OT: A curious mystery of probably very little importance.

[dogscoff]

It's actually an intestinal parasite that infests the innards of the book and sucks away at its nutrients- a kind of tapeworm, (Taenia saginata librus) the so-called "bookworm". You'll probably notice that on the affected pages there are letters or even whole words missing, these have been leached off by the parasite.

I recommend giving the book a good oral anti-parasitic, which should be pressed between the pages of the index containing the letter "d" (for "digestive system") in the case of non-fiction, or anywhere in the chapter listings for fiction books.

Of course you can place it on any page you like if your book happens to be a reader's digest