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Also, in a note (vol. i. p. 223), he speaks of incidental results of certain unknown differences in the constitution of the reproductive system.

Thus, then, it is admitted by our author that we may have abrupt, strongly marked' changes, neither beneficial nor injurious' to the creatures possessing them, produced by unknown agencies' lying deep in the nature or constitution of the organism,' and which, if acting uniformly, would probably 'modify similarly “all the individuals of a species. If this is not an abandonment of natural selection,' it would be difficult to select terms more calculated to express it. But Mr. Darwin's admissions of error do not stop here. In the fifth edition of his Origin of Species '(p. 104) he says, “Until reading an able and valuable article in the “ North British Review” (1867), I did not appreciate how rarely single variations, whether slight or strongly marked, could be perpetuated.' Again : he was formerly 'inclined to lay much stress on the principle of protection, as accounting for the less bright colours of female birds' (Descent of Man,' vol. ii. p. 198); but now he speaks as if the correctness of his old conception of such colours being due to protection was unlikely. “Is it probable,' he asks, that the head of the female chaffinch, the crimson on the breast of the female bullfinch, -the green of the female chaffinch,—the crest of the female golden-crested wren, have all been rendered less bright by the slow process of selection for the sake of protection ? I cannot think so' (vol. ii. p. 176.)

Once more Mr. Darwin shows us (vol. i. p. 125) how he has been over-hasty in attributing the development of certain structures to reversion. He remarks, “In my “ Variations of Animals under Domestication” (vol. ii. p. 57) I attributed the not very rare cases of supernumerary mammæ in women to reversion.' * But Professor Preyer states that mamme erraticæ have been known to occur in other situations, even on the back; so that the force of my argument is greatly weakened or perhaps quite destroyed.'

Finally, we have a postscript at the beginning of the second volume of the Descent of Man' which contains an avowal more remarkable than even the passages already cited. He therein declares:

'I have fallen into a serious and unfortunate error, in relation to the sexual differences of animals, in attempting to explain what seemed to me a singular coincidence in the late period of life at which the necessary variations have arisen in many cases, and the late period at which sexual selection acts. The explanation given is wholly

E 2

erroneous, other

erroneous, as I have discovered by working out an illustration in figures.'

While willingly paying a just tribute of esteem to the candour which dictated these several admissions, it would be idle to dissemble, and disingenuous not to declare, the amount of distrust with which such repeated over-hasty conclusions and erroneous calculations inspire us. When their Author comes before us anew, as he now does, with opinions and conclusions still more startling, and calculated in a yet greater degree to disturb convictions reposing upon the general consent of the majority of cultivated minds, we may well pause before we trust ourselves unreservedly to a guidance which thus again and again declares its own reiterated fallibility. Mr. Darwin's conclusions may be correct, but we feel we have now indeed a right to demand that they shall be proved before we assent to them; and that since what Mr. Darwin before declared must be,' he now admits not only to be unnecessary but untrue, we may justly regard with extreme distrust the numerous statements and calculations which, in the Descent of Man,' are avowedly recommended by a mere may be. This is the more necessary, as the Author, starting at first with an avowed hypothesis, constantly asserts it as an undoubted fact, and claims for it, somewhat in the spirit of a theologian, that it should be received as an article of faith. Thus the formidable objection to Mr. Darwin's theory, that the great break in the organic chain between man and his nearest allies, which cannot be bridged over by any extinct or living species, is answered simply by an appeal to a belief in the general principle of evolution" (vol. i. p. 200), or by a confident statement that ' have

every reason to believe that breaks in the series are simply the result of many forms having become extinct' (vol. i. p. 187). So, in like manner, we are assured that the early progenitors of man were, no doubt, once covered with hair, both sexes having beards; their ears were pointed and capable of movement; and their bodies were provided with a tail, having the proper muscles" (vol. i. p. 206). And, finally, we are told, with a dogmatism little worthy of a philosopher, that, unless we wilfully close our eyes,' we must recognise our parentage (vol. i. p. 213).

These are hard words; and, even at the risk of being accused of wilful blindness, we shall now proceed, with an unbiassed and unprejudiced mind, to examine carefully the arguments upon which Mr. Darwin's theory rests. Must we acknowledge that man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to

we

other men but to the humblest living creature, with his god-like intellect which has penetrated into the movements and constitution of the solar system,' must we acknowledge that man with all these exalted powers’ is descended from an Ascidian? Is this a scientific truth resting on scientific evidence, or is it to be classed with the speculations of a bygone age?

With regard to the Origin of Man, Mr. Darwin considers that both natural selection and sexual selection' have acted. We need not on the present occasion discuss the action of natural selection; but it will be necessary to consider that of sexual selection' at some length. It plays a very important part in the descent of man,' according to Mr. Darwin's views. He maintains that we owe to it our power of song and our hairlessness of body, and that also to it is due the formation and conservation of the various races and varieties of the human species. In this matter then we fear we shall have to make some demand upon our readers' patience. “Sexual selection' is the corner-stone of Mr. Darwin's theory. It occupies threefourths of his two volumes ; and unless he has clearly established this point, the whole fabric falls to the ground. It is impossible, therefore, to review the book without entering fully into the subject, even at the risk of touching upon some points which, for obvious reasons, we should have preferred to pass over in silence.

Under the head of sexual selection' Mr. Darwin includes two very distinct processes. One of these consists in the action of superior strength or activity, by which one male succeeds in obtaining possession of mates and in keeping away rivals. This is, undoubtedly, a vera causa ; but may be more conveniently reckoned as one kind of natural selection' than as a branch of • sexual selection. The second process consists in alleged preference or choice, exercised freely by the female in favour of particular males on account of some attractiveness or beauty of form, colour, odour, or voice, which such males may possess. It is this second kind of sexual selection' (and which alone deserves the name) that is important for the establishment of Mr. Darwin's views, but its valid action has to be proved.

Now, to prove the existence of such a power of choice Mr. Darwin brings forward a multitude of details respecting the sexual phenomena of animals of various classes ; but it is the class of birds which is mainly relied on to afford evidence in support of the exercise of this power of choice by female animals. We contend, however, that not only is the evidence defective even here, but that much of his own evidence is in direct opposition to his views. While the unquestionable fact, that male sexual characters (horns, mane,

wattles,

wattles, &c., &c.) have been developed in many cases where sexual selection has certainly not acted, renders it probable, à priori, that the unknown cause which has operated in these numerous cases has operated in those instances also which seem to favour the hypothesis supported by Mr. Darwin. Still he contends that the greater part of the beauty and melody of the organic world is due exclusively to this selective process, by which, through countless generations, the tail of the peacock, the throat of the humming-bird, the song of the nightingale, and the chirp of the grasshopper have been developed by females, age after age, selecting for their mates males possessing in a more and more perfect degree characters which must thus have been continually and constantly preferred.

Yet, after all, Mr. Darwin concedes in principle the very point in dispute, and yields all for which his opponents need argue, when he allows that beautiful and harmonious variations may occur spontaneously and at once, as in the dark or spangled bars on the feathers of Hamburgh fowls ( Descent of Man,' vol. i. p. 281). For what difference is there, other than mere difference of degree, between the spontaneous appearance of a few beautiful new feathers with harmonious markings and the spontaneous appearance of a whole beautiful clothing like that of the Tra

Again, on Mr. Darwin's own showing, it is manifest that male sexual characters, such as he would fain attribute to sexual selection, may arise without any such action whatever. Thus he tells us, “There are breeds of the sheep and goat, in which the horns of the male differ greatly in shape from those of the female;' and with tortoise-shell cats, the females alone, as a general rule, are thus coloured, the males being rusty-red' (vol. i. p. 283). Now, if these cats were only known in a wild state, Mr. Darwin would certainly bring them forward amongst his other instances of alleged sexual selection, though we now know the phenomenon is not due to any such cause. A more striking instance, however, is the following :-With the pigeon, the sexes of the parent species do not differ in any external character; nevertheless, in certain domesticated breeds the male is differently coloured from the female. The wattle in the English carrier-pigeon and the crop in the pouter are more highly developed in the male than in the female ;' and this has arisen, not from, but rather in opposition to, the wishes of the breeder ; which amounts to a positive demonstration that sexual characters may arise spontaneously, and, be it noted, in the class of birds.

The uncertainty which besets these speculations of Mr. Darwin is evident at every turn. What at first could be thought a

better

gopans?

better instance of sexual selection than the light of the glowworm, exhibited to attract her mate? Yet the discovery of luminous larvæ, which of course have no sexual action, leads Mr. Darwin to observe: 'It is very doubtful whether the primary use of the light is to guide the male to the female' (vol. i. p. 345). Again, as to certain British field-bugs, he says: 'If in any species the males had differed from the females in an analogous manner, we might have been justified in attributing such conspicuous colours to sexual selection with transference to both sexes' (vol. i.

P. 350). As to the stridulating noises of insects (which is assumed to be the result of sexual selection), Mr. Darwin remarks of certain Neuroptera :— It is rather surprising that both sexes should have the power of stridulating, as the male is winged and the female wingless' (vol. i. p. 366); and he is again surprised to find that this power is not a sexual character in many Coleoptera (vol. i. p. 382).

Moths and butterflies, however, are the insects which Mr. Darwin treats of at the greatest length in support of sexual selection. Yet even here he supplies us with positive evidence that in certain cases beauty does not charm the female. He tells us :

• Some facts, however, are opposed to the belief that female butterflies prefer the more beautiful males; thus, as I have been assured by several observers, fresh females may frequently be seen paired with battered, faded, or dingy males.'-vol. i. p. 400.

As to the Bombycidæ he adds :

• The females lie in an almost torpid state, and appear not to evince the least choice in regard to their partners. This is the case with the common silk-moth (B. mori). Dr. Wallace, who has had such immense experience in breeding Bombyx cynthia, is convinced that the females evince no choice or preference. He has kept above 300 of these moths living together, and has often found the most vigorous females mated with stunted males.'

Nevertheless, we do not find, for all this, any defect of colour or markings, for, as Mr. Alfred Wallace observes (Nature, March 15th, 1871, p. 182), 'the Bombyces are amongst the most elegantly coloured of all moths.'

Mr. Darwin gives a number of instances of sexual characters, such as horns, spines, &c., in beetles and other insects; but there is no fragment of evidence that such structures are in any way due to feminine caprice. Other structures are described and figured which doubtless do aid the sexual act, as the claws of certain Crustacea; but these are often of such size and strength (e. g. in Callianassa and Orchestia) as to render any power of

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