Back in the 1950s, Galaxy Science Fiction began a series of reprint paperback novels which they gave away with issues of the magazine. After 35 issues, the novel series was sold to Beacon Books, who were known for publishing mildly pornographic romance paperbacks. As a result, the Galaxy novels issued by Beacon were "edited" to add sexual content.
I first came across these books when I learnt of The Mating Cry, a variant of one of my favourite sf novels, AE van Vogt's The Undercover Aliens. So I tracked down a copy and read it. It made for a somewhat bizarre reading experience - I blogged about it here. I've subsequently picked up (most of) the others in the series at various conventions. I had the vague idea of reading them and the novels on which each one was based, and then comparing the two. To date, I've not really got started on it, for a couple of reasons: one, some of the original novels are difficult to find; and two, given the Beacon books' cover art, I've always felt they're a little too embarrassing to read during my daily commute.
The titles were:
Odd John, Olaf Stapledon (1959). This had already been published by Galaxy in 1952. As far as I'm aware, both editions were identical - i.e., the Beacon one was not "edited".
The Deviates, Raymond F Jones (1959). This was a spiced-up version of Jones's novel The Secret People. I have the Beacon one but not the original.
Troubled Star, George O Smith (1959), was originally published under the same title as a serial in Startling Stories in 1953, and later as a novel in 1957. The Beacon version had added sexual content. I've yet to find a copy of the original novel.
Pagan Passions, Laurence Janifer and Randall Garrett (1959), was, as far as I can determine, original to the Beacon series.
Virgin Planet, Poul Anderson (1960), was a spiced-up version of a novel of the same title published the year before.
Flesh, Philip José Farmer (1960), probably didn't need any sexual content adding. It was original to the Beacon series.
The Sex War, Sam Merwin, Jr (1960), was an expanded version of 'The White Widows', originally published in Startling Stories in 1953. A book version appeared the same year. I've not found a copy of the original novel yet.
A Woman a Day, Philip José Farmer (1960), was an expansion of 'Moth and Rust', originally published in Startling Stories in 1953. It has also been published as a novel with the titles The Day of Timestop and Timestop!. I have both versions, so I could do this one.
The Mating Cry, A.E. Van Vogt (1960), was a revised version of The House That Stood Still from 1950. It was later published as The Undercover Aliens. See here.
The Male Response, Brian Aldiss (1961), is another book which I think was original to the Beacon series.
Sin In Space, Cyril Judd (1961), is a spiced-up version of Outpost Mars. Although I've yet to read the Beacon edition, the original is a fairly ordinary tale of settlers on Mars, which might as well be set in any new town in the American Midwest. I really should get around to reading the Beacon version, so I can compare the two.