32What happens to Joe & Tom after they smoke?

After smoking, Tom and Joe begin spitting a lot. They start to get pale. Joe drops his pipe, and then tells the other boys he thinks he's lost his knife in the forest. Tom offers to help look, and the boys tell Huck to stay put. Huck waits for an hour, and then goes to look for them. He finds them both asleep, far apart from each other, pale and obviously a little sick.