Some extracts:

Yet had I known such pain was in the next room, and had it been dumb, I believe […] I could have stood it well enough. It is when suffering finds a voice and sets our nerves quivering that this pity comes troubling us.

It may seem a strange contradiction in me […] but now, seeing the creature ([the leopard-man who we were hunting because he broke the law]) there in a perfectly animal attitude, with the light gleaming in its eyes and its imperfectly human face distorted with terror, I realised again the fact of its humanity.

Before, they had been beasts, their instincts fitly adapted to their surroundings, and happy as living things may be. Now they stumbled in the shackles of humanity, lived in a fear that never died, fretted by a law they could not understand; their mock-human existence, begun in an agony, was one long internal struggle, one long dread of Moreau–and for what? It was the wantonness of it that stirred me.