Chapter XV: Darwinism Applied to Man (2)

The law of Natural Selection or the survival of the fittest is, as its name implies, a rigid law, which acts by the life or death of the individuals submitted to its action. From its very nature it can act only on useful or hurtful characteristics, eliminating the latter and keeping up the former to a fairly general level of efficiency. Hence it necessarily follows that the characters developed by its means will be present in all the individuals of a species, and, though varying, will not vary very widely from a common standard. The amount of variation we found, in our third chapter, to be about one-fifth or one-sixth of the mean value--that is, if the mean value were taken at 100, the variations would reach from 80 to 120, or somewhat more, if very large numbers were compared. In accordance with this law we find, that all those characters in man which were certainly essential to him during his early stages of development, exist in all savages with some approach to equality. In the speed of running, in bodily strength, in skill with weapons, in acuteness of vision, or in power of following a trail, all are fairly proficient, and the differences of endowment do not probably exceed the limits of variation in animals above referred to. So, in animal instinct or intelligence, we find the same general level of development. Every wren makes a fairly good nest like its fellows; every fox has an average amount of the sagacity of its race; while all the higher birds and mammals have the necessary affections and instincts needful for the protection and bringing-up of their offspring.

But in those specially developed faculties of civilised man which we have been considering, the case is very different. They exist only in a small proportion of individuals, while the difference of capacity between these favoured individuals and the average of mankind is enormous. Taking first the mathematical faculty, probably fewer than one in a hundred really possess it, the great bulk of the population having no natural ability for the study, or feeling the slightest interest in it.[234] And if we attempt to measure the amount of variation in the faculty itself between a first-class mathematician and the ordinary run of people who find any kind of calculation confusing and altogether devoid of interest, it is probable that the former could not be estimated at less than a hundred times the latter, and perhaps a thousand times would more nearly measure the difference between them.

The artistic faculty appears to agree pretty closely with the mathematical in its frequency. The boys and girls who, going beyond the mere conventional designs of children, draw what they _see_, not what they _know_ to be the shape of things; who naturally sketch in perspective, because it is thus they see objects; who see, and represent in their sketches, the light and shade as well as the mere outlines of objects; and who can draw recognisable sketches of every one they know, are certainly very few compared with those who are totally incapable of anything of the kind. From some inquiries I have made in schools, and from my own observation, I believe that those who are endowed with this natural artistic talent do not exceed, even if they come up to, one per cent of the whole population.

The variations in the amount of artistic faculty are certainly very great, even if we do not take the extremes. The gradations of power between the ordinary man or woman "who does not draw," and whose attempts at representing any object, animate or inanimate, would be laughable, and the average good artist who, with a few bold strokes, can produce a recognisable and even effective sketch of a landscape, a street, or an animal, are very numerous; and we can hardly measure the difference between them at less than fifty or a hundred fold.

The musical faculty is undoubtedly, in its lower forms, less uncommon than either of the preceding, but it still differs essentially from the necessary or useful faculties in that it is almost entirely wanting in one-half even of civilised men. For every person who draws, as it were instinctively, there are probably five or ten who sing or play without having been taught and from mere innate love and perception of melody and harmony.[235] On the other hand, there are probably about as many who seem absolutely deficient in musical perception, who take little pleasure in it, who cannot perceive discords or remember tunes, and who could not learn to sing or play with any amount of study. The gradations, too, are here quite as great as in mathematics or pictorial art, and the special faculty of the great musical composer must be reckoned many hundreds or perhaps thousands of times greater than that of the ordinary "unmusical" person above referred to.

It appears then, that, both on account of the limited number of persons gifted with the mathematical, the artistic, or the musical faculty, as well as from the enormous variations in its development, these mental powers differ widely from those which are essential to man, and are, for the most part, common to him and the lower animals; and that they could not, therefore, possibly have been developed in him by means of the law of natural selection.

* * * * *

We have thus shown, by two distinct lines of argument, that faculties are developed in civilised man which, both in their mode of origin, their function, and their variations, are altogether distinct from those other characters and faculties which are essential to him, and which have been brought to their actual state of efficiency by the necessities of his existence. And besides the three which have been specially referred to, there are others which evidently belong to the same class. Such is the metaphysical faculty, which enables us to form abstract conceptions of a kind the most remote from all practical applications, to discuss the ultimate causes of things, the nature and qualities of matter, motion, and force, of space and time, of cause and effect, of will and conscience. Speculations on these abstract and difficult questions are impossible to savages, who seem to have no mental faculty enabling them to grasp the essential ideas or conceptions; yet whenever any race attains to civilisation, and comprises a body of people who, whether as priests or philosophers, are relieved from the necessity of labour or of taking an active part in war or government, the metaphysical faculty appears to spring suddenly into existence, although, like the other faculties we have referred to, it is always confined to a very limited proportion of the population.

In the same class we may place the peculiar faculty of wit and humour, an altogether natural gift whose development appears to be parallel with that of the other exceptional faculties. Like them, it is almost unknown among savages, but appears more or less frequently as civilisation advances and the interests of life become more numerous and more complex. Like them, too, it is altogether removed from utility in the struggle for life, and appears sporadically in a very small percentage of the population; the majority being, as is well known, totally unable to say a witty thing or make a pun even to save their lives.[236]

_The Interpretation of the Facts._

The facts now set forth prove the existence of a number of mental faculties which either do not exist at all or exist in a very rudimentary condition in savages, but appear almost suddenly and in perfect development in the higher civilised races. These same faculties are further distinguished by their sporadic character, being well developed only in a very small proportion of the community; and by the enormous amount of variation in their development, the higher manifestations of them being many times--perhaps a hundred or a thousand times--stronger than the lower. Each of these characteristics is totally inconsistent with any action of the law of natural selection in the production of the faculties referred to; and the facts, taken in their entirety, compel us to recognise some origin for them wholly distinct from that which has served to account for the animal characteristics--whether bodily or mental--of man.

The special faculties we have been discussing clearly point to the existence in man of something which he has not derived from his animal progenitors--something which we may best refer to as being of a spiritual essence or nature, capable of progressive development under favourable conditions. On the hypothesis of this spiritual nature, superadded to the animal nature of man, we are able to understand much that is otherwise mysterious or unintelligible in regard to him, especially the enormous influence of ideas, principles, and beliefs over his whole life and actions. Thus alone we can understand the constancy of the martyr, the unselfishness of the philanthropist, the devotion of the patriot, the enthusiasm of the artist, and the resolute and persevering search of the scientific worker after nature's secrets. Thus we may perceive that the love of truth, the delight in beauty, the passion for justice, and the thrill of exultation with which we hear of any act of courageous self-sacrifice, are the workings within us of a higher nature which has not been developed by means of the struggle for material existence.

It will, no doubt, be urged that the admitted continuity of man's progress from the brute does not admit of the introduction of new causes, and that we have no evidence of the sudden change of nature which such introduction would bring about. The fallacy as to new causes involving any breach of continuity, or any sudden or abrupt change, in the effects, has already been shown; but we will further point out that there are at least three stages in the development of the organic world when some new cause or power must necessarily have come into action.

The first stage is the change from inorganic to organic, when the earliest vegetable cell, or the living protoplasm out of which it arose, first appeared. This is often imputed to a mere increase of complexity of chemical compounds; but increase of complexity, with consequent instability, even if we admit that it may have produced protoplasm as a chemical compound, could certainly not have produced _living_ protoplasm--protoplasm which has the power of growth and of reproduction, and of that continuous process of development which has resulted in the marvellous variety and complex organisation of the whole vegetable kingdom. There is in all this something quite beyond and apart from chemical changes, however complex; and it has been well said that the first vegetable cell was a new thing in the world, possessing altogether new powers--that of extracting and fixing carbon from the carbon-dioxide of the atmosphere, that of indefinite reproduction, and, still more marvellous, the power of variation and of reproducing those variations till endless complications of structure and varieties of form have been the result. Here, then, we have indications of a new power at work, which we may term _vitality_, since it gives to certain forms of matter all those characters and properties which constitute Life.

The next stage is still more marvellous, still more completely beyond all possibility of explanation by matter, its laws and forces. It is the introduction of sensation or consciousness, constituting the fundamental distinction between the animal and vegetable kingdoms. Here all idea of mere complication of structure producing the result is out of the question. We feel it to be altogether preposterous to assume that at a certain stage of complexity of atomic constitution, and as a necessary result of that complexity alone, an _ego_ should start into existence, a thing that _feels_, that is _conscious_ of its own existence. Here we have the certainty that something new has arisen, a being whose nascent consciousness has gone on increasing in power and definiteness till it has culminated in the higher animals. No verbal explanation or attempt at explanation--such as the statement that life is the result of the molecular forces of the protoplasm, or that the whole existing organic universe from the amaeba up to man was latent in the fire-mist from which the solar system was developed--can afford any mental satisfaction, or help us in any way to a solution of the mystery.

The third stage is, as we have seen, the existence in man of a number of his most characteristic and noblest faculties, those which raise him furthest above the brutes and open up possibilities of almost indefinite advancement. These faculties could not possibly have been developed by means of the same laws which have determined the progressive development of the organic world in general, and also of man's physical organism.[237]

These three distinct stages of progress from the inorganic world of matter and motion up to man, point clearly to an unseen universe--to a world of spirit, to which the world of matter is altogether subordinate. To this spiritual world we may refer the marvellously complex forces which we know as gravitation, cohesion, chemical force, radiant force, and electricity, without which the material universe could not exist for a moment in its present form, and perhaps not at all, since without these forces, and perhaps others which may be termed atomic, it is doubtful whether matter itself could have any existence. And still more surely can we refer to it those progressive manifestations of Life in the vegetable, the animal, and man--which we may classify as unconscious, conscious, and intellectual life,--and which probably depend upon different degrees of spiritual influx. I have already shown that this involves no necessary infraction of the law of continuity in physical or mental evolution; whence it follows that any difficulty we may find in discriminating the inorganic from the organic, the lower vegetable from the lower animal organisms, or the higher animals from the lowest types of man, has no bearing at all upon the question. This is to be decided by showing that a change in essential nature (due, probably, to causes of a higher order than those of the material universe) took place at the several stages of progress which I have indicated; a change which may be none the less real because absolutely imperceptible at its point of origin, as is the change that takes place in the curve in which a body is moving when the application of some new force causes the curve to be slightly altered.

_Concluding Remarks._

Those who admit my interpretation of the evidence now adduced--strictly scientific evidence in its appeal to facts which are clearly what ought _not_ to be on the materialistic theory--will be able to accept the spiritual nature of man, as not in any way inconsistent with the theory of evolution, but as dependent on those fundamental laws and causes which furnish the very materials for evolution to work with. They will also be relieved from the crushing mental burthen imposed upon those who--maintaining that we, in common with the rest of nature, are but products of the blind eternal forces of the universe, and believing also that the time must come when the sun will lose his heat and all life on the earth necessarily cease--have to contemplate a not very distant future in which all this glorious earth--which for untold millions of years has been slowly developing forms of life and beauty to culminate at last in man--shall be as if it had never existed; who are compelled to suppose that all the slow growths of our race struggling towards a higher life, all the agony of martyrs, all the groans of victims, all the evil and misery and undeserved suffering of the ages, all the struggles for freedom, all the efforts towards justice, all the aspirations for virtue and the wellbeing of humanity, shall absolutely vanish, and, "like the baseless fabric of a vision, leave not a wrack behind."

As contrasted with this hopeless and soul-deadening belief, we, who accept the existence of a spiritual world, can look upon the universe as a grand consistent whole adapted in all its parts to the development of spiritual beings capable of indefinite life and perfectibility. To us, the whole purpose, the only _raison d'être_ of the world--with all its complexities of physical structure, with its grand geological progress, the slow evolution of the vegetable and animal kingdoms, and the ultimate appearance of man--was the development of the human spirit in association with the human body. From the fact that the spirit of man--the man himself--_is_ so developed, we may well believe that this is the only, or at least the best, way for its development; and we may even see in what is usually termed "evil" on the earth, one of the most efficient means of its growth. For we know that the noblest faculties of man are strengthened and perfected by struggle and effort; it is by unceasing warfare against physical evils and in the midst of difficulty and danger that energy, courage, self-reliance, and industry have become the common qualities of the northern races; it is by the battle with moral evil in all its hydra-headed forms, that the still nobler qualities of justice and mercy and humanity and self-sacrifice have been steadily increasing in the world. Beings thus trained and strengthened by their surroundings, and possessing latent faculties capable of such noble development, are surely destined for a higher and more permanent existence; and we may confidently believe with our greatest living poet--

That life is not as idle ore,

But iron dug from central gloom,
And heated hot with burning fears,
And dipt in baths of hissing tears,
And batter'd with the shocks of doom

To shape and use.

We thus find that the Darwinian theory, even when carried out to its extreme logical conclusion, not only does not oppose, but lends a decided support to, a belief in the spiritual nature of man. It shows us how man's body may have been developed from that of a lower animal form under the law of natural selection; but it also teaches us that we possess intellectual and moral faculties which could not have been so developed, but must have had another origin; and for this origin we can only find an adequate cause in the unseen universe of Spirit.

FOOTNOTES:

[Footnote 218: _Descent of Man_, pp. 41-43; also pp. 13-15.]

[Footnote 219: _Man's Place in Nature_, p. 64.]

[Footnote 220: _Man's Place in Nature_, p. 67. See Figs. of Embryos of Man and Dog in Darwin's _Descent of Man_, p. 10.]

[Footnote 221: _The Descent of Man_, pp. 7, 8.]

[Footnote 222: _Man and Apes._ By St. George Mivart, F.R.S., 1873. It is an interesting fact (for which I am indebted to Mr. E.B. Poulton) that the human embryo possesses the extra rib and wrist-bone referred to above in (2) and (4) as occurring in some of the apes.]

[Footnote 223: _Man and Apes_, pp. 138, 144.]

[Footnote 224: For a sketch of the evidence of Man's Antiquity in America, see _The Nineteenth Century_ for November 1887.]

[Footnote 225: This subject was first discussed in an article in the _Anthropological Review_, May 1864, and republished in my _Contributions to Natural Selection_, chap, ix, in 1870.]

[Footnote 226: _Man's Place in Nature_, p. 102.]

[Footnote 227: For a full discussion of this question, see the author's _Geographical Distribution of Animals_, vol. i. p. 285.]

[Footnote 228: For a full discussion of all these points, see _Descent of Man_, chap. iii.]

[Footnote 229: _Descent of Man_, chap. iv.]

[Footnote 230: Lubbock's _Origin of Civilisation_, fourth edition, pp. 434-440; Tylor's _Primitive Culture_, chap. vii.]

[Footnote 231: It has been recently stated that some of these facts are erroneous, and that some Australians can keep accurate reckoning up to 100, or more, when required. But this does not alter the general fact that many low races, including the Australians, have no words for high numbers and never require to use them. If they are now, with a little practice, able to count much higher, this indicates the possession of a faculty which could not have been developed under the law of utility only, since the absence of words for such high numbers shows that they were neither used nor required.]

[Footnote 232: Article Arithmetic in _Eng. Cyc. of Arts and Sciences_.]

[Footnote 233: See "History of Music," in _Eng. Cyc._, Science and Arts Division.]

[Footnote 234: This is the estimate furnished me by two mathematical masters in one of our great public schools of the proportion of boys who have any special taste or capacity for mathematical studies. Many more, of course, can be drilled into a fair knowledge of elementary mathematics, but only this small proportion possess the natural faculty which renders it possible for them ever to rank high as mathematicians, to take any pleasure in it, or to do any original mathematical work.]

[Footnote 235: I am informed, however, by a music master in a large school that only about one per cent have real or decided musical talent, corresponding curiously with the estimate of the mathematicians.]

[Footnote 236: In the latter part of his essay on Heredity (pp. 91-93 of the volume of _Essays_), Dr. Weismann refers to this question of the origin of "talents" in man, and, like myself, comes to the conclusion that they could not be developed under the law of natural selection. He says: "It may be objected that, in man, in addition to the instincts inherent in every individual, special individual predispositions are also found, of such a nature that it is impossible they can have arisen by individual variations of the germ-plasm. On the other hand, these predispositions--which we call talents--cannot have arisen through natural selection, because life is in no way dependent on their presence, and there seems to be no way of explaining their origin except by an assumption of the summation of the skill attained by exercise in the course of each single life. In this case, therefore, we seem at first sight to be compelled to accept the transmission of acquired characters." Weismann then goes on to show that the facts do not support this view; that the mathematical, musical, or artistic faculties often appear suddenly in a family whose other members and ancestors were in no way distinguished; and that even when hereditary in families, the talent often appears at its maximum at the commencement or in the middle of the series, not increasing to the end, as it should do if it depended in any way on the transmission of acquired skill. Gauss was not the son of a mathematician, nor Handel of a musician, nor Titian of a painter, and there is no proof of any special talent in the ancestors of these men of genius, who at once developed the most marvellous pre-eminence in their respective talents. And after showing that such great men only appear at certain stages of human development, and that two or more of the special talents are not unfrequently combined in one individual, he concludes thus--

"Upon this subject I only wish to add that, in my opinion,
talents do not appear to depend upon the improvement of any
special mental quality by continued practice, but they are the
expression, and to a certain extent the bye-product, of the
human mind, which is so highly developed in all directions."

It will, I think, be admitted that this view hardly accounts for the existence of the highly peculiar human faculties in question.]

[Footnote 237: For an earlier discussion of this subject, with some wider applications, see the author's _Contributions to the Theory of Natural Selection_, chap. x.]

INDEX

=A=

Abbott, Dr. C.C., instability of habits of birds, 76
on American water-thrushes (Seiurus), 117
Mr., drawings of caterpillars and their food plants, 203

Accessory plumes, development and display of, 293

Acclimatisation, 94

Achatinellidae, Gulick on variations in, 147

Acquired characters, non-heredity of, 440

Acraeidae, mimicry of, 247

Adaptation to conditions at various periods of life, 112

Adolias dirtea, sexual diversity of, 271

Aegeriidae, mimicry by, 240

Agaristidae, mimicry of, 246

Agassiz, on species, 5
on North American weeds, 15.

Agelaeus phoeniceus, diagram showing variations of, 56;
proportionate numbers which vary, 64

Albatross, courtship of great, 287

Allen, Mr. Grant, on forms of leaves, 133
on degradation of wind-fertilised from insect-fertilised flowers,
325 (note)
on insects and flowers, 332
on production of colour through the agency of the colour sense, 334
Mr. J.A., on the variability of birds, 50

Allen, Mr. J.A., on colour as influenced by climate, 228

Alluring coloration, 210

American school of evolutionists, 420

Anemone nemorosa, variability of, 78

Animal coloration, a theory of, 288
general laws of, 296
intelligence, supposed action of, 425
characteristics of man, 454

Animals, the struggle among, 18
wild, their enjoyment of life, 39
usually die painless deaths, 38
constitutional variation of, 94
uses of colours of, 134
supposed effects of disuse in wild, 415
most allied to man, 450

Antelopes, recognition marks of, 219

Anthrocera filipendula inedible, 235

Apples, variations of, 87

Arctic animals, supposed causes of white colour of, 191

Argyll, Duke of, on goose reared by a golden eagle, 75

Artemia salina and A. milhausenii, 426

Asclepias curassavica, spread of, 28

Asses running wild in Quito, 28

Attractive fruits, 306

Australia, spread of the Cape-weed in, 29
fossil and recent mammals of, 392

Azara, on cause of horses and cattle not running wild in Paraguay, 19

Azores, flora of, supports aerial transmission of seeds, 368

=B=

Baker, Mr. J.G., on rarity of spiny plants in Mauritius, 432

Ball, Mr., on cause of late appearance of exogens, 400

Barber, Mrs., on variable colouring of pupae of Papilio nireus, 197
on protective colours of African sun-birds, 200

Barbs, 91

Barriers, importance of, in questions of distribution, 341

Bates, Mr. H.W., on varieties of butterflies, 44
on inedibility of Heliconidae, 234
on a conspicuous caterpillar, 236
on mimicry, 240, 243, 249

Bathmism or growth-force, Cope on, 421

Beddard, Mr. F.E., variations of earthworms, 67
on plumes of bird of paradise, 292

Beech trees, aggressive in Denmark, 21

Beetle and wasp (figs.), 259

Beetle, fossil in coal measures of Silesia, 404

Beginnings of important organs, 128

Belt, Mr., on leaf-like locust, 203
on birds avoiding Heliconidae, 234

Belt's frog, 266

Birds, rate of increase of, 25
how destroyed, 26
variation among, 49
variation of markings of, 52
variation of wings and tails of, 53
diagram showing variation of tarsus and toes, 60
use of structural peculiarities of, 135
eggs, coloration of, 212
recognition marks of, 222
and butterflies, white in tropical islands, 230
sometimes seize inedible butterflies, 255
mimicry among, 263

Birds, sexual coloration of, 275
cause of dull colour of female, 277
choice of female not known to be determined by colour, etc., 285
decorative plumage of, 285
antics of unornamented, 287
which fertilise flowers, 319
colours of, not dependent on the colours of flowers, 336
no proof of aesthetic tastes in, 336
dispersal of, 355
and insects at sea, 357
of oceanic islands, 358
carrying seeds on their feet, 361
ancestral forms of, 407

Birthplace, probable, of man, 459

Bombyx regia, protective form of larva of, 210

Boyd Dawkins, on development of deer's horns, 389
on origin of man, 456

Brady, Mr. George, on protective colouring of starfishes, 209

Brain development, progressive, 390

Brains of man and apes, 452

Branner, Mr. J.C., on supposed proofs of glaciation in Brazil, 370

Brazil, supposed proof of glaciation in, 370

Brewer, Professor W.H., on want of symmetry in colours of animals, 217

Bromelia, animals inhabiting leaves of, 118

Bronn, Professor, on supposed uselessness of variations of ears
and tails, 136

Butler, Mr. A.G., on inedibility of conspicuous caterpillars, 237

Butterflies, varieties of, 44
small, of Isle of Man, 106
special protective colouring of, 206
recognition by, 226
inedibility of some, 234
mimicry among, 240, 249
colour development of, 274
sexual coloration of, 271

=C=

Caddis-fly larvae inhabiting bromelia leaves, 118

Callophis, harmless mimicking poisonous species, 262

Candolle, Alp. de, on variation in oaks, 77
on variability of Papaver bracteatum, 79

Cardinalis virginianus, diagram showing proportionate numbers
which vary, 65;
variations of, 58

Carpenter, Dr. W.B., on variation in the Foraminifera, 43

Carriers, 91

Caterpillars, resemblance of, to their food plants, 203-205
inedible, 236

Cattle, how they prevent the growth of trees, 18
increase of, in St. Domingo, Mexico, and the pampas, 27

Ceylon, spread of Lantana mixta in, 29

Chaffinch, change of habit of, in New Zealand, 76

Chambers, Robert, on origin of species, 3

Chance rarely determines survival, 123

Change of conditions, utility of, 326

Characters, non-adaptive, 131
transferred from useless to useful class, 132

Charaxes psaphon persecuted by a bird, 235

Chile, numerous red tubular flowers in, 320

Chimpanzee, figure of, 454

Clark, Mr. Edwin, on cause of absence of forests on the pampas, 23
on the struggle for life in the South American valleys, 24

Cleistogamous flowers, 322

Close interbreeding, supposed evil results of, 326

Clover, white, spread of, in New Zealand, 28

Co-adaptation of parts by variation, no real difficulty, 418

Cobra, use of hood of, 262

Coccinella mimicked by grasshopper, (figure), 260

Collingwood, Mr., on butterflies recognising their kind, 226

Coloration, alluring, 210
of birds' eggs, 212
a theory of animal, 288

Colour correlated with sterility, 169
correlated with constitutional peculiarities, 170
in nature, the problem to be solved, 188
constancy, in animals indicates utility, 189
and environment, 190
general theories of animal, 193
animal, supposed causes of, 193
obscure, of many tropical animals, 194
produced by surrounding objects, 195
adaptations, local, 199
for recognition, 217
of wild animals not quite symmetrical, 217 (note)
as influenced by locality or climate, 228
development in butterflies, 274
more variable than habits, 278
and nerve distribution, 290
and tegumentary appendages, 291
of flowers, 308
change of, in flowers when fertilised, 317
in nature, concluding remarks on, 299, 333
of fruits, 304
of flowers growing together contrasted, 318

Complexity of flowers due to alternate adaptation to insect
and self-fertilisation, 328

Composite, a, widely dispersed without pappus, 367

Confinement, affecting fertility, 154

Continental and oceanic areas, 346

Continents and oceans cannot have changed places, 345
possible connections between, 349

Continuity does not prove identity of origin, 463

Cope, Dr. E.D., on non-adaptive characters, 131
on fundamental laws of growth, 420
on bathmism or growth-force, 421
on use producing structural change, 422
on law of centrifugal growth, 422
on origin of the feet of ungulates, 423
on action of animal intelligence, 425

Correlations in pigeons, horses, etc., 140

Corvus frugilegus, 2
corone, 2

Coursers, figures of secondary quills, 224

Cowslip, two forms of, 157

Crab, sexual diversity of colour of, 269

Cretaceous period, dicotyledons of, 400

Crisp, Dr., on variations of gall bladder and alimentary canal, 69

Crosses, a cause of variation, 99
reciprocal, 155

Cross-fertilisation, modes of securing, 310
difference in, 155

Crossing and changed conditions,
parallelism of, 166

Cruciferae, variations of structure in, 80

Cuckoo, eggs of, 216

Cuckoos mimick hawks, 263

Cultivated plants, origin of useful, 97

Curculionidae mimicked by various insects (figs.), 260

Curves of variation, 64

=D=

Dana, Professor, on the permanence of continents, 342

Danaidae little attacked by mites, 235
mimicry of, 246

Darwin, change of opinion effected by, 8
the Newton of Natural History, 9
his view of his own work, 10
on the enemies of plants, 16
on fir-trees destroyed by cattle, 17
on change of plants and animals caused by planting, 18
on absence of wild cattle in Paraguay, 19
on cats and red clover, 20
on variety of plants in old turf, 35
on the beneficent action of the struggle for existence, 40
on variability of wild geraniums, 79
on variability of common species, 80
his non-recognition of extreme variability of wild species, 82
on races of domestic pigeon, 90
on constitutional variation in plants, 95
on unconscious selection, 96
on a case of divergence, 105
on advantage of diversification of structure in inhabitants
of one region, 110
on species of plants in turf, 110
on isolation, 119
on origin of mammary glands, 129
on eyes of flatfish, 129
on origin of the eye, 130
on useless characters, 131
on use of ears and tails, 136
on disappearance of sports, 140
on tendency to vary in one direction, 141
on rare perpetuation of sports, 142
on utility of specific characters, 142 (note)
on importance of biological environment, 148
on variable fertility of plants, 155
on fertile hybrids among plants, 164

Darwin, on correlation of sterility and colour, 169
on selective association, 172
on infertility and natural selection, 174
on cause of infertility of hybrids, 185
on white tail of rabbit, 218
on conspicuous caterpillars, 236
on sexual selection in insects, 274
on decorative plumage of male birds, 285
on development of ocelli, 290
on value of cross-fertilisation, 309
on limits to utility of intercrossing, 326
on flowers due to insects, 332
on oceanic islands, 342
on effects of disuse in domestic animals, 415, 435
on direct action of environment, 419
on unintelligibility of theory of retardation and acceleration,
421 (note)
on origin of man's moral nature, 461
Mr. George, on intermarriages of British aristocracy, 326

Darwinian theory, statement of, 10 not opposed to spiritual nature of man, 478 Dawkins, Professor Boyd, on development of deer's horns, 389 on recent origin of man, 456 Dawson, Sir W., on determination of fossil plants by leaves, 398 (note)

Death of wild animals usually painless, 38

De Candolle, definition of species, 1
on difficulty of naturalising plants, 15
on war between plants, 16
on origin of useful cultivated plants, 97

Deer's horns, development of, 389

Degeneration, 121

Delboeuf's law of variation, 141

Dendraeca coronata, variation of wing-feathers of, 51

Denmark, struggle between trees in, 20

Denudation, evidences of, 379

Desert animals, colour of, 192

Deserts, effect of goats and camels in destroying vegetation in, 17

Development and display of accessory plumes, 293

Diadema anomala, 271
misippus, great diversity of sexes in, 271

Diaphora mendica mimics Spilosoma menthrasti, 249

Difficulties in the facts of fertilisation of flowers, 325

Dimorphism and trimorphism, 156

Dippers, probable origin of, 116

Disease and markings, 290

Diseases common to man and animals, 449

Display of decorative plumage, 287

Distribution of organisms should be explained by theory of descent, 338
conditions which have determined the, 341
of marsupials, 350
of tapirs, 352

Disuse, effects of, among wild animals, 415
no proof that the effects of, are inherited, 417

Divergence of character, 105-109
leads to maximum of forms of life in each area, 109

Diversity of fauna and flora with geographical proximity, 339

Dixon, Mr. C, changed habits of chaffinch in New Zealand, 76

Dogs, origin of, 88
varieties of, 89

Dolichonyx oryzivorus, diagram showing variations of, 55

Domestic animals, varieties of, 88

Draba verna, varieties of, 77

Dress of men not determined by female choice, 286

Dust from Krakatoa, size of particles of, 363

=E=

Eastern butterflies, variation of, 45

Eaton, Rev. A.E., on Kerguelen insects, 106

Edwards, Mr. W.H., on dark forms of Papilio turnus, 248

Eggs protectively coloured, 214, 215
theory of varied colours of, 216

Elaps mimicked by harmless snakes, 261

Embryonic development of man and other mammalia, 448

Ennis, Mr. John, on willows driving out watercresses from
rivers of New Zealand, 24

Entomostraca, in bromelia leaves, 118

Environment never identical for two species, 149
direct action of, 418
direct influence of, 426
as initiator of variations, 436
action of, overpowered by natural selection, 437

Ethical aspect of the struggle for existence, 36

Euchelia jacobeae inedible, 235

Everett, Mr. A., on a caterpillar resembling moss, 205

Evidence of evolution that may be expected among fossil forms, 380

Evolutionists, American school of, 420

Exogens, possible cause of sudden late appearance of, 400

External differences of man and apes, 453

Extinct animals, number of species of, 376

Extinction of large animals, cause of, 394

Eye, origin of, 130

Eyes, explanation of loss of in cave animals, 416

=F=

Facts of natural selection, summary of, 122

Falcons illustrating divergence, 108
and butcher birds, hooked and toothed beaks of, 422

Fantails, 91

Female birds, why often dull coloured, 277

Female birds, what their choice of mates is determined by, 286
butterflies, why dull coloured, 272
brighter than male bird, 281
choice a doubtful agent in selection, 283
preference neutralised by natural selection, 294

Fertility of domestic animals, 154

Flatfish, eyes of, 129

Flesh-fly, enormous increase of, 25

Floral structure, great differences of, in allied genera and species, 329

Flowers, variations of, 88
colours of, 308
with sham nectaries, 317
changing colour when fertilised, 317
adapted to bees or to butterflies, 318
contrasted colours of, at same season and locality, 318
fertilisation of, by birds, 319
self-fertilisation of, 321
once insect-fertilised now self-fertile, 323
how the struggle for existence acts among, 328
repeatedly modified during whole Tertiary period, 331
the product of insect agency, 332

Forbes, Mr. H.O., on protective colour of a pigeon, 200
on spider imitating birds' dropping, 211

Fossil shells, complete series of transitional forms of, 381
crocodiles afford evidence of evolution, 383
horses in America, 386
and living animals, local relations of, 391

Fowl, early domestication of, 97

Frill-back, Indian, 93

Frog inhabiting bromelia leaves, 118

Fruits, use of characters of, 133
colours of, 304
edible or attractive, 306
poisonous, 307

Fulica atra, protectively coloured eggs of, 215

Fulmar petrel, abundance of, 30

=G=

Gallinaceae, ornamental plumes of, 292

Galton, Mr. F., diagrams of variability used by, 74
on markings of zebra, 220 (note)
on regression towards mediocrity, 414
theory of heredity by, 443 (note)
on imperfect counting of the Damaras, 464

Gaudry on extinct animals at Pikermi, 377

Gay, Mons. T., on variations of structure in Cruciferae, 80

Gazella soemmerringi (figure), 219

Gazelles, recognition marks of, 218

Geddes, Professor, on variation in plants, 428
objection to theory of, 430

Geikie, Dr. Archibald, on formation of marine stratified rocks, 344

Geoffroy St. Hilaire, on species, 6

Geological evidences of evolution, 376, 381
record, causes of imperfection of, 379
distribution of insects, 403
antiquity of man, 455

Ghost-moth, colours of, 270

Glaciation, no proofs of, in Brazil, 370

Glow-worm, light a warning of inedibility, 287

Gomphia oleaefolia, variability of, 79

Goose eating flesh, 75

Gosse, Mr. P.H., on variation in the sea-anemones, 43
on sea-anemone and bullhead, 265

Gould, Mr., on colours of coast and inland birds, 228

Grant Allen, on forms of leaves, 133
on insects and flowers, 332

Graphite in Laurentian implies abundant plant life, 398

Gray, Dr. Asa, on naturalised plants in the United States, 110
Dr. J.E., on variation of skulls of mammalia, 71

Great fertility not essential to rapid increase, 30

Great powers of increase of animals, 27

Green colour of birds in tropical forests, 192

Grouse, red, recent divergence of, 106

Gulick, Rev. J.T., on variation of land-shells, 43
on isolation and variation, 147, 150
on divergent evolution, 148

=H=

Habits of animals, variability of, 74

Hairy caterpillars inedible, 237

Hanbury, Mr. Thomas, on a remarkable case of wind
conveyance of seed, 373 (note)

Hansten-Blangsted, on succession of trees in Denmark, 21

Harvest mice, prehensile tails of young, 136

Hawkweed, species and varieties of British, 77

Hector, Sir James, use of horns of deer, 137

Heliconidae, warning colours of, 234
mimicry of, 240

Helix nemoralis, varieties of, 43
hortensis, varieties of, 43

Hemsley, Mr., on rarity of spines in oceanic islands, 432

Henslow, Professor G., on vigour of self-fertilised plants, 323
on wind-fertilised as degradations from insect-fertilised flowers, 324
on origin of forms and structures of flowers, 434 (note)

Herbert, Dean, on species, 6
on plant hybrids, 164

Herbivora, recognition marks of, 218

Heredity, 11
Weismann's theory of, 437

Herschel, Sir John, on species, 3

Hooker, Sir Joseph, on attempts at naturalising Australian
plants in New Zealand, 16

Home, Mr. C, on inedibility of an Indian locust, 267

Horns of deer, uses of, 136

Horse tribe, pedigree of, 384
ancestral forms of, 386

Humming-birds, recognition marks of, 226

Huth, Mr., on close interbreeding, 160

Huxley, Professor on the struggle for existence, 37
on fossil crocodiles, 383
on anatomical peculiarities of the horse tribe, 384
on development of vertebrates, 448
on early man, 456
on brains of man and the gorilla, 457

Hybridity, remarks on facts of, 166
summary on, 184

Hybrids, infertility of, supposed test of distinct species, 152
fertility of, 159
fertile among animals, 162
between sheep and goat, 162
fertile between distinct species of moths, 163
fertile among plants, 163

Hymenopus bicornis, resembling flower, 212

=I=

Icterus Baltimore, diagram showing proportionate numbers which vary, 63

Imitative resemblances, how produced, 205

Increase of organisms in a geometrical ratio, 25

Inedible fruits rarely coloured, 308

Insect and self-fertilisation, alternation of, in flowers, 328

Insect-fertilisation, facts relating to, 316

Insects, coloured for recognition, 226
warning colours of, 233
sexual coloration of, 269
importance of dull colours to female, 272
visiting one kind of flower at a time, 318
and flowers, the most brilliant not found together, 335

Insects, no proof of love of colour by, 336
and birds at sea, 357
in mid-ocean, 359
at great altitudes, 360
geological distribution of, 403
ancestral in Silurian, 405
fossil support evolution, 405

Instability of useless characters, 138

Instinct, the theory of, 441

Insular organisms illustrate powers of dispersal, 354

Interbreeding, close, injurious effects of, 160
supposed evil results of close, 326

Intercrossing, swamping effects of, 142
not necessarily useful, 325

Intermediate forms, why not found, 380

Islands, all oceanic are volcanic or coralline, 342

Isle of Man, small butterflies of, 106

Isolation, the importance of, 119
to prevent intercrossing, 144
by variations of habits, etc., 145
Rev. J.G. Gulick on, 147
when ineffective, 150

Ituna Ilione and Thyridia megisto, figures of wings of, 251

=J=

Jacobin, 93

Jenyns, Rev. L., on internal variations of mammalia, 69

Jordan, Mons. A., on varieties of Draba verna, 77

Judd, Professor, on dust fallen at Genoa, 363
on Hungarian fossil lacustrine shells, 381

=K=

Kerguelen Island, wingless insects of, 106

Kerivoula picta, protective colour of, 201

Kerner, Professor, on use of external characters of plants, 133
on seeds found on glaciers, 366

Kingfishers illustrating divergence of character, 109

=L=

Lacerta muralis, diagram of variation of, 47

Lagopus scoticus, origin of, 107

Lamarck, on origin of species, 3

Land debris deposited near coasts, 343
and ocean, diagram showing comparative height and depth of, 345

Large animals, cause of extinction of, 394

Larvae of moths, variability of, 46

Laughers, Frill-backs, Nuns, Spots, and Swallows, 93

Law of relation of colour and nest, 278, 279

Laws of animal coloration, 296

Lawson Tait, on uses of tails, 136

Leaf-butterflies, 207

Leguminosae, rare in oceanic islands, 368

Lemuria, an unsound hypothesis, 354

Lepidoptera, variation of, 44

Leyden Museum, diagram showing variability of birds in, 61

Life, Weismann on duration of, 437 (note)

Limenitis misippus mimics Danais archippus, 248
ursula mimics Papilio philenor, 248

Linnaeus, on rapid increase of the flesh-fly, 25

Livingstone, his sensations when seized by a lion, 38

Lizards, variation among, 46
diagram of variation of, 48
sexual colours of, 281

Local colour adaptations, 199

Locusts with warning colours inedible, 267

Longicorns mimic Malacoderms, 257

Low, Mr., on effects of close interbreeding, 160

Low, Mr., on fertile crosses between sheep and goat, 162
on selective association, 172

Low forms of life, continued existence of, explained, 114
forms, persistence of, 121
temperature of tropics not needed to explain plant dispersal, 370

Lower types, extinction of, among the higher animals, 114

Lubbock, Sir John, on forms of leaves, 133
on imperfect counting of early man, 464

Lyell, Sir Charles, on variation of species, 4
on the shifting of continents, 342

=M=

Madagascar and New Zealand, 347

Madeira, wingless beetles of, 105

Maize, origin of, 98

Male rivalry, a real cause of selection, 283

Males of many animals fights together, 282

Malm, on eyes of flatfish, 129

Mammalia, variation of, 65
sexual colours of, 281, 282
afford crucial tests of theories of distribution, 353
early forms of, 407
geological distribution of, 408

Mammary glands, supposed origin of, 129

Man, summary of animal characteristics of, 454
geological antiquity of, 455
early remains of, in California, 456
probably as old as the Miocene, 457
probable birthplace of, 459
origin of moral and intellectual nature of, 461
possesses mental qualities not derived exclusively
from his animal progenitors, 474

Man's body that of an animal, 444
development similar to that of animals, 449
structure compared with that of the anthropoid apes, 451

Mania typica refused by lizards, 238

Mantidae resembling flowers, 212

Marcgravia nepenthoides fertilised by birds (woodcut), 320

Marine animals, protective resemblance among, 208
with warning colours, 266

Marsh, Mr., on destructiveness to vegetation of goats and camels, 17
Professor O., on the development of the horse tribe, 386
on brain development of Tertiary mammals, 391
on specialised forms dying out, 395

Marsupials, distribution of, 350

Mathematical faculty, the origin of the, 464
how developed, 466
not developed by law of natural selection, 469

Mathematics, late development of, 465

Meldola, Professor R., on variable protective colouring, 196
on mimicry among British moths, 249 (note)
on an extension of the theory of mimicry, 255 (note)

Melons, variations of, 87

Methona psidii and Leptalis orise (figs.), 241

Meyer, Dr. A.B., on mimicry of snakes, 262

Milne Edwards, on variation of lizards, 46

Mimicking birds deceive naturalists, 264
butterfly, figure of, 241

Mimicry, 239
how it has been produced, 242
among protected genera, 249
extension of, 255
in various orders of insects, 257
among vertebrata, 261
among birds, 263
objections to theory of, 264

Mineral particles carried by wind, 363

Miocene fossils of North America, 378

Missing links, character of, 380

Mivart, Dr. St. George, on variation of ribs and dorsal vertebrae, 69
on supposed useless characters, 138 (note)
on resemblance of man and apes, 451

Modifications for special purposes, 113

Mongrels, sterility of, 165

Monkeys affected by medicines as are men, 450

Monocotyledons degradations from dicotyledons, 325 (note)
scarcity of, in Rocky Mountains, 401
scarcity of, in Alpine flora, 401

Moral nature of man, origin of, 461

Morse, Professor E.T., on protective colouring of marine mollusca, 209

Moseley, Professor, on protective resemblance among marine animals, 208 on courtship of Great Albatross, 287

Moths, protected groups of, 235

Mountains, remote, with identical plants, 369

Müller, Dr. Fritz, on inhabitants of bromelia leaves, 118
on butterfly, deceived by its mimic, 245
his explanation of mimicry among protected genera, 252
Dr. Hermann, on variability of Myosurus minimus, 78

Murray, Mr. John, on bulk of land and ocean, 344
on quartz particles on ocean floor, 363
Rev. R.P., variation in the neuration of butterflies' wings, 45

Musical and artistic faculties, origin of, 467

Myosurns minimus, variability of, 78

=N=

Natural selection with changed and unchanged conditions, 103
and sterility, 173
overpowers effects of use and disuse, 435
the most important agency in modifying species, 444

Naturalist deceived by a mimicking insect, 259
by mimicking birds, 264

Naudin, M., on varieties of melons, 87

Nectarinea amethystina, protective colouring of, 201

Nestor notabilis, variation of habits of, 75

Nests of birds influence the colour of females, 278

New species, conditions favourable to origin of, 115

Newton, Professor A., on fertile hybrid ducks, 162

New Zealand, European plants in, 15
spread of white clover in, 28
effects of introduced plants in, 29
native rat and fly exterminated by European species, 34
many plants of, incapable of self-fertilisation, 321
fauna of, 348
few spiny plants in, 433

Nocturnal animals, colours of, 193

Non-adaptive characters, instability of, 138

Normandy pigs, fleshy appendages to jaws of, 139

North America, Miocene fossils of, 378

Northern plants in southern hemisphere, 368

Nostus Borbonicus, variability of, 80

Number of individuals which vary, 62

Nutmeg, how dispersed, 307

Nuts, not meant to be eaten, 305

=O=

Oaks, great variability of, 78

Objections to Darwin's theory, 126

Ocean floor, deposits on, 343

Oceanic animals, colours of, 193
and continental areas, 346
islands have no mammals or batrachia, 342

Oceans, the permanence of, 341

Oedicnemus, figures of wings of, 223

Opthalmis lincea and Artaxa simulans (figs.), 247

Orang-utans, variations of skull of, 69

Orchideae, why scarce on oceanic islands, 367

Orchis pyramidalis, mode of fertilisation of, 314
figures illustrating fertilisation of, 315

Organic development, three stages of, involving new cause or power, 474
world, the development of, implies a spiritual world, 476

Organisation, advance of, by natural selection, 120
degradation in, 121

Origin of species, objections, 7
of accessory plumes, 291

Orioles mimicking honey-suckers, 263

Ornamental plumes and vitality, 293

=P=

Pachyrhynchi subjects of mimicry, 261

Pampas, effects of drought in, 23

Papaver bracteatum, variability of, 79

Papilio, use of forked tentacle of larva of, 210
protected groups of, 235
mimicry of, 247

Paraguay, absence of wild cattle and horses, 19

Parnassia palustris, sham nectaries of, 317

Parrot, change of habits of New Zealand, 75

Parus, species of, illustrate divergence, of character, 107

Passenger-pigeon, account of its breeding-places and numbers, 31

Pelagic animals, colours of, 193

Phasmidae, resemblance of, to sticks and leaves, 203

Physiological selection, 180

Pickard-Cambridge, Rev. O., on sexual selection, 296 (note)

Pieridae, sexual diversity among, 271

Pigeons, varieties of, 89
domestic, derived from wild rock-pigeons, 90
curious correlations in, 140
white eggs of, protective, 213

Pigs, great increase of, in South America and New Zealand, 28

Pikermi, extinct animals of, 377

Pipits as illustrating divergence, 108

Planorbidae, variations of, 44

Plants, the enemies of, 16
variability of, 76
constitutional variation of, 94
colour relations of, 302
true mimicry rare in, 303
exotic rarely naturalised in Europe, 356
dispersal of, 361
northern, in southern hemisphere, 368
identical on summits of remote mountains, 369
progressive development of, 397
geological development of (diagram), 402

Plovers, recognition marks of (figure), 221

Plumes, origin of accessory, 291
muscular relation of ornamental, 292

Poisonous fruits, 307

Porto Santo, rabbits of, 326

Poulton, Mr. E.B., on variable colours of larvae and pupae, 196, 198
on concealments of insects by resemblance to environment, 202
on protective form of Notodonta ziczac, 210
on inedibility of conspicuous larvae, 237

Pouters, 90

Primulaceae, variations of structure in, 79

Problem, the, before Darwin, 6

Problems in variation and heredity, 410

Progression in plants and animals, 395

Protection by terrifying enemies, 209

Protective colouring, variable, 195
of white-headed fruit-pigeon, 200
of African sun-birds, 200
of Kerivoula picta, 201
of sloths, 201
of larva of Sphinx ligustri, 202
of stick and leaf insects, 203
of caterpillars, 203, 205
of butterflies, 206

Ptilopus cinctus, protective colour of, 200

Pugnacity of birds with accessory plumes, 294

=R=

Rabbit, use of white tail of, 218

Rapid increase of plants, 28

Raspail, M., on variability in a grass, 80

Rat, black, spread of, 34

Rattlesnake, use of rattle of, 262

Raven, why black in arctic regions, 191

Reciprocal crosses, 155

Recognition marks of herbivora, 218
of birds, 222
of tropical forest birds, 224
of insects, 226

Reproductive functions, susceptibility of, 153

Reptiles, geological distribution of, 406

Rhinoceroses, evidence of evolution afforded by fossil, 383

Rocks, all stratified formed in shallow water, 344

Rocky Mountains, scarcity of monocotyledons in, 401

Rodents, prevent woody vegetation in the pampas, 23

Romanes, Professor G.J., on useless characters, 131, 139
on meaningless peculiarities of structure, 140
on supposed absence of simultaneous variations, 142
on physiological selection, 180

Rook and crow, 2

Roses, Mr. Baker on varieties of, 77

Rubus, Bentham and Babington on species and varieties of, 77

Rudiments and variations in man, 446

Runts, 91

Rutaceae, variation of structure in, 79

=S=

St. Helena, destruction of forests by goats, 17

St. Hilaire, M. Aug., variability of Gomphia oleaefolia, 79

Saxicola, divergence of character in species of, 108
recognition marks of, 222

Scientific opinion before Darwin, 4

Scolopax, figures of tails of, 225

Scudder, Mr. S.H., on inedibility of Danais archippus, 238
on fossil insects, 403

Seebohm, Mr., on swamping effects of intercrossing, 143

Seeds, how dispersed, 306
how protected, 307
floating great distances, 361
dispersal of, by wind, 362
weight and dimensions of, 364
importance of wind-carriage of, 372
remarkable case of wind-carriage of, 373

Seiurus carolinensis, diagram of variation, 67
sp., habits of, 117

Selection, artificial, 84
by man, circumstances favourable to, 96
unconscious, 96

Selective association, isolation by, 171

Self-fertilisation of flowers, 321

Semper, Professor, on casting hairs of reptiles and Crustacea, 137 (note)
on direct influence of environment, 426

Sesiidae, mimicry by, 240

Sex colour and nests of birds, 277

Sex, colours characteristic of, 269

Sexual colours of insects, probable causes of, 273
of birds, 275
characters due to natural selection, 283
diversity the cause of variation, 439

Sexual selection and colour, 274
by struggles of males, 282
neutralised by natural selection, 294-296
restricted to male struggles, 296

Shetland Islands, variety of ghost-moth in, 270

Shrews and field-mice, internal variations of, 69

Shrikes, recognition marks of, 222

Similarity of forms of life not due to similarity of conditions, 339

Singing of male birds, use of, 284

Skull of wolf, diagram of variations of, 70
of Ursus labiatus, diagram of variations of, 72
of Sus cristatus, diagram of variations of, 73

Skunk an illustration of warning colour, 233

Slack, Baron von, on protective markings of sloths, 201

Sloth, protective colour and marking of, 201

Snakes, mimicry of poisonous, 261

Snipe, tails of two species (figs.), 225

Sounds and odours peculiar to male,
how useful, 284
produced by peculiar feathers, 284

South America, fossil and recent mammals of, 393

Species, definition of, 1, 2
origin of, 2, 6
Lyell on, 4
Agassiz on, 5
transmutation of, 6
Geoffroy St. Hilaire on, 6
Dean Herbert on, 6
Professor Grant on, 6
Von Buch on, 6
allied, found in distinct areas, 36

Species, which vary little, 80
closely allied inhabit distinct areas, 111
vigour and fertility of, how kept up, 327

Spencer, Mr. Herbert, on factors of organic evolution, 411
on effects of disuse, 413
on difficulty as to co-adaptation of parts, 417
on direct action of environment, 418