Some things you just can't un-read.
However, with that in mind, I realized that I'm getting very close to finishing this period of my reading of genre precursor classics. By my estimation, here's what I have left (books that I don't have a copy of yet are marked with the *):
The Narrative of A. Gordon Pym, Edgar Allen Poe (1838)
Lud-in-the-Mist, Mirrlees (1926)
The Greatest Adventure, John Taine (1929)
*The Crystal Horde, John Taine (1930)
*The Time Stream, John Taine (1931)
*Before the Dawn, John Taine (1934)
Odd John, Olaf Stapledon (1935)
(Since they're bundled together, I'll also pick up Sirius by Stapledon, 1944)
Out of the Silent Planet, C. S. Lewis (1938)
After which I'll be able to head into the "Golden Age" with a clear conscience, probably starting with Lest Darkness Fall (L. Sprague De Camp, 1939) and Slan (A. E. van Vogt 1946).
Depending on how I find them, I may not read all four John Taine books. However, they were highly recommended to me by the late Charles Brown, so the plan is to read them all. None of them are terribly long.
It's really quite exciting to be so close to the end of this phase. With any luck I'll be done by the end of the year. I'm really looking forward to getting into the 50s and thence on to the New Wave. I think I may be close to ready for it now.