As Neville continues experimenting with vampires, he becomes more aware of the distinction between the two main kinds of vampires, living and dead. Humans who contract the vampire virus while they’re alive react to wooden stakes by spurting blood everywhere; those who contract the virus after they’re buried in the ground react by disintegrating into “salt and pepper.” The passage foreshadows the connection between Virginia and the vampires—as we’ll see later, that connection is important to Neville’s backstory.