https://mathcs.clarku.edu/huxley/

"Those merely interested in Huxley and scholars engaged in research on him, on Darwinism, on Victorian culture, on the history of science, and on topics such as those noted will find that THE HUXLEY FILE, in which reside over 1000 items, justifies its title. The 1000 figure covers 680 pieces of published and unpublished text by THH; more than 150 pictures by and on him, with an uncounted number of pictures in text by and for him; and 120 commentaries on him. Cybernauts will find here

• the entirety of the nine-volume Collected Essays;
• 40 selections from the five-volume Scientific Memoirs;
• and also a large number of Huxley essays that were never collected, from The Westminster Review, Youth's Companion, etc.; among these, the most important hidden pieces are the three essays he wrote for a club, The Metaphysical Society, on whether a frog has a soul, whether immortality is reasonable, whether Jesus was actually resurrected;
• several pieces that exist only in draft form, such as his teenage journal "Thoughts and Doings," "Agnosticism–A Fragment" and "The Natural History of Christianity";
• letters published in The Times, Nature, etc.; most of the letters appear in Leonard Huxley, ed., The Life and Letters of Thomas Huxley and Julian Huxley, ed., Thomas Henry Huxley's Diary of the Voyage of H.M.S. Rattlesnake –which is the best provider of THH's diary items; some of the letters come from collections in libraries around the world.
• a cornucopia of illustrations ranging from his doodles and sketches of natives to cartoons and portraits of him, illustrations not attached to any text, and a number illustrating texts such as Man's Place in Nature and Oceanic Hydrozoa.
• 120 commentaries on him, some praising his work, others attacking it, such as Powheads, Porwiggles and Protoplasm."