Charles Darwin’s last book was about earthworms. The Formation of Vegetable Mould, Through the Action of Worms, With Observations on Their Habits, is a quirky and thoroughly charming read. “The subject has been to me a hobby-horse,” he wrote about the book, “and I have perhaps treated it in foolish detail.” He held candles up to earthworms to test them for sight, played the piano for them to see how they reacted to sound, and set out miniature taste tests of cabbage, mint, and onion to learn their culinary preferences.
I bought an 1897 edition of the book (it was published in 1881) for a mere forty bucks, and it served as a kind of inspiration while I was writing my book. The bargain price on that book just goes to show you how the Internet has changed book collecting. If I had to comb through bookstores looking for the book, it would have been a year before I found one—and the volume I did find in a bookstore was quite a bit more expensive. Of course, my copy is not in great shape—the leather is dried and cracking, the corners are crumbling—but it is a lovely old thing nonetheless.
There have been some paperback reprints, but most of the copies available online are quite old. Project Gutenberg has also made the book available online as an e-text (they welcome your donations, by the way, to continue this useful project.) Anyway, if you’re interesting in continuing your earthworm education, go right to the source and check out Darwin.