“Those who take the trouble to read the essays published in 1859
     and 1860, will, I think, do me the justice to admit that my zeal
     to secure fair play for Mr. Darwin did not drive me into the
     position of a mere advocate; and that, while doing justice to the
     greatness of the argument, I did not fail to indicate its weak
     points.  I have never seen any reason for departing from the
     position which I took up in these two essays; and the assertion
     which I sometimes meet with nowadays that I have ‘recanted’ or
     changed my opinions about Mr. Darwin’s views is quite
     unintelligible to me.

      “As I have said in the seventh essay, the fact of evolution is
     to my mind sufficiently evidenced by palaeontology; and I remain
     of the opinion expressed in the second, that until selective
     breeding is definitely proved to give rise to varieties infertile
     with one another, the logical foundation of the theory of natural
     selection is quite incomplete.  We still remain very much in the
     dark about the causes of variation; the apparent inheritance of
     acquired characters in some cases; and the struggle for existence
     within the organism, which probably lies at the bottom of both
     these phenomena.”—­(1893, Preface.)

Finally, when he was awarded the Darwin Medal of the Royal Society, on November 30, 1894, in the course of an address at the anniversary dinner of the Society, he said, as reported in the Times next day: 

“I am as much convinced now as I was thirty-four years ago that the theory propounded by Mr. Darwin, I mean that which he propounded—­not that which has been reported to be his by too many ill-instructed, both friends and foes—­has never yet been shewn to be inconsistent with any positive observations, and if I may use a phrase which I know has been objected to, and which I use in a totally different sense from that in which it was first proposed by its first propounder, I do believe that on all grounds of pure science it ‘holds the field’ as the only hypothesis at present before us which has a sound scientific foundation....  I am sincerely of opinion that the views which were propounded by Mr. Darwin thirty-four years ago may be understood hereafter as constituting an epoch in the intellectual history of the human race.  They will modify the whole system of our thought and opinion, our most intimate convictions.  But I do not know, I do not think anybody knows, whether the particular views he held will be hereafter fortified by the experience of the ages which come after us....  Whether the particular form in which he has put before us the Darwinian doctrines may be such as to be destined to survive or not, is more, I venture to think, than anybody is capable at this present moment of saying.”

Further details of Huxley’s relation to natural selection may be gained from an interesting chapter in Professor Poulton’s volume on Charles Darwin (Cassell and Co., London, 1896).