been imperceptibly rendered such as we now see them.” {105b} Who can doubt that accident is here regarded as a potent factor of evolution, as well as the design that is involved in the supposition that modification is, in the main, functionally induced?  Again he writes, “As regards the circumstances that give rise to variation, the principal are climatic changes, different temperatures of any of a creature’s environments, differences of abode, of habit, of the most frequent actions, and lastly of the means of obtaining food, self-defence, reproduction,” &c. {105c} I will not dwell on the small inconsistencies which may be found in the passages quoted above; the reader will doubtless see them, and will also doubtless see that in spite of them there can be no doubt that Lamarck, while believing modification to be effected mainly by the survival in the struggle for existence of modifications which had been induced functionally, would not have hesitated to admit the survival of favourable variations due to mere accident as also a potent factor in inducing the results we see around us.

For the rest, Mr. Spencer’s articles have relieved me from the necessity of going into the evidence which proves that such structures as a giraffe’s neck, for example, cannot possibly have been produced by the accumulation of variations which had their origin mainly in accident.  There is no occasion to add anything to what Mr. Spencer has said on this score, and I am satisfied that those who do not find his argument convince them would not be convinced by anything I might say; I shall, therefore, omit what I had written on this subject, and confine myself to giving the substance of Mr. Spencer’s most telling argument against Mr. Darwin’s theory that accidental variations, if favourable, would accumulate and result in seemingly adaptive structures.  Mr. Spencer well shows that luck or chance is insufficient as a motive-power, or helm, of evolution; but luck is only absence of design; if, then, absence of design is found to fail, it follows that there must have been design somewhere, nor can the design be more conveniently placed than in association with function.

Mr. Spencer contends that where life is so simple as to consist practically in the discharge of only one function, or where circumstances are such that some one function is supremely important (a state of things, by the way, more easily found in hypothesis than in nature—­at least as continuing without modification for many successive seasons), then accidental variations, if favourable, would indeed accumulate and result in modification, without the aid of the transmission of functionally produced modification.  This is true; it is also true, however, that only a very small number of species in comparison with those we see around us could thus arise, and that we should never have got plants and animals as embodiments of the two great fundamental principles on which it is alone possible that life can be conducted, {107a} and species of plants and animals as embodiments of the details involved in carrying out these two main principles.