanced another and very ingenious hypothesis, showing that there is certainly one conceivable way in which natural selection might have produced all the phenomena of gall-formation by acting directly on the plants themselves[65]. Subsequently Mr. Cockerell published another paper upon the subject, stating his views at greater length. The following is the substance of his theory as there presented:—

[65] Nature, vol. xli, p. 344.

Doubtless there were internal plant-feeding larvae before there were galls: and, indeed, we have geological evidence that boring insects date very far back indeed. The primitive internal feeders, then, were miners in the roots, stems, twigs, or leaves, such as occur very commonly at the present day. These miners are excessively harmful to plant-life, and form a class of the most destructive insect-pests known to the farmer: they frequently cause the death of the whole or part of the plant attacked. Now, we may suppose that the secretions of certain of these insects caused a swelling to appear where the larvae lived, and on this excrescence the larvae fed. It is easy to see that the greater the excrescence, and the greater the tendency of the larvae to feed upon it, instead of destroying the vital tissues, the smaller is the amount of harm to the plant. Now the continued life and vitality of the plant is beneficial to the larvae, and the larger or more perfect the gall, the greater the amount of available food. Hence natural selection will have preserved and accumulated the gall-forming tendencies, as not only beneficial to the larvae, but as a means whereby the larvae can feed with least harm to the plant. So far from being developed for the exclusive benefit of the larvae, it is easy to see that, allowing a tendency to gall-formation, natural selection would have developed galls exclusively for the benefit of the plants, so that they might suffer a minimum of harm from the unavoidable attacks of insects.

But here it may be questioned—have we proof that internal feeders tend to form galls? In answer to this I would point out that gall-formation is a peculiar feature, and cannot be expected to arise in every group of internal feeders. But I think we can afford sufficient proof that wherever it has arisen it has been preserved; and further, that even the highly complex forms of galls are evolved from forms so simple that we hesitate to call them galls at all[66].

[66] Entomologist, March, 1890.

The paper then proceeds to give a number of individual cases. No doubt the principal objection to which Mr. Cockerell's hypothesis is open is one that was pointed out by Herr Wetterhan, viz. "the much greater facility afforded to the indirect action through insects, by the enormously more rapid succession of generations with the latter than with many of their vegetable hosts—oaks above all[67]." This difficulty, however, Mr. Cockerell believes maybe surmounted by the consideration that a growing plant need not be regarded as a single individual, but rather as an assemblage of such[68].

[67] Nature, vol. xli, p. 394.

[68] Ibid. vol. xli, pp. 559-560.



NOTE C TO PAGE 394.

The only remarks that Mr. Wallace has to offer on the pattern of colours, as distinguished from a mere brilliancy of colour, are added as an afterthought suggested to him by the late Mr. Alfred Tylor's book on Colouration of Animals and Plants (1886). But, in the first place, it appears to me that Mr. Wallace has formed an altogether extravagant estimate of the value of this work. For the object of the work is to show, "that diversified colouration follows the chief lines of structure, and changes at points, such as the joints, where function changes." Now, in publishing this generalization, Mr. Tylor—who was not a naturalist—took only a very limited view of the facts. When applied to the animal kingdom as a whole, the theory is worthless; and even within the limits of mammals, birds, and insects—which are the classes to which Mr. Tylor mainly applies it—there are vastly more facts to negative than to support it. This may be at once made apparent by the following brief quotation from Prof. Lloyd Morgan:—

It can hardly be maintained that the theory affords us any adequate explanation of the specific colour-tints of the humming-birds, or the pheasants, or the Papilionidae among butterflies. If, as Mr. Wallace argues, the immense tufts of golden plumage in the bird of paradise owe their origin to the fact that they are attached just above the point where the arteries and nerves for the supply of the pectoral muscles leave the interior of the body—and the physiological rationale is not altogether obvious,—are there no other birds in which similar arteries and nerves are found in a similar position? Why have these no similar tufts? And why, in the birds of paradise themselves, does it require four years ere these nervous and arterial influences take effect upon the plumage? Finally, one would inquire how the colour is determined and held constant in each species. The difficulty of the Tylor-Wallace view, even as a matter of origin, is especially great in those numerous cases in which the colour is determined by delicate lines, thin plates, or thin films of air or fluid. Mr. Poulton, who takes a similar line of argument in his Colours of Animals (p. 326), lays special stress on the production of white (pp. 201-202).

As regards the latter point, it may be noticed that not in any part of his writings, so far as I can find, does Mr. Wallace allude to the highly important fact of colours in animals being so largely due to these purely physical causes. Everywhere he argues as if colours were universally due to pigments; and in my opinion this unaccountable oversight is the gravest defect in Mr. Wallace's treatment both of the facts and the philosophy of colouration in the animal kingdom. For instance, as regards the particular case of sexual colouration, the oversight has prevented him from perceiving that his theory of "brilliancy" as due to "a surplus of vital energy," is not so much as logically possible in what must constitute at least one good half of the facts to which he applies it—unless he shows that there is some connection between vital energy and the development of striations, imprisonment of air-bubbles, &c. But any such connection—so essentially important for his theory—he does not even attempt to show. Lastly, and quite apart from these remarkable oversights, even if Mr. Tylor's hypothesis were as reasonable and well-sustained as it is fanciful and inadequate, still it could not apply to sexual colouration: it could apply only to colouration as affected by physiological functions common to both sexes. Yet it is in order to furnish a "preferable substitute" for Mr. Darwin's theory of sexual colouration, that Mr. Wallace adduces the hypothesis in question as one of "great weight"! In this matter, therefore, I entirely agree with Poulton and Lloyd Morgan.



INDEX

A.

Accident, Darwin's use of the word, 334-340; beauty due to, 408, 409.

Achromatin, 126-134.

Acquired characters, see Characters.

Acraea eurita, 328.

Adaptation, facts of, in relation to theory of natural selection, 401-403, 411.

Adaptive characters, see Characters.

AEsthetic sense in animals, 380-385; see Beautiful.

Agassiz, Prof. A., on fauna of the Mammoth cave, 70.

Alpine plants, 209, 210, 440-442.

Amauris niavius, 328.

Amblyornis inornata, 381-383.

Amphioxus, 137, 138, 145, 146.

Analogy, 38, 50-65, 176, 177, 347-350.

Anthropoid, see Apes.

Antlers, 98-100, 167-169.

Ants, co-operative instincts of, 268; leaf-cutting, 332; keeping aphides, 292.

Ape, eye of, 75; appendix vermiformis of, 84-86.

Apes, ears of, compared with those of man, 88; muscles of, 77, 82, 83; feet of, 77, 78; tail of, compared with that of man, 82-84; hair of, compared with that of man, 89-91; teeth of, compared with those of man, 92-94; flattening of tibiae of, 95, 96.

Aphides, 292.

Appendix vermiformis of man compared with that of orang, 84-86.

Apteryx, 68, 69.

Archaeopteryx, 171-173.

Arctic plants, 209, 210, 440-442.

Argyll, Duke of, on natural selection, 334-362.

Aristotle, his idea of scientific method, 1; on classification, 23, 24.

Arm, distribution of hair on, in man and apes, 89-92.

Arthropoda, embryology of, 155.

Artificial selection, analogy of, to natural selection, 295-314; pictorial representations of products of, 298-312.

Artiodactyls, 182-191.

Association, principle of, in aesthetics, 404-407.

Aster, 129-133.

Attraction-spheres, 128, 132, 133.

Australia, fauna of, 204, 205; thriving of exotic species in, 286; portrait of wild dog of, 304.

Azores, 224, 225.

B.

Bacon, Lord, on scientific method, 2.

Balanoglossus, 147, 148.

Baptanodon discus, posterior limb of, 179-181.

Barriers, in relation to geographical distribution, 216-224.

Bats, 56, 224, 226, 240.

Battle, law of, 385, 386.

Baya-bird, 381.

Bear, skeleton of, 174; feet of, 178.

Beautiful, the, sense of, in animals, 380-385; standards of, 380-404; Darwin's explanation of, in organic nature, 379-411; facts of, in inorganic nature in relation to Darwin's theory of, in organic, 404; often determined by natural selection, 406, 407; absent in many plants and animals, 408; in nature often accidental, 409-411; does not exist in organic nature as an end per se, 410, 411.

Bees, co-operative instincts of, 268.

Beetles, wingless, 68-70; on oceanic islands, 224, 226, 229, 232.

Bell, Dr., on natural theology, 412.

Bell-bird, 396-398.

Bembidium, 233.

Bermudas, 225-227.

Biology, ideas of method in, 1-9.

Birds, ovum of, 124; embryology of, 151-155; paleontology of, 163-165, 172, 173; brain of, 194-197; as carriers of seed, eggs, and small organisms, 217, 218; distribution of, 224-240; aesthetic sense of, 380-385; courtship of, 380-385.

Birgus latro, 62-65.

Blood, colour of arterial, 409.

Boar, see Pig.

Bombus lapidarius, 331.

Bower-birds, play-houses of, 381-383.

Boyd-Dawkins, on flattening of early human tibiae, 96.

Brain, palaeontology of, 194-197.

British Isles, see Islands.

Broca, 363.

Bronn, 363.

Budding, see Germination.

Burdon-Sanderson, Prof., on electric organ of skate, 366.

Butler, Bishop, on argument from ignorance, 41.

Butterflies, defensive colouring of, 321-329.

C.

Caesalpino, on classification, 24.

Calf, embryology of, 153.

Camel, foot of, 187-191.

Canadian stag, 196, 198, 199.

Canaries, portraits of, 303; first mentioned by Gesner, 312, 313.

Cape de Verde Archipelagoes, fauna of, 228.

Carcharias melanopterus, 149.

Carruthers, on evolution, 436-442.

Caterpillars, colours and forms of, 319, 322-326.

Cattle, portraits of, 311.

Causation, natural, 402, 413, 414.

Caves, faunas of dark, 70-72.

Cell, physiological, and properties of the, 104-134.

Cerura vinula, 325, 326.

Cervalces Americanus, 196, 198, 199.

Cervus dicrocerus, issiodorensis, matheronis, pardinensis, Sedgwickii, tetraceros, 168.

Chalmers, Dr., on natural theology, 412.

Chameleons, 317.

Characters, as adaptive, 273-276, 286-293, 349; as specific, 274-276, 286-295; as congenital and acquired, 274-276.

Chasmorhynchus niveus, and C. tricarunculatus, 396-398.

Chelydra serpentina, anterior limb of, 179-181.

Chick, embryology of, 153.

Chimpanzee, see Apes.

Chlorophyll, 408.

Chondracanthus cornutus, 122.

Cirripedes, 430.

Classification, 23-49; of organic nature by Genesis and Leviticus, 23; artificial and natural, 24-26; empirical rules of, 33-40; Darwin on, 35, 36, 39,40; form of, a nexus or tree, 29-32; of organic forms like that of languages, 32; single characters in relation to, 37; aggregates of characters in relation to, 35-37; adaptive and non-adaptive characters in relation to, 34, 35, 38, 39; chains of affinities in relation to, 39-40; biological differs from astronomical, 43.

Cockerell, on vegetable galls, 447, 448.

Colours, of plants and animals in relation to the theory of natural selection, 317-332; in relation to the theory of sexual selection, 391, 392, 394-396, 408-410, 448-450.

Colouring, see Recognition marks, Protective, Seasonal, Warning, and Mimicry.

Congenital characters, see Characters.

Conjugation, of Protozoa, 115-117.

Continuity, principle of, in nature, 15-21.

Contrivance, Darwin's use of the word, 281.

Co-operation, mutual, of species alleged, 445-448.

Co-operative instincts, due to natural selection, 267, 269.

Cope, Professor, his table of geological formations, 163, 164; his table of palaeontological development of feet, vertebral column, and brain, 197.

Correlation of growth, 357-362.

Cossonidae, 233.

Courtship, see Sexual Selection.

Crabs, 62-65, 139.

Cuttle-fish, 317.

Cuvier, on method in natural history, 3-4; on monkeys, 429.

Cyst, see Encystation.

D.

Darwin, Charles, his influence on ideas of method, 1-9; on classification, 35, 36, 39, 40; on vestigial characters in man, 77, 86, 87, 92; on imperfection of geological record, 165, and Appendix; on means of dispersal, 216, 218; on geographical distribution, 218, 219; on fauna of the Galapagos Archipelago, 227, 228; on natural selection, 252, 253, 255, 256, 286, 375, 376; his use of such words as 'accident,' 'fortuitous,' 'purpose,' 'contrivance,' &c., 281, 334-340; on sexual selection, 379-400.

Darwin, Erasmus, his theory of evolution, 253.

De Blainville, on the theory of descent, 258.

De Candolle, on classification, 34.

Deer, 98, 99, 167-169, 187, 191, 196, 198, 199.

Degeneration, 269, 270, 342.

Delamination, 139.

Diadema euryta, 330.

Diaster, 129-133.

Dingo, see Dog.

Dinornis, 60, 61.

Diptera mimicking Hymenoptera, 329.

Dog, dentition of, 39; Dingo, 304; domesticated varieties of, 305, 307; hairless, 307; skulls of, 307.

Duck, logger-headed, 68.

Dugong, eye of, 75.

E.

Eagle, eye of, 75.

Ear, of whales, 65; vestigial features of human, 76, 86-89; of man and apes compared, 88.

Eaton, Rev. A. E., on wingless insects, 70.

Echinodermata, 125-127, 138, 155.

Ectoderm, 137-142.

Egg, see Ovum.

Eimer, 363.

Elaps fulvius imitated by non-venomous snakes, 330.

Electric organs, 365-373.

Elephant, foot of, 185, 186; rate of propagation of, 261, 262.

Elk, 196-198, 199.

Embryo, human, see Man.

Embryogeny, see Ontogeny.

Embryology, 98-155.

Embryos, comparative series of, 152, 153.

Encyclopaedia Britannica, eighth ed., on instinct, 289-291.

Encystation of Protozoa, 115.

Endoderm, 137-142.

Equatorial plate, 129.

Equus, see Horse.

Erythrolamprus venustissimus, 330.

Evolution, organic, fact of, Section I; Method of, Section II; ideas upon, prior to Darwin, 253-258; divergent, 266, 267.

Ewart, Professor Cossar, on electric organ of skate, 364, 367.

Existence, see Struggle for.

Eye, of octopus, 57, 58, 347-350; absence of, in dark cave animals, 70-72; nictitating membrane of, 74, 75; development of, from cutaneous nerve-ending, 352-354.

F.

Feet, 51-59, 66, 77-80, 174-192, 197.

Fertilization of ova, 127, 128; of flowers by insects, 406.

Fish, embryology of, 143-155; palaeontology of, 163, 165, 169-171; brain of, 194-197; distribution of, 224-246; flying, 355.

Fission, reproduction by, 106, 107.

Flat fish, 317.

Float, see Swim-bladder.

Flowers, fertilization of, by insects, 406.

Fly, imitating a wasp, 329.

Flying-fish, and squirrels, 355.

Foraminifera, 346.

Forbes, H. O., on scapulo-coracoid bones of Dinornis, 60.

Fortuitous, Darwin's use of the word, 340.

Fossils, see Palaeontology.

Frogs, 317.

G.

Galapagos Islands, 227-231, 236, 237.

Galeus, eye of, 75.

Galls, vegetable, 293-295, 446-448.

Gastraea, 137-140.

Gastrophysema, 138.

Gastrulation, 137, 140.

Gegenbaur, 147, 181.

Gemmation, reproduction by, 106, 107, 110, 111.

Generalization, 5.

Generalized types, 33.

Genesis, classification of organic nature in, 23.

Genial tubercle, 96.

Geographical distribution, 204-248; see Glacial period, Barriers Transport of organisms, Oceanic islands, &c.

Geology, record of imperfect, 156-160, and Appendix; see Palaeontology.

Germs, prophetic, 272, 351-362.

Gesner, on classification, 24; on canaries, 313.

Gill-arches, 146, 147, 150, 151.

Gill-slits, 146, 147, 150-153.

Gills, of young salamanders, 102; origin of, in embryo, 144; of fish, 150, 152.

Giraffe, neck of, in relation to Lamarck's theory, 254.

Glacial periods, effects of, on distribution of plants and animals, 209, 210, and Appendix.

Goose, Frizzled, portrait of, 304.

Gorilla, see Apes.

Gray, Professor Asa, 337

Great-toe, in man and apes, 79-81.

Grouse, 317-319

Growth, correlation of, 357, 362.

Gymnotus, 365, 367.

H.

Haeckel, on analogy between species and languages, 32; on reproduction as discontinuous growth, 105, 106; his ideal primitive vertebrate, 143, 144.

Hair, vestigial characters of, in man, 89-92.

Hales, 3.

Haller, 3.

Hamilton, Sir William, 272.

Hands, 51-55, 66, 80-82, 174-192.

Hare, 318, 319.

Hartmann, on flattening of early human tibiae, 96.

Harvey, on Lord Bacon's writings, 2.

Heart, development of, 154.

Heilprin, on skulls of deer, 198, 199; on fossil shells, 201, 202.

Hen, ovum of, 122.

Heredity, in relation to classification, 28-31; in relation to embryology, 98-102; chromatin-fibres in relation to, 134; in relation to theories of organic evolution, 253-255, 260-264, 377.

Hermit-crabs, 62-65, 288, 289.

Heteromera, 233.

Hilgendorf, on shells of Planorbis, 201.

Hipparion, 191, 192.

Hippopotamus, foot of, 187.

Hog, see Pig.

Homology, 38, 50-65, 176, 177, 347-350, 357-359.

Homopterous insect, imitating leaf-cutting ants, 331, 332.

Hooker, Sir Joseph, on flora of St. Helena, 234.

Horns, 98-100, 167-169.

Horse, eye of, 75; limb-bones of, 176, 177, 186, 188-192; teeth of, 189-191; portraits of domesticated breeds of, 309.

Human, see Man.

Humerus, perforations of, in quadrumana and man, 94, 95.

Humming-birds, restricted to the New World, 211.

Hunter, 3; on ear of whale, 65.

Huxley, Prof., on mechanical selection, 283; on age of the earth, 435, 436; on Dr. Whewell, 243.

Hyatt, on shells of Planorbis, 201.

Hydra, 111, 122.

Hyrax, foot of, 185, 186.

I.

Ignorance, argument from, 41, 42, 49.

Illative Sense, 6.

Imitative colours, 317-323, 326-332.

Infant, feet of, 78, 79; grasping power of, 81.

Infertility, inter-specific, in relation to natural selection, 374-376.

Insects, wingless, 68-70; in primary formations, 163, Appendix; on oceanic islands, 224-238; in relation to galls, 293-295, 446-448; defensive colouring of, 321-332; fertilizing flowers, 406.

Instincts, always of primary use to species presenting them, 286-293.

Intercrossing, in relation to natural selection, 374-376.

Inutility of specific characters, in relation to natural selection, 374-376.

Islands, oceanic, 224-237; British, 238-241.

J.

Japan, hairless dog of, 101.

Jelly-fish, 119, 120.

K.

Kallima, 323.

Karyokinesis, 112-114, 128-134.

Kepler, 272.

Kerguelen Island, flightless insects of, 70.

Kropotkin, Prince, on co-operative instincts, 269.

L.

Lagopus mutus, 317, 318.

Lamarck, his method in natural history, 4; his theory of evolution, 253-256.

Lamprey, 148.

Languages, classification of, resembles that of organic forms, 32.

Lankester, E. Ray, on karyokinesis, 129, 130.

Leaf insect, 322.

Le Conte, on geological succession of animal classes, 164, 165; on types of tails, 169-173; on fossil shells of Planorbis, 201; his work on the relation of the theory of evolution to religious thought, 412.

Leptalis, 328.

Leuculmis echinus, 122.

Leviticus, classification of organic nature in, 23.

Life, origin of, 15.

Linnaeus, on method in natural history, 3; on classification, 26, 35-40.

Lion, skeleton of, 175; feet of, 178.

Lizard, heart and gill-arches of, 150.

Lloyd Morgan, 273, 449, 450.

Lungs, development of, 154, 354.

Lyell, Sir Charles, on classification, 32; on uniformitarianism, 258; on rational species, 344; on geological record, 420, 435, 439.

M.

Madeira, wingless beetles of, 68-70; peculiar beetles of, 226, 227.

Mammals, ovum of, 120-124; embryology of, 151-155; palaeontology of, 163, 165, 167, 180-199; limbs of, 174-178, 182-199; brain of, 194-199; of Australia and New Zealand, 204, 205; distribution of, on islands, 224-240.

Mammoth cave, fauna of, 70-72.

Man, nictitating membrane of, 75; vestigial muscles of, 76, 77, 82, 83; tail of, compared with that of apes, 82-84; hair of, compared with that of apes, 89-92; teeth of, compared with those of apes, 92-94; perforation of humerus of, 94, 95; flattening of ancient tibiae of, 95, 96; embryology of, 119, 153; hand of, 54; arm of, 90, 91; limb-bones of, 176, 177; palaeontology of, 163, 165; brain of, 194, 195; Mr. Syme on, 346, 347.

Marsh, on palaeontology of the horse, 188-190.

Matthew, Patrick, on natural selection, 257.

Mesoderm, 142.

Mesohippus, 189, 192.

Metaphyta, 104, 105.

Metazoa, 104.

Method, ideas of, in natural history, 1-9; of organic evolution, 252-261.

Meyer, Professor Ludwig, on helix of the human ear, 86.

Mimicry, 320-322.

Ministration, mutual, of species alleged, 445, 446.

Miohippus, 189.

Mivart, St. George, on eye of octopus, 57, 58, 348, 349; on incipient organs, 362; on mutual ministration of species, 445, 446.

Mollusca, shells of, 19, 199-203; eye of, 57, 58; embryology of, 155; palaeontology of, 163, 165.

Monkeys, why all, do not become men, 342-344.

Monotremata, 205.

Morgan, see Lloyd Morgan.

Morphology, 50-97.

Mule, portrait of, 309.

Multicellular organisms, 104.

Multiplication, see Reproduction.

N.

Naegeli, Prof., 337, 367.

Natural History, ideas of method in, 1-9.

Natural, interpretations as opposed to super-natural, 13-15; causation, 13-15.

Natural selection, 252-378, 401-410; Wells, Matthew, and Whewell on, 257, 258, 443-445; statement of theory of, 256-284; of evidences of, 285-332; of criticisms of, 333-378; relation of theory of, to religious thought, 401-410; preserves types, 264-267; cessation and reversal of, 270, 342; errors touching theory of, 270-284, 332-364; definition of, 275-376; antecedent standing of theory of, 277-284; Prof. Owen on, 333, 334; Duke of Argyll on, 334-362; Mr. Syme on, 340, 341, 345; need not always make for improvement, 341-347; homology and analogy in relation to, 347-350; often determines beauty, 406, 407; in relation to the formation of galls, 293-295. 446-448.

Nature, organic, 17; inorganic, 1, 17, 18.

Nauplius, 138.

Neumayr, 19.

New Zealand, fauna of, 68, 204, 205; thriving of exotic species in, 286.

Newman, on the Illative Sense, 6.

Newton, his idea of scientific method, 6.

Nictitating membrane, 74, 75.

Notochord, 146.

Novum Organon, the, on scientific method, 2.

Nucleus, 105, 112-134.

Nucleus-spindle, 129.

Nut-hatch, Syrian, ornamented nests of, 381.

O.

Objective methods, 6.

Oceanic islands, see Islands.

Octopus, eye of, 57, 58, 348-350.

[OE]dicnemus crepitans, 320.

Ontogeny, as recapitulation of phylogeny, 98-104.

Orang Outang, see Apes.

Oredon Culbertsoni, 167.

Origin of Species, the, influence exercised by, on ideas of method, 1-9

Orohippus, 189.

Otaria, eye of, 75.

Ovum, 113-142; human, 120-133; amoeboid movements of young, 121-123; segmentation of, 134, 135.

Owen, on ear of whale, 65; on natural selection, 333, 334.

Owl, eye of, 75.

P.

Paddle, see Whale, and Baptanodon discus.

Pagurus bernhardus, 64.

Pain, in relation to the theory of evolution, 417.

Palaeontology, 159-203; general testimony of, 156-165; testimony of, in particular cases, 165-203; consideration of objections to theory of evolution founded on grounds of, 156-165, and Appendix.

Palaeotherium, 190, 191.

Paley, on natural theology, 98, 412.

Paludina, successive forms of, 19.

Panama, Isthmus of, 219.

Panniculus carnosis, 77.

Papilio merope, 330.

Parasites, of animals, devoid of beauty, 408.

Parsimony, law of, 272.

Parthenogenesis, 119.

Partridges, 319.

Peacock, tail of, 378; courtship of, 383.

Peckham, Mr. and Mrs., on courtship of spiders, 388-390.

Perissodactyls, 182-192.

Petromyzon marinus, 148.

Phenacodus primaevus, 184, 185.

Phylogeny, see Ontogeny.

Physiological selection, 376.

Pig, embryology of, 153; feet of, 176, 187; portraits of wild and domesticated, 312.

Pigeons, portraits of, 298, 299; feather-footed, 359.

Pilot fish, 289.

Planorbis, transmutations of, 200, 201.

Pleasure and pain, in relation to the theory of evolution, 417.

Plica semilunaris, 75.

Pliohippus, 189.

Polar bear, skeleton of, 174; feet of, 178.

Polar bodies, 125, 126.

Polar star, 129.

Polyps, 114.

Porpoises, 24, 25, 50.

Poulton, E. B., on warning colours, 325, 326; on mimicry, 331, 332; sexual selection, 400, 401, 449, 450.

Poultry, portraits of, 300-302.

Pronucleus, 126-128.

Prophetic types, 272, 351-362.

Prophysema primordiale, 140.

Protective colouring, 317-323.

Protohippus, 189.

Protozoa, 104.

Ptarmigan, 317, 318.

Pterodactyl, wing of, 56.

Purpose, Darwin's use of the word, 281, 340.

Puss moth, larva of, 325, 326.

Python, 66, 67.

Q.

Quadrumana, muscles of, 76, 82, 83; perforations of humeri of, 94, 95; hair on phalanges of, 91.

R.

Rabbit, embryology of, 153; multiplication of, in Australia, 286; portraits of wild and domesticated breeds of, 308; protective colouring of, 319, 320.

Radiate form, beauty of, 408, 409.

Raia radiata, and batis, 367-371.

Rats, species of, restricted to Old and New Worlds, 212; British and Norwegian, 285, 286.

Rattle-snake, tail of, 289.

Recognition marks, 271-273.

Religion, in relation to Darwinism, 401-418.

Reproduction, different methods of, 106-117; essence of sexual, 110; foreshadowing of sexual in unicellular organisms, 115-117.

Reptiles, wing of flying, 56; rudimentary limbs of, 67; nictitating membrane of, 75; branchial arches of, 150; embryology of, 152; palaeontology of, 163, 165, 178-180; brain of, 194-197; distribution of, 224-240.

Rhinoceros, foot of, 186.

Robinson, Dr L., on grasping power of an infant's hands, 80-82.

Rudimentary organs, 65-97.

Ruminants, palaeontology of, 167, 168.

S.

Sacrum of man, compared with that of apes, 82-84.

Sagitta, 138.

Salamander, young of terrestrial, living in water, 102; embryology of, 152.

Sandwich Islands, 234-237.

Science, method of, 1-9.

Sclater, W. L., on a case of mimicry, 331, 332.

Scorpion in Silurian formation, 163.

Sea, lamprey, 148; destructive agency of the, 423, 424.

Seal, 51, 52, 75.

Seasonal changes of colour, 317-319.

Selection, value, 275; by physical processes, 282, 283, 335. See also Natural selection, Artificial selection, Sexual selection, Physiological selection.

Sentiency, in relation to the theory of evolution, 417.

Sex, difference of, restricted to Metazoa and Metaphyta, 105.

Sexual reproduction, see Reproduction.

Sexual selection, theory of, 277, 378-410; statement and evidences of, 379-391; criticisms of, 391-400; includes law of battle with that of charming, 385, 386; in relation to religious thought, 411-418; Tylor's theory substituted for, by Wallace, 449, 450.

Shark, eye of, 75; man-eating, 149; and pilot-fish, 289.

Sheep, limb-bones of, 176, 177; portraits of, 310.

Shells, of crabs, 62-64; palaeontology of mollusks, 199-203; land on oceanic islands, 224-240.

Silliman's Journal, on fauna of the Mammoth Cave, 70.

Skate, electric organ of, 364-373.

Skull, palaeontology of, 194-199; of bull-dog compared with that of deer-hound, 307.

Slavonia, Tertiary deposits of, 18, 19.

Species, not eternal, but either created or evolved, 13; named as such through absence of intermediate forms, 18-20; groups of, in classification, 20, and appearing suddenly in geological formations, 427-432, 437-440; origin of, coincide in space and time with pre-existing and allied species, 22; geographical distribution of, 204-248; extinct and living allied on same areas, 213; life of, preserved by natural selection, 264-270; not room for more than one rational, 344; characters of, 274-276, 286-295, 374-376; inter-sterility of allied, 374-376; mutual ministration of alleged, 445, 446.

Specific characters, see Characters.

Speculation, method of, 3-9.

Spencer, Herbert, on reproduction as discontinuous growth, 105, 106; on use-inheritance, 253-256; his failure to conceive the idea of natural selection, 257.

Spermatozoa, 123, 126-128.

Spiders, in primary formations, 163; courtship of, 388, 389.

Sponges, 122, 139, 140.

Spontaneous, Darwin's use of the term, 340.

Spores, 115.

Squirrels, flying, 355.

Sterility, see Infertility.

St. Helena, 231-234, 236-237.

St. Hilaire, 4.

Stick-insect, 322.

Stoat, 318.

Strombus accipilrinus, 201.

Strombus Leidy, 201.

Struggle for existence, 259-270.

Subjective, methods, 6.

Survival of the fittest, 335. See also Natural selection.

Swim-bladder of fish, 154, 354.

Symbiosis, 269.

Syme, David, on the theory of natural selection, 340, 341.

T.

Tail, types of, in fish and birds, 169-173.

Tasmanian wolf, dentition of, 39.

Teeth, of Tasmanian wolf, 39; molar, of man, compared with those of apes, 92-94; palaeontology of horses', 189-191.

Temperature, sense of, probable origin of that of sight, 353, 354.

Tennyson, 266.

Tibiae, flattening of, 95, 96.

Tissue-cells, see Cell.

Toes, 79, 80; see also Feet.

Tomes, C. S., on molar teeth of man and apes, 94.

Torpedo, 365, 367.

Tortoise, embryology of, 152, 154.

Toxopneustes variegatus, and T. lividus, 122.

Transport of organisms, means of, 207, 216-218.

Tribal fitness, as distinguished from individual, 267-269.

Trout, ovum of, 122.

Turtle, eye of, 75.

Tylor, Alfred, on colouration of animals, 448-450.

Type, preserved by natural selection, 264-269; improvement of, by natural selection, 269, 270; prophetic, 272, 351-362.

Types, as simple and generalized, 33.

U.

Unicellular organisms, 104.

Uraster, 138.

Utility, of specific characters, 274, 275; of incipient characters, 351-363; of electric organs, 365-373.

V.

Variation, in relation to natural selection, 263, 335-340, 377.

Verification, 6-9.

Vertebral column, embryology of 145, 146; palaeontology of, 192, 193.

Vertebrated animal, ideal primitive, 143, 144; embryology of, 143, 155.

Vespa vulgaris, 331.

Vestigial organs, 65-97.

Volucella inans, and V. bombylans, 329.

W.

Wagner, Moritz, on geographical distribution, 216.

Wallace, A. R., on origin of species as coincident in time and space with pre-existing and allied species, 22; on wingless insects, 70; on absence of hair from human back, and function of on arms of orang, 89; on geographical distribution, 207, 231, 232, 233, 243; on natural selection, 256; on recognition marks, 271-273; on alleged deductive consequences of the natural selection theory, 273-276; his theory of warning colours, 323, 324; on sexual selection, 391-400, 450; his principal defect in treating of animal colouration, 449, 450.

Warning colours, 323-326.

Wasp, imitated by a fly, 329.

Water-cress, multiplication of, in New Zealand, 286.

Weevils, on St. Helena, 232.

Weismann, his theory of heredity, 130, 134.

Wells, Dr., on natural selection, 257.

Wetterhan, Prof., on vegetable galls, 448.

Whales, 38, 50, 53, 54, 65, 180.

Whewell, on natural selection, 257, 258, 443-445.

Wings, 54-56, 60, 61, 68-70, 355.

Wolf, Tasmanian, dentition of, 34.

Wood, John, on vestigial muscles in man, 77.

Woodward, on fossil cirripedes, 431.

Woolner, on the human ear, 86.

Worms, embryology of, 155.

Wyman, Prof., on the great toe of human embryo, 79, 80.

Z.

Zona pellucida, 121.

Transcriber's Notes and Errata The following words were found in both hyphenated and unhyphenated forms in the text. The number of instances is given in parentheses after each word. deer-hound (2) deerhound (1) fresh-water (13) freshwater (1) inter-relations (1) interrelations (1) re-action (1) reaction (1) sea-weed (7) seaweed (1) super-natural (2) supernatural (24) wood-cut (3) woodcut (3) wood-cuts (4) woodcuts (1) There were 9 instances of 'larvae' and 3 instances of 'larvae'. The following typographical errors were corrected: Error Correction arboresent arborescent the The dicussion discussion In the index, the page entry for "Lyell, Sir Charles ... on geological record" was changed from '420' to '422'. Also, the page entry for "Natural selection ... definition of" was changed from '275-376' to '275-276'.

THE END