[in the scarce wrappers] Westminster: A. Constable and Co., 1894. Original grey wrappers lettered in dark blue.
First Edition, being the first volume in the publisher's ill-fated "Acme Library" (also issued in blue cloth). This is a suspenseful tale involving mesmeric trances and mind control; as G&G points out, Doyle's interest in the subject dated back to his days of medical practice in Southsea.
The chief characters are Dr. Austin Gilroy, a physiologist; Agatha, his fiancée; and Mrs. Penelosa, a medium with enormous mesmeric power. Gilroy, at first a skeptic, is working with Mrs. Penelosa on psychic research. He soon observes that she has fallen in love with him, although he feels no attraction to her. He also learns that not only can she mesmerize; she can also project her personality, possess others, and drive them to do what she wants. When Gilroy rejects her, she assaults him psychically and sets out to destroy him. He finds himself engaged in foolish and criminal acts, and loses his job... [Bleiler]
This short tale is especially noteworthy on two counts. First, it is a foreshadowing of Doyle's later conversion to spiritualism, the topic that consumed his later years. Second, the tale is also a foreshadowing of another book published by Constable three years later, dealing with a different type of possession: Bram Stoker's DRACULA (in fact, Constable then reissued THE PARASITE in yellow cloth lettered in red, à la DRACULA, to emphasize the similarity).
This copy is in the original grey wrappers (actually, plain card covers with a french-fold dust jacket); such copies are far scarcer than those in blue cloth. It is in very good-plus condition (minor chipping at the two bottom corners of the rear cover and at the foot of the spine). Green & Gibson A17a; Bleiler 552. Item #13452