This article forms the second part of a piece on George Henry Lewes’s testimony at the 1875 Royal Commission on Vivisection. The first part established the background to his testimony, including the origins of his interests in experimental physiology, his scientific networking. and his distinctive role as the sole “private investigator” to testify at the Commission, at a time when amateur and private animal experimentation was under increasing scrutiny. This second part will offer a detailed breakdown of Lewes’s December 1875 testimony, exploring themes in the questions he was asked and providing further contextualization to his answers, including their links with his broader physiological theories, as previously published in his Physiology of Common Life and as he was further developing at the time in his Problems of Life and Mind book series. It will conclude by considering the aftermath of Lewes’s testimony and his legacy as a scientist.