The Black Sleep.

Set in England in 1872, the story concerned a prominent, knighted surgeon whose wife has fallen into a coma caused by a deep-seated brain tumor. He undertakes to secretly experiment on the brains of living, but involuntary, human subjects who are under the influence of a powerful Indian anesthetic, Nind Andhera, which he calls the "Black Sleep" Once he has finished his experiment, surviving subjects are revived and placed in seriously degenerated and mutilated states.