In 1869 he became a fellow of the Zoological Society of London, and in 1874 he was appointed by Thomas John Capel as Professor of Biology at the short-lived Catholic University College, Kensington, a post he held until 1877.

[6] Mivart met Thomas Henry Huxley in 1859, and was initially a close follower and a believer in natural selection.

"Even as a professor he continued to attending Huxley's lectures ... they became close friends, dining together and arranging family visits.

As to "natural selection", I accepted it completely and in fact my doubts & difficulties were first excited by attending Prof. Huxley's lectures at the School of Mines.

[7] Huxley,[8] Ray Lankester, and William Henry Flower had come out against his ideas, although O'Leary (2007) reports that "their initial reaction to Genesis of Species was tolerant and impersonal".

[9] Though admitting evolution in general, Mivart denied its applicability to the human intellect (a view also taken by Alfred Russell Wallace).

One of Mivart's criticisms to which Darwin responded was a perceived failure of natural selection to explain the incipient stages of useful structures.

In response, Darwin arranged for the reprinting of a pamphlet by Chauncey Wright, previously issued in the US, which severely criticised Genesis of Species.

[12]: 353–356 The quarrel reached a climax when Mivart lost his usual composure over what should have been a minor incident: In 1873, George Darwin (Charles' son) published a short article in The Contemporary Review suggesting that divorce should be made easier in cases of cruelty, abuse, or mental disorder.

In them, reversing his previous stance, he challenged the authority of the Church, concluding that the Bible and Catholic doctrine could not be reconciled with science.

However, Sir William Broadbent gave medical testimony that these could be explained by the gravity and nature of the diabetes from which he had suffered.